//
//  SuperTuxKart - a fun racing game with go-kart
//  Copyright (C) 2004-2016 Steve Baker <sjbaker1@airmail.net>
//  Copyright (C) 2006-2016 SuperTuxKart-Team, Joerg Henrichs, Steve Baker
//
//  This program is free software; you can redistribute it and/or
//  modify it under the terms of the GNU General Public License
//  as published by the Free Software Foundation; either version 3
//  of the License, or (at your option) any later version.
//
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with this program; if not, write to the Free Software
//  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

#include "karts/kart.hpp"

#include "audio/sfx_manager.hpp"
#include "audio/sfx_base.hpp"
#include "challenges/challenge_status.hpp"
#include "challenges/unlock_manager.hpp"
#include "config/player_manager.hpp"
#include "config/user_config.hpp"
#include "font/bold_face.hpp"
#include "font/font_manager.hpp"
#include "graphics/camera/camera.hpp"
#include "graphics/central_settings.hpp"
#include "graphics/explosion.hpp"
#include "graphics/irr_driver.hpp"
#include "graphics/material.hpp"
#include "graphics/material_manager.hpp"
#include "graphics/particle_emitter.hpp"
#include "graphics/particle_kind_manager.hpp"
#include "graphics/shadow.hpp"
#include "graphics/skid_marks.hpp"
#include "graphics/slip_stream.hpp"
#include "graphics/stk_text_billboard.hpp"
#include "graphics/stars.hpp"
#include "guiengine/scalable_font.hpp"
#include "io/file_manager.hpp"
#include "items/attachment.hpp"
#include "items/item_manager.hpp"
#include "items/powerup.hpp"
#include "items/projectile_manager.hpp"
#include "karts/abstract_characteristic.hpp"
#include "karts/abstract_kart_animation.hpp"
#include "karts/cached_characteristic.hpp"
#include "karts/controller/local_player_controller.hpp"
#include "karts/controller/end_controller.hpp"
#include "karts/controller/spare_tire_ai.hpp"
#include "karts/explosion_animation.hpp"
#include "karts/kart_gfx.hpp"
#include "karts/kart_model.hpp"
#include "karts/kart_properties.hpp"
#include "karts/kart_properties_manager.hpp"
#include "karts/kart_rewinder.hpp"
#include "karts/max_speed.hpp"
#include "karts/rescue_animation.hpp"
#include "karts/skidding.hpp"
#include "main_loop.hpp"
#include "modes/capture_the_flag.hpp"
#include "modes/linear_world.hpp"
#include "modes/overworld.hpp"
#include "modes/soccer_world.hpp"
#include "network/compress_network_body.hpp"
#include "network/network_config.hpp"
#include "network/protocols/client_lobby.hpp"
#include "network/race_event_manager.hpp"
#include "network/rewind_info.hpp"
#include "network/rewind_manager.hpp"
#include "physics/btKart.hpp"
#include "physics/btKartRaycast.hpp"
#include "physics/physics.hpp"
#include "race/history.hpp"
#include "tracks/terrain_info.hpp"
#include "tracks/drive_graph.hpp"
#include "tracks/drive_node.hpp"
#include "tracks/track.hpp"
#include "tracks/track_manager.hpp"
#include "tracks/track_sector.hpp"
#include "utils/constants.hpp"
#include "utils/helpers.hpp"
#include "utils/log.hpp" //TODO: remove after debugging is done
#include "utils/profiler.hpp"
#include "utils/string_utils.hpp"
#include "utils/translation.hpp"
#include "utils/vs.hpp"

#include <ICameraSceneNode.h>
#include <IDummyTransformationSceneNode.h>
#include <ISceneManager.h>

#include <algorithm> // for min and max
#include <iostream>
#include <limits>
#include <cmath>


#if defined(WIN32) && !defined(__CYGWIN__)  && !defined(__MINGW32__)
   // Disable warning for using 'this' in base member initializer list
#  pragma warning(disable:4355)
#endif

/** The kart constructor.
 *  \param ident  The identifier for the kart model to use.
 *  \param position The position (or rank) for this kart (between 1 and
 *         number of karts). This is used to determine the start position.
 *  \param init_transform  The initial position and rotation for this kart.
 */
Kart::Kart (const std::string& ident, unsigned int world_kart_id,
            int position, const btTransform& init_transform,
            HandicapLevel handicap, std::shared_ptr<GE::GERenderInfo> ri)
     : AbstractKart(ident, world_kart_id, position, init_transform,
             handicap, ri)

#if defined(WIN32) && !defined(__CYGWIN__) && !defined(__MINGW32__)
#  pragma warning(1:4355)
#endif
{
    m_max_speed            = new MaxSpeed(this);
    m_terrain_info         = new TerrainInfo();
    m_powerup              = new Powerup(this);
    m_initial_position     = position;
    m_race_result          = false;
    m_wheel_box            = NULL;
#ifndef SERVER_ONLY
    m_collision_particles  = NULL;
#endif
    m_controller           = NULL;
    m_saved_controller     = NULL;
    m_consumption_per_tick = stk_config->ticks2Time(1) *
                             m_kart_properties->getNitroConsumption();
    m_fire_clicked         = 0;
    m_default_suspension_force = 0.0f;
    m_boosted_ai           = false;
    m_type                 = RaceManager::KT_AI;
    m_flying               = false;

    m_xyz_history_size     = stk_config->time2Ticks(XYZ_HISTORY_TIME);

    Vec3 initial_position = getXYZ();
    for (int i=0;i<m_xyz_history_size;i++)
    {
        m_previous_xyz.push_back(initial_position);
        m_previous_xyz_times.push_back(0.0f);
    }

    // Initialize custom sound vector (TODO: add back when properly done)
    // m_custom_sounds.resize(SFXManager::NUM_CUSTOMS);

    // Set position and heading:
    m_reset_transform         = init_transform;
    m_last_factor_engine_sound = 0.0f;

    m_kart_model->setKart(this);

    // Create SFXBase for each custom sound (TODO: add back when properly done)
    /*
    for (int n = 0; n < SFXManager::NUM_CUSTOMS; n++)
    {
        int id = m_kart_properties->getCustomSfxId((SFXManager::CustomSFX)n);

        // If id == -1 the custom sound was not defined in the .irrkart config file
        if (id != -1)
        {
            m_custom_sounds[n] = SFXManager::get()->newSFX(id);
        }
    }*/

    m_horn_sound = SFXManager::get()->getBuffer("horn");
    m_crash_sounds[0] = SFXManager::get()->getBuffer("crash");
    m_crash_sounds[1] = SFXManager::get()->getBuffer("crash2");
    m_crash_sounds[2] = SFXManager::get()->getBuffer("crash3");
    m_goo_sound = SFXManager::get()->getBuffer("goo");
    m_boing_sound = SFXManager::get()->getBuffer("boing");

    m_engine_sound = NULL;
    for (int i = 0; i < EMITTER_COUNT; i++)
        m_emitters[i] = SFXManager::get()->createSoundSource("crash");

    m_skid_sound = NULL;
    m_nitro_sound   = SFXManager::get()->createSoundSource( "nitro" );
    m_terrain_sound          = NULL;
    m_last_sound_material    = NULL;
    m_previous_terrain_sound = NULL;
}   // Kart

// -----------------------------------------------------------------------------
/** This is a second initialisation phase, necessary since in the constructor
 *  virtual functions are not called for any superclasses.
 *  \param type Type of the kart.
*/
void Kart::init(RaceManager::KartType type)
{
    m_type = type;

    loadData(type, UserConfigParams::m_animated_characters);
    // m_skid_sound is loaded in loadData
    initSound();
    reset();
}   // init

// ----------------------------------------------------------------------------
void Kart::initSound()
{
    // In multiplayer mode, sounds are NOT positional
    if (RaceManager::get()->getNumLocalPlayers() > 1)
    {
        float factor = 1.0f / RaceManager::get()->getNumberOfKarts();
        // players have louder sounds than AIs
        if (m_type == RaceManager::KT_PLAYER)
            factor = std::min(1.0f, RaceManager::get()->getNumLocalPlayers()/2.0f);

        for (int i = 0; i < EMITTER_COUNT; i++)
            m_emitters[i]->setVolume(factor);
        if (m_skid_sound)
            m_skid_sound->setVolume(factor);
        m_nitro_sound->setVolume(factor);
    }   // if getNumLocalPlayers > 1
}   // initSound

// ----------------------------------------------------------------------------
void Kart::changeKart(const std::string& new_ident,
                      HandicapLevel handicap,
                      std::shared_ptr<GE::GERenderInfo> ri,
                      const KartData& kart_data)
{
    AbstractKart::changeKart(new_ident, handicap, ri, kart_data);
    m_kart_model->setKart(this);

    scene::ISceneNode* old_node = m_node;
    loadData(m_type, UserConfigParams::m_animated_characters);
    initSound();
    m_wheel_box = NULL;

    if (LocalPlayerController* lpc =
        dynamic_cast<LocalPlayerController*>(getController()))
        lpc->initParticleEmitter();

    if (old_node)
        old_node->remove();

    // Reset 1 more time (add back the body)
    reset();

    for (int i = 0; i < m_vehicle->getNumWheels(); i++)
    {
        btWheelInfo &wi = m_vehicle->getWheelInfo(i);
        wi.m_raycastInfo.m_suspensionLength = m_default_suspension_force /
            m_vehicle->getNumWheels();
    }
    m_graphical_y_offset = -m_default_suspension_force /
        m_vehicle->getNumWheels() + m_kart_model->getLowestPoint();
    m_kart_model->setDefaultSuspension();
    startEngineSFX();
}   // changeKart

// ----------------------------------------------------------------------------
/** The destructor frees the memory of this kart, but note that the actual kart
 *  model is still stored in the kart_properties (m_kart_model variable), so
 *  it is not reloaded).
 */
Kart::~Kart()
{
    // Delete all custom sounds (TODO: add back when properly done)
    /*
    for (int n = 0; n < SFXManager::NUM_CUSTOMS; n++)
    {
        if (m_custom_sounds[n] != NULL)
            SFXManager::get()->deleteSFX(m_custom_sounds[n]);
    }*/

    if (m_engine_sound)
        m_engine_sound->deleteSFX();
    if (m_skid_sound)
        m_skid_sound->deleteSFX();

    for (int i = 0; i < EMITTER_COUNT; i++)
        m_emitters[i]->deleteSFX();

    m_nitro_sound ->deleteSFX();
    if(m_terrain_sound)          m_terrain_sound->deleteSFX();
    if(m_previous_terrain_sound) m_previous_terrain_sound->deleteSFX();
#ifndef SERVER_ONLY
    if(m_collision_particles)    delete m_collision_particles;
#endif

    if (m_wheel_box) m_wheel_box->remove();

    // Ghost karts don't have a body
    if(m_body)
    {
        Physics::get()->removeKart(this);
    }

    delete m_max_speed;
    delete m_terrain_info;
    delete m_powerup;

    if(m_controller)
        delete m_controller;
    if(m_saved_controller)
        delete m_saved_controller;
}   // ~Kart

//-----------------------------------------------------------------------------
/** Reset before a new race. It will remove all attachments, and
 *  puts the kart back at its original start position.
 */
void Kart::reset()
{
    if (m_flying && !isGhostKart())
    {
        m_flying = false;
        stopFlying();
    }

    m_network_finish_check_ticks = 0;
    m_network_confirmed_finish_ticks = 0;
    // Add karts back in case that they have been removed (i.e. in battle
    // mode) - but only if they actually have a body (e.g. ghost karts
    // don't have one).
    if(m_body)
    {
        Physics::get()->removeKart(this);
        Physics::get()->addKart(this);
    }

    m_min_nitro_ticks = 0;
    m_energy_to_min_ratio = 0;
    m_consumption_per_tick = stk_config->ticks2Time(1) *
                             m_kart_properties->getNitroConsumption();

    // Reset star effect in case that it is currently being shown.
    if (m_stars_effect)
        m_stars_effect->reset();
    m_max_speed->reset();
    m_powerup->reset();

    // Reset animations and wheels
    m_kart_model->reset();

    // If the controller was replaced (e.g. replaced by end controller),
    // restore the original controller.
    if(m_saved_controller)
    {
        delete m_controller;
        m_controller       = m_saved_controller;
        m_saved_controller = NULL;
    }
    m_kart_model->setAnimation(KartModel::AF_DEFAULT);
    m_attachment->reset();
    m_kart_gfx->reset();
    m_skidding->reset();

    m_weight = 0.0f;
    updateWeight();

#ifndef SERVER_ONLY
    if (m_collision_particles)
        m_collision_particles->setCreationRateAbsolute(0.0f);
#endif

    unsetSquash();

    m_last_used_powerup    = PowerupManager::POWERUP_NOTHING;
    m_race_position        = m_initial_position;
    m_finished_race        = false;
    m_eliminated           = false;
    m_finish_time          = 0.0f;
    m_bubblegum_ticks      = 0;
    m_bubblegum_torque_sign = true;
    m_invulnerable_ticks   = 0;
    m_min_nitro_ticks      = 0;
    m_energy_to_min_ratio  = 0;
    m_collected_energy     = 0;
    m_bounce_back_ticks    = 0;
    m_brake_ticks          = 0;
    m_ticks_last_crash     = 0;
    m_ticks_last_zipper    = 0;
    m_speed                = 0.0f;
    m_current_lean         = 0.0f;
    m_falling_time         = 0.0f;
    m_view_blocked_by_plunger = 0;
    m_has_caught_nolok_bubblegum = false;
    m_is_jumping           = false;
    m_flying               = false;
    m_startup_boost        = 0.0f;

    if (m_node)
        m_node->setScale(core::vector3df(1.0f, 1.0f, 1.0f));

    for (int i=0;i<m_xyz_history_size;i++)
    {
        m_previous_xyz[i] = getXYZ();
        m_previous_xyz_times[i] = 0.0f;
    }
    m_time_previous_counter = 0.0f;

    // In case that the kart was in the air, in which case its
    // linear damping is 0
    if(m_body)
        m_body->setDamping(m_kart_properties->getStabilityChassisLinearDamping(),
                           m_kart_properties->getStabilityChassisAngularDamping());

    if(m_terrain_sound)
    {
        m_terrain_sound->deleteSFX();
        m_terrain_sound = NULL;
    }
    if(m_previous_terrain_sound)
    {
        m_previous_terrain_sound->deleteSFX();
        m_previous_terrain_sound = NULL;
    }

    if(m_engine_sound)
        m_engine_sound->stop();

    m_controls.reset();
    m_slipstream->reset();
    
    if(m_vehicle)
    {
        for (unsigned int i = 0; i < 4; i++)
        {
            m_vehicle->getWheelInfo(i).m_steering = 0;
        }
            
        m_vehicle->reset();
    }

    setTrans(m_reset_transform);

    applyEngineForce (0.0f);

    AbstractKart::reset();
#ifndef SERVER_ONLY
    if (m_skidmarks)
    {
        m_skidmarks->reset();
    }
#endif

    Vec3 front(0, 0, getKartLength()*0.5f);
    m_xyz_front = getTrans()(front);

    // Base on update() below, require if starting point of kart is not near
    // 0, 0, 0 (like in battle arena)
    m_terrain_info->update(getTrans().getBasis(),
        getTrans().getOrigin() + getTrans().getBasis() * Vec3(0, 0.3f, 0));

    // Reset is also called when the kart is created, at which time
    // m_controller is not yet defined, so this has to be tested here.
    if(m_controller)
        m_controller->reset();

    // 3 strikes mode can hide the wheels
    scene::ISceneNode** wheels = getKartModel()->getWheelNodes();
    if(wheels[0]) wheels[0]->setVisible(true);
    if(wheels[1]) wheels[1]->setVisible(true);
    if(wheels[2]) wheels[2]->setVisible(true);
    if(wheels[3]) wheels[3]->setVisible(true);

}   // reset

// -----------------------------------------------------------------------------
void Kart::setXYZ(const Vec3& a)
{
    AbstractKart::setXYZ(a);
    Vec3 front(0, 0, getKartLength()*0.5f);
    m_xyz_front = getTrans()(front);
}    // setXYZ

// -----------------------------------------------------------------------------
void Kart::increaseMaxSpeed(unsigned int category, float add_speed,
                            float engine_force, int duration,
                            int fade_out_time)
{
    m_max_speed->increaseMaxSpeed(category, add_speed, engine_force,
                                  duration, fade_out_time);
}   // increaseMaxSpeed

// -----------------------------------------------------------------------------
void Kart::instantSpeedIncrease(unsigned int category, float add_max_speed,
                               float speed_boost, float engine_force,
                               int duration, int fade_out_time)
{
    m_max_speed->instantSpeedIncrease(category, add_max_speed, speed_boost,
                                      engine_force, duration, fade_out_time);
}   // instantSpeedIncrease

// -----------------------------------------------------------------------------
void Kart::setSlowdown(unsigned int category, float max_speed_fraction,
                       int fade_in_time)
{
    m_max_speed->setSlowdown(category, max_speed_fraction,  fade_in_time);
}   // setSlowdown

// -----------------------------------------------------------------------------
float Kart::getCurrentMaxSpeed() const
{
    return m_max_speed->getCurrentMaxSpeed();
}   // getCurrentMaxSpeed
// -----------------------------------------------------------------------------
int Kart::getSpeedIncreaseTicksLeft(unsigned int category) const
{
    return m_max_speed->getSpeedIncreaseTicksLeft(category);
}   // getSpeedIncreaseTimeLeft

// -----------------------------------------------------------------------------
void Kart::setBoostAI(bool boosted)
{
    m_boosted_ai = boosted;
}   // setBoostAI
// -----------------------------------------------------------------------------
bool Kart::getBoostAI() const
{
    return m_boosted_ai;
}   // getBoostAI

// -----------------------------------------------------------------------------
/** Returns the current material the kart is on. */
const Material *Kart::getMaterial() const
{
    return m_terrain_info->getMaterial();
}   // getMaterial

// -----------------------------------------------------------------------------
/** Returns the previous material the kart was one (which might be
 *  the same as getMaterial() ). */
const Material *Kart::getLastMaterial() const
{
    return m_terrain_info->getLastMaterial();
}   // getLastMaterial
// -----------------------------------------------------------------------------
/** Returns the pitch of the terrain depending on the heading. */
float Kart::getTerrainPitch(float heading) const
{
    return m_terrain_info->getTerrainPitch(heading);
}   // getTerrainPitch

// -----------------------------------------------------------------------------
/** Returns the height of the terrain. we're currently above */
float Kart::getHoT() const
{
    return m_terrain_info->getHoT();
}   // getHoT

// ----------------------------------------------------------------------------
/** Sets the powerup this kart has collected.
 *  \param t Type of the powerup.
 *  \param n Number of powerups collected.
 */
void Kart::setPowerup(PowerupManager::PowerupType t, int n)
{
    m_powerup->set(t, n);
}   // setPowerup

// ----------------------------------------------------------------------------
/** Sets the powerup this kart has last used. Number is always 1.
 *  \param t Type of the powerup.
 */
void Kart::setLastUsedPowerup(PowerupManager::PowerupType t)
{
    m_last_used_powerup = t;
}   // setLastUsedPowerup

// -----------------------------------------------------------------------------
int Kart::getNumPowerup() const
{
    return m_powerup->getNum();
}   // getNumPowerup

// -----------------------------------------------------------------------------
/** Saves the old controller in m_saved_controller and stores a new
 *  controller. The save controller is needed in case of a reset.
 *  \param controller The new controller to use (atm it's always an
 *         end controller).
 */
void Kart::setController(Controller *controller)
{
    assert(m_saved_controller==NULL);
    m_saved_controller = m_controller;
    m_controller       = controller;
}   // setController

// -----------------------------------------------------------------------------
/** Sets the position in race this kart has .
 *  The position in this race for this kart (1<=p<=n)
 */
void Kart::setPosition(int p)
{
    m_controller->setPosition(p);
    m_race_position = p;
}   // setPosition

// -----------------------------------------------------------------------------
/** Sets that the view is blocked by a plunger. The duration depends on
 *  the difficulty, see KartPorperties getPlungerInFaceTime.
 */
void Kart::blockViewWithPlunger()
{
    // Avoid that a plunger extends the plunger time
    if(m_view_blocked_by_plunger<=0 && !isShielded())
    {
        m_view_blocked_by_plunger = (int16_t)
            stk_config->time2Ticks(m_kart_properties->getPlungerInFaceTime());
    }
    if(isShielded())
    {
        decreaseShieldTime();
    }
}   // blockViewWithPlunger

// -----------------------------------------------------------------------------
/** Returns a transform that will align an object with the kart: the heading
 *  and the pitch will be set appropriately. A custom pitch value can be
 *  specified in order to overwrite the terrain pitch (which would be used
 *  otherwise).
 *  \param custom_pitch Pitch value to overwrite the terrain pitch. A value of
 *         -1 indicates that the custom_pitch value should not be used, instead
 *         the actual pitch of the terrain is to be used.
 */
btTransform Kart::getAlignedTransform(const float custom_pitch)
{
    btTransform trans = getTrans();
    /*
    float pitch = (custom_pitch == -1 ? getTerrainPitch(getHeading())
                                      : custom_pitch);

    btMatrix3x3 m;
    m.setEulerZYX(pitch, getHeading()+m_skidding->getVisualSkidRotation(),
                  0.0f);
    trans.setBasis(m);
    */
    btTransform trans2;
    trans2.setIdentity();
    trans2.setRotation(btQuaternion(m_skidding->getVisualSkidRotation(), 0, 0));
    trans *= trans2;
    
    return trans;
}   // getAlignedTransform

// ----------------------------------------------------------------------------
float Kart::getTimeFullSteer(float steer) const
{
    return m_kart_properties->getTurnTimeFullSteer().get(steer);
}   // getTimeFullSteer

// ----------------------------------------------------------------------------
/** Creates the physical representation of this kart. Atm it uses the actual
 *  extention of the kart model to determine the size of the collision body.
 */
void Kart::createPhysics()
{
    // First: Create the chassis of the kart
    // -------------------------------------
    const float kart_length = getKartLength();
    const float kart_width  = getKartWidth();
    float       kart_height = getKartHeight();

    // improve physics for tall karts
    if (kart_height > kart_length*0.6f)
    {
        kart_height = kart_length*0.6f;
    }

    const Vec3 &bevel = m_kart_properties->getBevelFactor();
    Vec3 wheel_pos[4];

    Vec3 orig_factor(1, 1, 1 - bevel.getZ());
    Vec3 bevel_factor(1.0f - bevel.getX(), 1.0f - bevel.getY(), 1.0f);
    btConvexHullShape *hull = new btConvexHullShape();
    for (int y = -1; y <= 1; y += 2)
    {
        for (int z = -1; z <= 1; z += 2)
        {
            for (int x = -1; x <= 1; x += 2)
            {
                Vec3 p(x*kart_width  *0.5f,
                       y*kart_height *0.5f,
                       z*kart_length *0.5f);

                hull->addPoint(p*orig_factor);
                // Only add bevelled point if bevel is defined (i.e.!=0)
                if(bevel.length2()>0)
                    hull->addPoint(p*bevel_factor);
                if (y == -1)
                {
                    int index = (x + 1) / 2 + 1 - z;  // get index of wheel
                    float f = m_kart_properties->getPhysicalWheelPosition();
                    // f < 0 indicates to use the old physics position, i.e.
                    // to place the wheels outside of the chassis
                    if(f<0)
                    {
                        // All wheel positions are relative to the center of
                        // the collision shape.
                        wheel_pos[index].setX(x*0.5f*kart_width);
                        wheel_pos[index].setZ((0.5f*kart_length-0.25f)* z);
                    }
                    else
                    {
                        // Store the x/z position for the wheels as a weighted average
                        // of the two bevelled points (y is set below).
                        wheel_pos[index] = p*(orig_factor*(1.0f - f) + bevel_factor*f);
                    }
                    // The y position of the wheels (i.e. the points where
                    // the suspension is attached to) is just at the
                    // bottom of the kart (independent of collision shape). 
                    // That is half the kart height down.
                    wheel_pos[index].setY(-0.5f*kart_height);
                }  // if y==-1
            }   // for x
        }   // for z
    }   // for y

    // This especially enables proper drawing of the point cloud
    hull->initializePolyhedralFeatures();

    btTransform shiftCenterOfGravity;
    shiftCenterOfGravity.setIdentity();
    // Shift center of gravity downwards, so that the kart
    // won't topple over too easy.
    shiftCenterOfGravity.setOrigin(m_kart_properties->getGravityCenterShift());
    m_kart_chassis.reset(new btCompoundShape());
    m_kart_chassis->addChildShape(shiftCenterOfGravity, hull);

    // Set mass and inertia
    // --------------------
    float mass = m_kart_properties->getMass();

    // Position the chassis
    // --------------------
    btTransform trans;
    trans.setIdentity();
    createBody(mass, trans, m_kart_chassis.get(),
               m_kart_properties->getRestitution(0.0f));
    std::vector<float> ang_fact = m_kart_properties->getStabilityAngularFactor();
    // The angular factor (with X and Z values <1) helps to keep the kart
    // upright, especially in case of a collision.
    m_body->setAngularFactor(Vec3(ang_fact[0], ang_fact[1], ang_fact[2]));
    m_body->setFriction(m_kart_properties->getFrictionKartFriction());
    m_user_pointer.set(this);
    m_body->setDamping(m_kart_properties->getStabilityChassisLinearDamping(),
                       m_kart_properties->getStabilityChassisAngularDamping() );

    // Reset velocities
    // ----------------
    m_body->setLinearVelocity (btVector3(0.0f,0.0f,0.0f));
    m_body->setAngularVelocity(btVector3(0.0f,0.0f,0.0f));

    // Create the actual vehicle
    // -------------------------
    m_vehicle_raycaster.reset(
        new btKartRaycaster(Physics::get()->getPhysicsWorld(),
                            stk_config->m_smooth_normals &&
                            Track::getCurrentTrack()->smoothNormals()));
    m_vehicle.reset(new btKart(m_body.get(), m_vehicle_raycaster.get(), this));

    // never deactivate the vehicle
    m_body->setActivationState(DISABLE_DEACTIVATION);

    // Add wheels
    // ----------
    float suspension_rest = m_kart_properties->getSuspensionRest();

    btVector3 wheel_direction(0.0f, -1.0f, 0.0f);
    btVector3 wheel_axle(-1.0f, 0.0f, 0.0f);

    btKart::btVehicleTuning tuning;
    tuning.m_maxSuspensionTravel =
        m_kart_properties->getSuspensionTravel();
    tuning.m_maxSuspensionForce    =
        m_kart_properties->getSuspensionMaxForce();

    const Vec3 &cs = m_kart_properties->getGravityCenterShift();
    for(unsigned int i=0; i<4; i++)
    {
        bool is_front_wheel = i<2;
        btWheelInfo& wheel = m_vehicle->addWheel(
                            wheel_pos[i]+cs,
                            wheel_direction, wheel_axle, suspension_rest,
                            m_kart_model->getWheelGraphicsRadius(i),
                            tuning, is_front_wheel);
        wheel.m_suspensionStiffness      = m_kart_properties->getSuspensionStiffness();
        wheel.m_wheelsDampingRelaxation  = m_kart_properties->getWheelsDampingRelaxation();
        wheel.m_wheelsDampingCompression = m_kart_properties->getWheelsDampingCompression();
        wheel.m_frictionSlip             = m_kart_properties->getFrictionSlip();
        wheel.m_rollInfluence            = m_kart_properties->getStabilityRollInfluence();
    }
    // Body to be added in reset() which allows complete reset kart when
    // restarting the race

}   // createPhysics

// ----------------------------------------------------------------------------

void Kart::flyUp()
{
    m_flying = true;
    Moveable::flyUp();
}   // flyUp

// ----------------------------------------------------------------------------
void Kart::flyDown()
{
    if (isNearGround())
    {
        stopFlying();
        m_flying = false;
    }
    else
    {
        Moveable::flyDown();
    }
}   // flyDown

// ----------------------------------------------------------------------------
/** Starts the engine sound effect. Called once the track intro phase is over.
 */
void Kart::startEngineSFX()
{
    if(!m_engine_sound)
        return;

    // In multiplayer mode, sounds are NOT positional (because we have
    // multiple listeners) so the engine sounds of all AIs is constantly
    // heard. So reduce volume of all sounds.
    if (RaceManager::get()->getNumLocalPlayers() > 1)
    {
        const int np = RaceManager::get()->getNumLocalPlayers();
        const int nai = RaceManager::get()->getNumberOfKarts() - np;

        // player karts twice as loud as AIs toghether
        const float players_volume = (np * 2.0f) / (np*2.0f + np);

        if (m_controller->isLocalPlayerController())
            m_engine_sound->setVolume( players_volume / np );
        else
            m_engine_sound->setVolume( (1.0f - players_volume) / nai );
    }

    m_engine_sound->setSpeed(0.6f);
    m_engine_sound->setLoop(true);
    m_engine_sound->play();
}   // startEngineSFX

//-----------------------------------------------------------------------------
/** Returns true if the kart is 'resting', i.e. (nearly) not moving.
 */
bool Kart::isInRest() const
{
    return fabsf(m_body->getLinearVelocity ().y())<0.2f;
}  // isInRest

//-----------------------------------------------------------------------------
/** Multiplies the velocity of the kart by a factor f (both linear
 *  and angular). This is used by anvils, which suddenly slow down the kart
 *  when they are attached.
 */
void Kart::adjustSpeed(float f)
{
    m_body->setLinearVelocity(m_body->getLinearVelocity()*f);
    m_body->setAngularVelocity(m_body->getAngularVelocity()*f);
}   // adjustSpeed

//-----------------------------------------------------------------------------
/** This method is to be called every time the mass of the kart is updated,
 *  which includes attaching an anvil to the kart (and detaching).
 */
void Kart::updateWeight()
{
    if (!m_body)
        return;
    float mass = m_kart_properties->getMass() + m_attachment->weightAdjust();
    if (m_weight != mass)
    {
        m_weight = mass;
        btVector3 inertia;
        m_kart_chassis->calculateLocalInertia(mass, inertia);
        m_body->setMassProps(mass, inertia);
    }
}   // updateWeight

// ------------------------------------------------------------------------
/** Returns the (maximum) speed for a given turn radius.
 *  \param radius The radius for which the speed needs to be computed. */
float Kart::getSpeedForTurnRadius(float radius) const
{
    InterpolationArray turn_angle_at_speed = m_kart_properties->getTurnRadius();
    // Convert the turn radius into turn angle
    for(int i = 0; i < (int)turn_angle_at_speed.size(); i++)
        turn_angle_at_speed.setY(i, sinf( 1.0f / turn_angle_at_speed.getY(i)));

    float angle = sinf(1.0f / radius);
    return turn_angle_at_speed.getReverse(angle);
}   // getSpeedForTurnRadius

// ------------------------------------------------------------------------
/** Returns the maximum steering angle (depending on speed).
    This is proportional to kart length because physics reverse this effect,
    the results of this function should not be used to determine the
    real raw steer angle. */
float Kart::getMaxSteerAngle(float speed) const
{
    InterpolationArray turn_angle_at_speed = m_kart_properties->getTurnRadius();
    // Convert the turn radius into turn angle
    // We multiply by wheel base to keep turn radius identical
    // across karts of different lengths sharing the same
    // turn radius properties
    for(int i = 0; i < (int)turn_angle_at_speed.size(); i++)
        turn_angle_at_speed.setY(i, sinf( 1.0f / turn_angle_at_speed.getY(i))
                                    * m_kart_properties->getWheelBase());

    return turn_angle_at_speed.get(speed);
}   // getMaxSteerAngle

//-----------------------------------------------------------------------------
/** Sets that this kart has finished the race and finishing time. It also
 *  notifies the race_manager about the race completion for this kart.
 *  \param time The finishing time for this kart. It can either be the
 *         actual time when the kart finished (in which case time() =
 *         world->getTime()), or the estimated time in case that all
 *         player kart have finished the race and all AI karts get
 *         an estimated finish time set.
 *  \param from_server In a network game, only the server can notify
 *         about a kart finishing a race. This parameter is to distinguish
 *         between a local detection (which is ignored on clients in a
 *         network game), and a server notification.
 */
void Kart::finishedRace(float time, bool from_server)
{
    // m_finished_race can be true if e.g. an AI kart was set to finish
    // because the race was over (i.e. estimating the finish time). If
    // this kart then crosses the finish line (with the end controller)
    // it would trigger a race end again.
    if (m_finished_race) return;

    const bool is_linear_race =
        RaceManager::get()->getMinorMode() == RaceManager::MINOR_MODE_NORMAL_RACE ||
        RaceManager::get()->getMinorMode() == RaceManager::MINOR_MODE_TIME_TRIAL  ||
        RaceManager::get()->getMinorMode() == RaceManager::MINOR_MODE_FOLLOW_LEADER;
    if (NetworkConfig::get()->isNetworking() && !from_server)
    {
        if (NetworkConfig::get()->isServer())
        {
            RaceEventManager::get()->kartFinishedRace(this, time);
        }   // isServer

        // Ignore local detection of a kart finishing a race in a 
        // network game.
        else if (NetworkConfig::get()->isClient())
        {
            if (is_linear_race && m_saved_controller == NULL &&
                !RewindManager::get()->isRewinding())
            {
                m_network_finish_check_ticks =
                    World::getWorld()->getTicksSinceStart() +
                    stk_config->time2Ticks(1.0f);
                EndController* ec = new EndController(this, m_controller);
                Controller* old_controller = m_controller;
                setController(ec);
                // Seamless endcontroller replay
                RewindManager::get()->addRewindInfoEventFunction(new
                RewindInfoEventFunction(
                    World::getWorld()->getTicksSinceStart(),
                    /*undo_function*/[old_controller, this]()
                    {
                        if (m_network_finish_check_ticks == -1)
                            return;

                        m_controller = old_controller;
                    },
                    /*replay_function*/[ec, old_controller, this]()
                    {
                        if (m_network_finish_check_ticks == -1)
                            return;

                        m_saved_controller = old_controller;
                        ec->reset();
                        m_controller = ec;
                    }));
            }
            return;
        }
    }   // !from_server

    if (NetworkConfig::get()->isClient())
    {
        m_network_confirmed_finish_ticks =
            World::getWorld()->getTicksSinceStart();
    }

    m_finished_race = true;

    m_finish_time   = time;

    m_controller->finishedRace(time);
    m_kart_model->finishedRace();
    RaceManager::get()->kartFinishedRace(this, time);

    // If this is spare tire kart, end now
    if (dynamic_cast<SpareTireAI*>(m_controller) != NULL) return;

    if (is_linear_race && m_controller->isPlayerController() && !m_eliminated)
    {
        RaceGUIBase* m = World::getWorld()->getRaceGUI();
        if (m)
        {
            bool won_the_race = false, too_slow = false, one_kart = false;
            unsigned int win_position = 1;

            if (RaceManager::get()->getMinorMode() == RaceManager::MINOR_MODE_FOLLOW_LEADER)
                win_position = 2;

            // There is no win if there is no possibility of losing
            if (RaceManager::get()->getNumberOfKarts() == 1)
                one_kart = true;

            if ((getPosition() == (int)win_position &&
                World::getWorld()->getNumKarts() > win_position))
                won_the_race = true;

            if (RaceManager::get()->hasTimeTarget() && m_finish_time > RaceManager::get()->getTimeTarget())
                too_slow = true;

            m->addMessage((too_slow     ? _("You were too slow!")     :
                           one_kart     ? _("You finished the race!") :
                           won_the_race ? _("You won the race!")      :
                                          _("You finished the race in rank %d!", getPosition())),
            this, 2.0f, video::SColor(255, 255, 255, 255), true, true, true);
        }
    }

    if (RaceManager::get()->isLinearRaceMode() || RaceManager::get()->isBattleMode() ||
        RaceManager::get()->isSoccerMode()     || RaceManager::get()->isEggHuntMode() ||
        RaceManager::get()->isLapTrialMode())
    {
        // Save for music handling in race result gui
        setRaceResult();
        if (!isGhostKart())
        {
            if (m_saved_controller == NULL)
            {
                setController(new EndController(this, m_controller));
            }
            else
                m_saved_controller->finishedRace(time);
        }
        // Skip animation if this kart is eliminated
        if (m_eliminated || isGhostKart()) return;

        m_kart_model->setAnimation(m_race_result ?
            KartModel::AF_WIN_START : KartModel::AF_LOSE_START);
    }
}   // finishedRace

//-----------------------------------------------------------------------------
void Kart::setRaceResult()
{
    if (RaceManager::get()->getMinorMode() == RaceManager::MINOR_MODE_NORMAL_RACE ||
        RaceManager::get()->getMinorMode() == RaceManager::MINOR_MODE_TIME_TRIAL  ||
        RaceManager::get()->isLapTrialMode())
    {
        if (m_controller->isLocalPlayerController()) // if player is on this computer
        {
            PlayerProfile *player = PlayerManager::getCurrentPlayer();
            const ChallengeStatus *challenge = player->getCurrentChallengeStatus();
            // In case of a GP challenge don't make the end animation depend
            // on if the challenge is fulfilled
            if (challenge && !challenge->getData()->isGrandPrix())
            {
                if (challenge->getData()->isChallengeFulfilled())
                    m_race_result = true;
                else
                    m_race_result = false;
            }
            else if (this->getPosition() <= 0.5f *
                World::getWorld()->getCurrentNumKarts() ||
                this->getPosition() == 1)
                m_race_result = true;
            else
                m_race_result = false;
        }
        else
        {
            if (this->getPosition() <= 0.5f *
                World::getWorld()->getCurrentNumKarts() ||
                this->getPosition() == 1)
                m_race_result = true;
            else
                m_race_result = false;
        }
    }
    else if (RaceManager::get()->getMinorMode() == RaceManager::MINOR_MODE_FOLLOW_LEADER ||
             RaceManager::get()->getMinorMode() == RaceManager::MINOR_MODE_3_STRIKES)
    {
        // the kart wins if it isn't eliminated
        m_race_result = !this->isEliminated();
    }
    else if (RaceManager::get()->getMinorMode() == RaceManager::MINOR_MODE_FREE_FOR_ALL)
    {
        FreeForAll* ffa = dynamic_cast<FreeForAll*>(World::getWorld());
        m_race_result = ffa->getKartFFAResult(getWorldKartId());
    }
    else if (RaceManager::get()->getMinorMode() == RaceManager::MINOR_MODE_CAPTURE_THE_FLAG)
    {
        CaptureTheFlag* ctf = dynamic_cast<CaptureTheFlag*>(World::getWorld());
        m_race_result = ctf->getKartCTFResult(getWorldKartId());
    }
    else if (RaceManager::get()->getMinorMode() == RaceManager::MINOR_MODE_SOCCER)
    {
        SoccerWorld* sw = dynamic_cast<SoccerWorld*>(World::getWorld());
        m_race_result = sw->getKartSoccerResult(this->getWorldKartId());
    }
    else if (RaceManager::get()->getMinorMode() == RaceManager::MINOR_MODE_EASTER_EGG)
    {
        // Easter egg mode only has one player, so always win
        m_race_result = true;
    }
    else
        Log::warn("Kart", "Unknown game mode given.");

}   // setRaceResult

//-----------------------------------------------------------------------------
/** Called when an item is collected. It will either adjust the collected
 *  energy, or update the attachment or powerup for this kart.
 *  \param item_state The item that was hit.
 */
void Kart::collectedItem(ItemState *item_state)
{
    float old_energy          = m_collected_energy;
    const Item::ItemType type = item_state->getType();

    switch (type)
    {
    case Item::ITEM_BANANA:
        m_attachment->hitBanana(item_state);
        break;
    case Item::ITEM_NITRO_SMALL:
        m_collected_energy += m_kart_properties->getNitroSmallContainer();
        break;
    case Item::ITEM_NITRO_BIG:
        m_collected_energy += m_kart_properties->getNitroBigContainer();
        break;
    case Item::ITEM_BONUS_BOX  :
        {
            m_powerup->hitBonusBox(*item_state);
            break;
        }
    case Item::ITEM_BUBBLEGUM:
        m_has_caught_nolok_bubblegum = 
            (item_state->getPreviousOwner()&&
             item_state->getPreviousOwner()->getIdent() == "nolok");

        // slow down
        m_bubblegum_ticks = (int16_t)stk_config->time2Ticks(
            m_kart_properties->getBubblegumDuration());
        m_bubblegum_torque_sign =
            ((World::getWorld()->getTicksSinceStart() / 10) % 2 == 0) ?
            true : false;
        m_max_speed->setSlowdown(MaxSpeed::MS_DECREASE_BUBBLE,
            m_kart_properties->getBubblegumSpeedFraction() ,
            stk_config->time2Ticks(m_kart_properties->getBubblegumFadeInTime()),
            m_bubblegum_ticks);
        if (!RewindManager::get()->isRewinding())
            getNextEmitter()->play(getSmoothedXYZ(), m_goo_sound);

        // Play appropriate custom character sound
        playCustomSFX(SFXManager::CUSTOM_GOO);
        break;
    default        : break;
    }   // switch TYPE

    if ( m_collected_energy > m_kart_properties->getNitroMax())
        m_collected_energy = m_kart_properties->getNitroMax();
    m_controller->collectedItem(*item_state, old_energy);

}   // collectedItem

//-----------------------------------------------------------------------------
/** Called the first time a kart accelerates after 'ready'. It searches
 *  through the startup times to find the appropriate slot, and returns the
 *  speed-boost from the corresponding entry.
 *  If the kart started too slow (i.e. slower than the longest time in the
 *  startup times list), it returns 0.
 */
float Kart::getStartupBoostFromStartTicks(int ticks) const
{
    int ticks_since_ready = ticks - stk_config->time2Ticks(1.0f);
    if (ticks_since_ready < 0)
        return 0.0f;
    float t = stk_config->ticks2Time(ticks_since_ready);
    std::vector<float> startup_times = m_kart_properties->getStartupTime();
    for (unsigned int i = 0; i < startup_times.size(); i++)
    {
        if (t <= startup_times[i])
            return m_kart_properties->getStartupBoost()[i];
    }
    return 0.0f;
}   // getStartupBoostFromStartTicks

//-----------------------------------------------------------------------------
/** Simulates gears by adjusting the force of the engine. It also takes the
 *  effect of the zipper into account.
 */
float Kart::getActualWheelForce()
{
    float add_force = m_max_speed->getCurrentAdditionalEngineForce();
    assert(!std::isnan(add_force));
    const std::vector<float>& gear_ratio=m_kart_properties->getGearSwitchRatio();
    for(unsigned int i=0; i<gear_ratio.size(); i++)
    {
        if(m_speed <= m_kart_properties->getEngineMaxSpeed() * gear_ratio[i])
        {
            assert(!std::isnan(m_kart_properties->getEnginePower()));
            assert(!std::isnan(m_kart_properties->getGearPowerIncrease()[i]));
            return m_kart_properties->getEnginePower()
                 * m_kart_properties->getGearPowerIncrease()[i]
                 + add_force;
        }
    }
    assert(!std::isnan(m_kart_properties->getEnginePower()));
    return m_kart_properties->getEnginePower() + add_force * 2;

}   // getActualWheelForce

//-----------------------------------------------------------------------------
/** The kart is on ground if all 4 wheels touch the ground, and if no special
 *  animation (rescue, explosion etc.) is happening).
 */
bool Kart::isOnGround() const
{
    return ((int)m_vehicle->getNumWheelsOnGround() == m_vehicle->getNumWheels()
          && !getKartAnimation());
}   // isOnGround

//-----------------------------------------------------------------------------
/** The kart is near the ground, but not necessarily on it (small jumps). This
 *  is used to determine when to stop flying.
*/
bool Kart::isNearGround() const
{
    if((m_terrain_info->getHitPoint() - getXYZ()).length() ==Track::NOHIT)
        return false;
    else
        return ((getXYZ().getY() - m_terrain_info->getHoT())
                 < stk_config->m_near_ground);
}   // isNearGround

// ------------------------------------------------------------------------
/** Enables a kart shield protection for a certain amount of time.
 */
void Kart::setShieldTime(float t)
{
    if(isShielded())
    {
        getAttachment()->setTicksLeft(stk_config->time2Ticks(t));
    }
}   // setShieldTime

// ------------------------------------------------------------------------
/**
 * Returns true if the kart is protected by a shield.
 */
bool Kart::isShielded() const
{
    if(getAttachment() != NULL)
    {
        Attachment::AttachmentType type = getAttachment()->getType();
        return type == Attachment::ATTACH_BUBBLEGUM_SHIELD ||
               type == Attachment::ATTACH_NOLOK_BUBBLEGUM_SHIELD;
    }
    else
    {
        return false;
    }
}   // isShielded

// ------------------------------------------------------------------------
/**
 *Returns the remaining time the kart is protected by a shield.
 */
float Kart::getShieldTime() const
{
    if (isShielded())
        return stk_config->ticks2Time(getAttachment()->getTicksLeft());
    else
        return 0.0f;
}   // getShieldTime

// ------------------------------------------------------------------------
/**
 * Decreases the kart's shield time.
 * \param t The time subtracted from the shield timer. If t == 0.0f, the
             default amout of time is subtracted.
 */
void Kart::decreaseShieldTime()
{
    if (isShielded())
    {
        getAttachment()->setTicksLeft(0);
    }
}   // decreaseShieldTime

//-----------------------------------------------------------------------------
/** Shows the star effect for a certain time.
 *  \param t Time to show the star effect for.
 */
void Kart::showStarEffect(float t)
{
    if (m_stars_effect)
        m_stars_effect->showFor(t);
}   // showStarEffect

//-----------------------------------------------------------------------------
void Kart::eliminate()
{
    if (!getKartAnimation())
    {
        Physics::get()->removeKart(this);
    }
    if (m_stars_effect)
    {
        m_stars_effect->reset();
        m_stars_effect->update(1);
    }

    if (m_attachment)
        m_attachment->clear();

    if (m_slipstream)
        m_slipstream->reset();

    m_kart_gfx->setCreationRateAbsolute(KartGFX::KGFX_TERRAIN, 0);
    m_kart_gfx->setGFXInvisible();

    if (m_engine_sound)
        m_engine_sound->stop();

    m_eliminated = true;

#ifndef SERVER_ONLY
    if (m_shadow)
        m_shadow->update(false);
#endif
    if (m_node)
        m_node->setVisible(false);
}   // eliminate

//-----------------------------------------------------------------------------
/** Updates the kart in each time step. It updates the physics setting,
 *  particle effects, camera position, etc.
 *  \param dt Time step size.
 */
void Kart::update(int ticks)
{
    if (m_network_finish_check_ticks > 0 &&
        World::getWorld()->getTicksSinceStart() >
        m_network_finish_check_ticks &&
        !m_finished_race && m_saved_controller != NULL)
    {
        Log::warn("Kart", "Missing finish race from server.");
        m_network_finish_check_ticks = -1;
        delete m_controller;
        m_controller = m_saved_controller;
        m_saved_controller = NULL;
    }

    m_powerup->update(ticks);

    // Reset any instant speed increase in the bullet kart
    m_vehicle->resetMaxSpeed();

    if (m_bubblegum_ticks > 0)
        m_bubblegum_ticks -= ticks;

    // This is to avoid a rescue immediately after an explosion
    const bool has_animation_before = m_kart_animation != NULL;
    // A kart animation can change the xyz position. This needs to be done
    // before updating the graphical position (which is done in
    // Moveable::update() ), otherwise 'stuttering' can happen (caused by
    // graphical and physical position not being the same).
    if (has_animation_before)
    {
        m_kart_animation->update(ticks);
    }
    else if (NetworkConfig::get()->roundValuesNow())
        CompressNetworkBody::compress(m_body.get(), m_motion_state.get());

    float dt = stk_config->ticks2Time(ticks);
    if (!RewindManager::get()->isRewinding())
    {
        m_time_previous_counter += dt;
        while (m_time_previous_counter > stk_config->ticks2Time(1))
        {
            m_previous_xyz[0] = getXYZ();
            m_previous_xyz_times[0] = World::getWorld()->getTime();
            for (int i=m_xyz_history_size-1;i>0;i--)
            {
                m_previous_xyz[i] = m_previous_xyz[i-1];
                m_previous_xyz_times[i] = m_previous_xyz_times[i-1];
            }
            m_time_previous_counter -= stk_config->ticks2Time(1);
        }
    }

    // Update the position and other data taken from the physics (or
    // an animation which calls setXYZ(), which also updates the kart
    // physical position).
    Moveable::update(ticks);

    Vec3 front(0, 0, getKartLength()*0.5f);
    m_xyz_front = getTrans()(front);

    // Hover the kart above reset position before entering the game
    // Add invulnerability depends on kart
    if (m_live_join_util != 0 &&
        ((m_live_join_util > World::getWorld()->getTicksSinceStart() &&
        World::getWorld()->isActiveRacePhase()) ||
        World::getWorld()->isLiveJoinWorld()))
    {
        btRigidBody *body = getBody();
        body->clearForces();
        body->setLinearVelocity(Vec3(0.0f));
        body->setAngularVelocity(Vec3(0.0f));
        btTransform hovering = m_starting_transform;
        hovering.setOrigin(hovering.getOrigin() +
            m_starting_transform.getBasis().getColumn(1) * 3.0f);
        body->proceedToTransform(hovering);
        setTrans(hovering);
        float time = getKartProperties()->getExplosionInvulnerabilityTime();
        m_invulnerable_ticks = stk_config->time2Ticks(time);
    }

    // Update the locally maintained speed of the kart (m_speed), which 
    // is used furthermore for engine power, camera distance etc
    updateSpeed();
    // Make the restitution depend on speed: this avoids collision issues,
    // otherwise a collision with high speed can see a kart being push
    // high up in the air (and out of control). So for higher speed we
    // reduce the restitution, meaning the karts will get less of a push
    // based on the collision speed.
    m_body->setRestitution(m_kart_properties->getRestitution(fabsf(m_speed)));

    m_controller->update(ticks);

#ifndef SERVER_ONLY
#undef DEBUG_CAMERA_SHAKE
#ifdef DEBUG_CAMERA_SHAKE
    Log::verbose("camera", "%s t %f %d xyz %f %f %f v %f %f %f d3 %f d2 %f",
        getIdent().c_str(),
        World::getWorld()->getTime(), ticks,
        getXYZ().getX(), getXYZ().getY(), getXYZ().getZ(),
        getVelocity().getX(), getVelocity().getY(), getVelocity().getZ(),
        (Camera::getCamera(0)->getXYZ()-getXYZ()).length(),
        (Camera::getCamera(0)->getXYZ()-getXYZ()).length_2d()
        );
#endif
#endif

#undef DEBUG_TO_COMPARE_KART_PHYSICS
#ifdef DEBUG_TO_COMPARE_KART_PHYSICS
    // This information is useful when comparing kart physics, e.g. to
    // see top speed, acceleration (i.e. time to top speed) etc.
    Log::verbose("physics", "     %s t %f %d xyz(9-11) %f %f %f v(13-15) %f %f %f steerf(17) %f maxangle(19) %f speed(21) %f steering(23-24) %f %f clock %lf",
        getIdent().c_str(),
        World::getWorld()->getTime(), ticks,
        getXYZ().getX(), getXYZ().getY(), getXYZ().getZ(),
        getVelocity().getX(), getVelocity().getY(), getVelocity().getZ(),  //13,14,15
        m_skidding->getSteeringFraction(), //19
        getMaxSteerAngle(),  //20
        m_speed,  //21
        m_vehicle->getWheelInfo(0).m_steering,  //23
        m_vehicle->getWheelInfo(1).m_steering,  //24
        StkTime::getRealTime()
        );
#endif

    // if its view is blocked by plunger, decrease remaining time
    if(m_view_blocked_by_plunger > 0)
    {
        m_view_blocked_by_plunger -= ticks;
        //unblock the view if kart just became shielded
        if(isShielded())
            m_view_blocked_by_plunger = 0;
    }

    // Decrease the remaining invulnerability time
    if(m_invulnerable_ticks>0)
        m_invulnerable_ticks -= ticks;

    if (!RewindManager::get()->isRewinding())
        m_slipstream->update(ticks);
    m_slipstream->updateSpeedIncrease();

    // TODO: hiker said this probably will be moved to btKart or so when updating bullet engine.
    // Neutralize any yaw change if the kart leaves the ground, so the kart falls more or less
    // straight after jumping, but still allowing some "boat shake" (roll and pitch).
    // Otherwise many non perfect jumps end in a total roll over or a serious change of
    // direction, sometimes 90 or even full U turn (real but less fun for a karting game).
    // As side effect steering becames a bit less responsive (any wheel on air), but not too bad.
    if(!isOnGround()) {
        btVector3 speed = m_body->getAngularVelocity();
        speed.setX(speed.getX() * 0.95f);
        speed.setY(speed.getY() * 0.25f); // or 0.0f for sharp neutralization of yaw
        speed.setZ(speed.getZ() * 0.95f);
        m_body->setAngularVelocity(speed);

        // When the kart is jumping, linear damping reduces the falling speed
        // of a kart so much that it can appear to be in slow motion. So
        // disable linear damping if a kart is in the air
        m_body->setDamping(0, m_kart_properties->getStabilityChassisAngularDamping());
    }
    else
    {
        m_body->setDamping(m_kart_properties->getStabilityChassisLinearDamping(),
                           m_kart_properties->getStabilityChassisAngularDamping());
    }

    // Used to prevent creating a rescue animation after an explosion animation got deleted

    m_attachment->update(ticks);

    // Make sure that the ray doesn't hit the kart. This is done by
    // resetting the collision filter group, so that this collision
    // object is ignored during raycasting.
    short int old_group = 0;
    if (m_body->getBroadphaseHandle())
    {
        old_group = m_body->getBroadphaseHandle()->m_collisionFilterGroup;
        m_body->getBroadphaseHandle()->m_collisionFilterGroup = 0;
    }

    // After the physics step was done, the position of the wheels (as stored
    // in wheelInfo) is actually outdated, since the chassis was moved
    // according to the force acting from the wheels. So the center of the
    // chassis is not at the center of the wheels anymore, it is somewhat
    // moved forward (depending on speed and fps). In very extreme cases
    // (see bug 2246) the center of the chassis can actually be ahead of the
    // front wheels. So if we do a raycast to detect the terrain from the
    // current chassis, that raycast might be ahead of the wheels - which
    // results in incorrect rescues (the wheels are still on the ground,
    // but the raycast happens ahead of the front wheels and are over
    // a rescue texture).
    // To avoid this problem, we do the raycast for terrain detection from
    // the center of the 4 wheel positions (in world coordinates).

    if (!has_animation_before)
    {
        Vec3 from(0.0f, 0.0f, 0.0f);
        for (unsigned int i = 0; i < 4; i++)
            from += m_vehicle->getWheelInfo(i).m_raycastInfo.m_hardPointWS;

        // Add a certain epsilon (0.3) to the height of the kart. This avoids
        // problems of the ray being cast from under the track (which happened
        // e.g. on tux tollway when jumping down from the ramp, when the chassis
        // partly tunnels through the track). While tunneling should not be
        // happening (since Z velocity is clamped), the epsilon is left in place
        // just to be on the safe side (it will not hit the chassis itself).
        from = from/4 + (getTrans().getBasis() * Vec3(0.0f, 0.3f, 0.0f));

        m_terrain_info->update(getTrans().getBasis(), from);
    }
    else
    {
        // Use kart transform directly as wheel info is not updated when
        // there is an animation
        m_terrain_info->update(getTrans().getBasis(),
            getXYZ() + getTrans().getBasis().getColumn(1) * 0.1f);
    }

    if (m_body->getBroadphaseHandle())
        m_body->getBroadphaseHandle()->m_collisionFilterGroup = old_group;

    // Check if a kart is (nearly) upside down and not moving much -->
    // automatic rescue
    // But only do this if auto-rescue is enabled (i.e. it will be disabled in
    // battle mode), and the material the kart is driving on does not have
    // gravity (which atm affects the roll angle).

    // To be used later
    float dist_to_sector = 0.0f;
    LinearWorld* lw = dynamic_cast<LinearWorld*>(World::getWorld());
    if (lw && DriveGraph::get())
    {
        const int sector =
            lw->getTrackSector(getWorldKartId())->getCurrentGraphNode();
        dist_to_sector = getXYZ().distance
            (DriveGraph::get()->getNode(sector)->getCenter());

        const Vec3& quad_normal = DriveGraph::get()->getNode(sector)
            ->getNormal();
        const btQuaternion& q = getTrans().getRotation();
        const float roll = quad_normal.angle
               ((Vec3(0, 1, 0).rotate(q.getAxis(), q.getAngle())));

        if (Track::getCurrentTrack()->isAutoRescueEnabled() &&
            (!m_terrain_info->getMaterial() ||
            !m_terrain_info->getMaterial()->hasGravity()) &&
            !has_animation_before && fabs(roll) > 60 * DEGREE_TO_RAD &&
            fabs(getSpeed()) < 3.0f)
        {
            RescueAnimation::create(this, /*is_auto_rescue*/true);
            m_last_factor_engine_sound = 0.0f;
        }
    }

    // Update physics from newly updated material
    PROFILER_PUSH_CPU_MARKER("Kart::updatePhysics", 0x60, 0x34, 0x7F);
    const Material* material = m_terrain_info->getMaterial();

    // First update the gravity of the kart, as updateSliding in updatePhysics
    // need the newly set gravity to test for sliding.
    if (!m_flying)
    {
        float g = Track::getCurrentTrack()->getGravity();
        Vec3 gravity(0.0f, -g, 0.0f);
        btRigidBody *body = getVehicle()->getRigidBody();

        // If the material should overwrite the gravity,
        if (material && material->hasGravity())
        {
            Vec3 normal = m_terrain_info->getNormal();
            gravity = normal * -g;
        }

        body->setGravity(gravity);
    }
    updatePhysics(ticks);
    PROFILER_POP_CPU_MARKER();

    if(!m_controls.getFire()) m_fire_clicked = 0;

    if(m_controls.getFire() && !m_fire_clicked && !m_kart_animation)
    {
        if (m_powerup->getType() != PowerupManager::POWERUP_NOTHING)
        {
            setLastUsedPowerup(m_powerup->getType());
        }
        // use() needs to be called even if there currently is no collecteable
        // since use() can test if something needs to be switched on/off.
        if (!World::getWorld()->isStartPhase())
            m_powerup->use();
        else
        {
            if(!getKartAnimation())
                beep();
        }
        World::getWorld()->onFirePressed(getController());
        m_fire_clicked = 1;
    }

#undef XX
#ifdef XX
    Log::verbose("physicsafter", "%s t %f %d xyz(9-11) %f %f %f %f %f %f "
        "v(16-18) %f %f %f steerf(20) %f maxangle(22) %f speed(24) %f "
        "steering(26-27) %f %f clock(29) %lf skidstate(31) %d factor(33) %f "
        "maxspeed(35) %f engf(37) %f braketick(39) %d brakes(41) %d heading(43) %f "
        "bubticks(45) %d",
        getIdent().c_str(),
        World::getWorld()->getTime(), World::getWorld()->getTicksSinceStart(),
        getXYZ().getX(), getXYZ().getY(), getXYZ().getZ(),
        m_body->getWorldTransform().getOrigin().getX(),
        m_body->getWorldTransform().getOrigin().getY(),
        m_body->getWorldTransform().getOrigin().getZ(),
        getVelocity().getX(), getVelocity().getY(), getVelocity().getZ(),  //16-18
        m_skidding->getSteeringFraction(), //20
        getMaxSteerAngle(),  //22
        m_speed,  //24
        m_vehicle->getWheelInfo(0).m_steering,  //26
        m_vehicle->getWheelInfo(1).m_steering,  //27
        StkTime::getRealTime(),  //29
        m_skidding->getSkidState(), //31
        m_skidding->getSkidFactor(),    //33
        m_max_speed->getCurrentMaxSpeed(),
        m_max_speed->getCurrentAdditionalEngineForce(),  // 37
        m_brake_ticks, //39
        m_controls.getButtonsCompressed(),  //41
        getHeading(),  //43
        m_bubblegum_ticks // 45
    );
#endif

    PROFILER_PUSH_CPU_MARKER("Kart::Update (material)", 0x60, 0x34, 0x7F);
    if (!material)   // kart falling off the track
    {
        // let kart fall a bit before rescuing
        const Vec3 *min, *max;
        Track::getCurrentTrack()->getAABB(&min, &max);

        if((min->getY() - getXYZ().getY() > 17 || dist_to_sector > 25) && !m_flying &&
           !has_animation_before)
        {
            RescueAnimation::create(this);
            m_last_factor_engine_sound = 0.0f;
        }
    }
    else
    {
        if (!has_animation_before && material->isDriveReset() && isOnGround())
        {
            RescueAnimation::create(this);
            m_last_factor_engine_sound = 0.0f;
        }
        else if(material->isZipper()     && isOnGround())
        {
            handleZipper(material);
            showZipperFire();
        }
        else
        {
            m_max_speed->setSlowdown(MaxSpeed::MS_DECREASE_TERRAIN,
                                     material->getMaxSpeedFraction(),
                                     material->getSlowDownTicks()    );
#ifdef DEBUG
            if(UserConfigParams::m_material_debug)
            {
                Log::info("Kart","World %d %s\tfraction %f\ttime %d.",
                       World::getWorld()->getTicksSinceStart(),
                       material->getTexFname().c_str(),
                       material->getMaxSpeedFraction(),
                       material->getSlowDownTicks()       );
            }
#endif
        }
    }   // if there is material
    PROFILER_POP_CPU_MARKER();

    Track::getCurrentTrack()->getItemManager()->checkItemHit(this);

    const bool emergency = has_animation_before;

    if (emergency)
    {
        m_view_blocked_by_plunger = 0;
        if (m_flying)
        {
            stopFlying();
            m_flying = false;
        }
    }

    if (RewindManager::get()->isRewinding())
        return;
    // Remove the shadow if the kart is not on the ground (if a kart
    // is rescued isOnGround might still be true, since the kart rigid
    // body was removed from the physics, but still retain the old
    // values for the raycasts).
    if (!isOnGround() && !has_animation_before)
    {
        const Material *m      = getMaterial();
        const Material *last_m = getLastMaterial();

        // A jump starts only the kart isn't already jumping, is on a new
        // (or no) texture.
        if (!m_is_jumping && last_m && last_m != m &&
            m_kart_model->getAnimation() == KartModel::AF_DEFAULT)
        {
            float v = getVelocity().getY();
            float force = Track::getCurrentTrack()->getGravity();
            // Velocity / force is the time it takes to reach the peak
            // of the jump (i.e. when vertical speed becomes 0). Assuming
            // that jump start height and end height are the same, it will
            // take the same time again to reach the bottom
            float t = 2.0f * v/force;

            // Jump if either the jump is estimated to be long enough, or
            // the texture has the jump property set.
            if (t > m_kart_properties->getJumpAnimationTime() ||
                last_m->isJumpTexture())
            {
                m_kart_model->setAnimation(KartModel::AF_JUMP_START);
            }

            m_is_jumping = true;
        }
    }
    else if (m_is_jumping)
    {
        // Kart touched ground again
        m_is_jumping = false;
        m_kart_model->setAnimation(KartModel::AF_DEFAULT);

        if (!GUIEngine::isNoGraphics() && !has_animation_before)
        {
            HitEffect *effect =  new Explosion(getXYZ(), "jump",
                                              "jump_explosion.xml");
            ProjectileManager::get()->addHitEffect(effect);
        }
    }

}   // update

//-----------------------------------------------------------------------------
/** Updates the local speed based on the current physical velocity. The value
 *  is smoothed exponentially to avoid camera stuttering (camera distance
 *  is dependent on speed)
 */
void Kart::updateSpeed()
{
    // Compute the speed of the kart. Smooth it with previous speed to make
    // the camera smoother (because of capping the speed in m_max_speed
    // the speed value jitters when approaching maximum speed. This results
    // in the distance between kart and camera to jitter as well (typically
    // only in the order of centimetres though). Smoothing the speed value
    // gets rid of this jitter, and also r
    m_speed = getVehicle()->getRigidBody()->getLinearVelocity().length();

    // calculate direction of m_speed
    const btTransform& chassisTrans = getVehicle()->getChassisWorldTransform();
    btVector3 forwardW(
        chassisTrans.getBasis()[0][2],
        chassisTrans.getBasis()[1][2],
        chassisTrans.getBasis()[2][2]);

    // In theory <0 should be sufficient, but floating point errors can cause
    // flipping from +eps to -eps and back, resulting in animation flickering
    // if the kart has backpedal animations.
    if (forwardW.dot(getVehicle()->getRigidBody()->getLinearVelocity()) 
        < btScalar(-0.01f))
    {
        m_speed = -m_speed;
    }

    // At low velocity, forces on kart push it back and forth so we ignore this
    // - quick'n'dirty workaround for bug 1776883
    if (fabsf(m_speed) < 0.2f                                   ||
        dynamic_cast<RescueAnimation*>   ( getKartAnimation() ) ||
        dynamic_cast<ExplosionAnimation*>( getKartAnimation() )    )
    {
        m_speed          = 0;
    }
}   // updateSpeed

//-----------------------------------------------------------------------------
/** Show fire to go with a zipper.
 */
void Kart::showZipperFire()
{
    m_kart_gfx->setCreationRateAbsolute(KartGFX::KGFX_ZIPPER, 800.0f);
}

//-----------------------------------------------------------------------------
/** Squashes this kart: it will scale the kart in up direction, and causes
 *  a slowdown while this kart is squashed.
 *  Returns true if the squash is successful, false otherwise.
 *  \param time How long the kart will be squashed. A value of 0 will reset
 *         the kart to be unsquashed.
 *  \param slowdown Reduction of max speed.
 */
bool Kart::setSquash(float time, float slowdown)
{
    if (isInvulnerable() || getKartAnimation()) return false;

    if (isShielded())
    {
        decreaseShieldTime();
        return false;
    }

    if(m_attachment->getType()==Attachment::ATTACH_BOMB && time>0)
    {
        ExplosionAnimation::create(this);
        return true;
    }

    m_max_speed->setSlowdown(MaxSpeed::MS_DECREASE_SQUASH, slowdown,
                             stk_config->time2Ticks(0.1f), 
                             stk_config->time2Ticks(time));
    return true;
}   // setSquash

//-----------------------------------------------------------------------------
void Kart::setSquashGraphics()
{
#ifndef SERVER_ONLY
    if (isGhostKart() || GUIEngine::isNoGraphics()) return;

    m_node->setScale(core::vector3df(1.0f, 0.5f, 1.0f));
    if (m_vehicle->getNumWheels() > 0)
    {
        if (!m_wheel_box)
        {
            m_wheel_box = irr_driver->getSceneManager()
                ->addDummyTransformationSceneNode(m_node);
        }
        scene::ISceneNode **wheels = m_kart_model->getWheelNodes();
        for (int i = 0; i < 4 && i < m_vehicle->getNumWheels(); i++)
        {
            if (wheels[i])
                wheels[i]->setParent(m_wheel_box);
        }
        m_wheel_box->getRelativeTransformationMatrix()
            .setScale(core::vector3df(1.0f, 2.0f, 1.0f));
    }
#endif
}   // setSquashGraphics

//-----------------------------------------------------------------------------
void Kart::unsetSquash()
{
#ifndef SERVER_ONLY
    if (isGhostKart() || GUIEngine::isNoGraphics()) return;

    m_node->setScale(core::vector3df(1.0f, 1.0f, 1.0f));
    if (m_vehicle && m_vehicle->getNumWheels() > 0)
    {
        scene::ISceneNode** wheels = m_kart_model->getWheelNodes();
        scene::ISceneNode* node = m_kart_model->getAnimatedNode() ?
                                  m_kart_model->getAnimatedNode() : m_node;

        for (int i = 0; i < 4 && i < m_vehicle->getNumWheels(); i++)
        {
            if (wheels[i])
            {
                wheels[i]->setParent(node);
            }
        }
    }
#endif
}   // unsetSquash

//-----------------------------------------------------------------------------
/** Returns if the kart is currently being squashed
  */
bool Kart::isSquashed() const
{
    return
        m_max_speed->isSpeedDecreaseActive(MaxSpeed::MS_DECREASE_SQUASH) == 1;
}   // setSquash

//-----------------------------------------------------------------------------
/** Plays any terrain specific sound effect.
 */
void Kart::handleMaterialSFX()
{
    // If a terrain specific sfx is already being played, when a new
    // terrain is entered, an old sfx should be finished (once, not
    // looped anymore of course). The m_terrain_sound is then copied
    // to a m_previous_terrain_sound, for which looping is disabled.
    // In case that three sfx needed to be played (i.e. a previous is
    // playing, a current is playing, and a new terrain with sfx is
    // entered), the oldest (previous) sfx is stopped and deleted.

    // FIXME: if there are already two sfx playing, don't add another
    // one. This should reduce the performance impact when driving 
    // on the bridge in Cocoa.
    const Material* material =
        isOnGround() ? m_terrain_info->getMaterial() : NULL;

    // We can not use getLastMaterial() since, since the last material might
    // be updated several times during the physics updates, not indicating
    // that we have reached a new material with regards to the sound effect.
    // So we separately save the material last used for a sound effect and
    // then use this for comparison.
    if(m_last_sound_material!=material)
    {
        // First stop any previously playing terrain sound
        // and remove it, so that m_previous_terrain_sound
        // can be used again.
        if(m_previous_terrain_sound)
        {
            m_previous_terrain_sound->deleteSFX();
        }

        // Disable looping for the current terrain sound, and
        // make it the previous terrain sound.
        if (m_terrain_sound) m_terrain_sound->setLoop(false);
        m_previous_terrain_sound = m_terrain_sound;

        const std::string &sound_name = material ? material->getSFXName() : "";

        // In multiplayer mode sounds are NOT positional, because we have
        // multiple listeners. This would make the sounds of all AIs be
        // audible at all times. So silence AI karts.
        if (!sound_name.empty() && (RaceManager::get()->getNumPlayers()==1 ||
                                    m_controller->isLocalPlayerController() ) )
        {
            m_terrain_sound = SFXManager::get()->createSoundSource(sound_name);
            m_terrain_sound->play();
            m_terrain_sound->setLoop(true);
        }
        else
        {
            m_terrain_sound = NULL;
        }
    }

    // Check if a previous terrain sound (now not looped anymore)
    // is finished and can be deleted.
    if(m_previous_terrain_sound &&
        m_previous_terrain_sound->getStatus()==SFXBase::SFX_STOPPED)
    {
        // We don't modify the position of m_previous_terrain_sound
        // anymore, so that it keeps on playing at the place where the
        // kart left the material.
        m_previous_terrain_sound->deleteSFX();
        m_previous_terrain_sound = NULL;
    }

    bool m_schedule_pause = m_flying ||
                        dynamic_cast<RescueAnimation*>(getKartAnimation()) ||
                        dynamic_cast<ExplosionAnimation*>(getKartAnimation()) ||
                        World::getWorld()->getPhase() == World::IN_GAME_MENU_PHASE;

    // terrain sound is not necessarily a looping sound so check its status before
    // setting its speed, to avoid 'ressuscitating' sounds that had already stopped
    if(m_terrain_sound && 
        (m_terrain_sound->getStatus()==SFXBase::SFX_PLAYING ||
         m_terrain_sound->getStatus()==SFXBase::SFX_PAUSED)    )
    {
        m_terrain_sound->setPosition(getSmoothedXYZ());
        if(material)
            material->setSFXSpeed(m_terrain_sound, m_speed, m_schedule_pause);
    }

    m_last_sound_material = material;
}   // handleMaterialSFX

//-----------------------------------------------------------------------------
/** Handles material specific GFX, mostly particle effects. Particle
 *  effects can be triggered by two different situations: either
 *  because a kart drives on top of a terrain with a special effect,
 *  or because the kart is driving or falling under a surface (e.g.
 *  water), and the terrain effect is coming from that surface. Those
 *  effects are exclusive - you either get the effect from the terrain
 *  you are driving on, or the effect from a surface the kart is
 *  (partially) under. The surface effect is triggered, if either the
 *  kart is falling, or if the surface the kart is driving on has
 *  the 'isBelowSurface' property set. This function is called once
 *  per rendered frame from updateGraphics().
 *  \param dt Time step size.
 */
void Kart::handleMaterialGFX(float dt)
{
    const Material *material = getMaterial();

    // First test: give the terrain effect, if the kart is
    // on top of a surface (i.e. not falling), actually touching
    // something with the wheels, and the material has not the
    // below surface property set.
    if (material && isOnGround() && !material->isBelowSurface() &&
        !getKartAnimation()      && UserConfigParams::m_particles_effects > 1)
    {
        // Make sure camera is reset if on ground, see #2916 and #4737
        for (unsigned i = 0; i < Camera::getNumCameras(); i++)
        {
            if (material->isDriveReset())
                break;
            Camera *camera = Camera::getCamera(i);
            if (camera->getKart() != this)
                continue;
            if (camera->getMode() == Camera::CM_FALLING)
                camera->setMode(Camera::CM_NORMAL);
        }   // for i in all cameras for this kart

        // Get the appropriate particle data depending on
        // wether the kart is skidding or driving.
        const ParticleKind* pk =
            material->getParticlesWhen(m_skidding->isSkidding()
                                                    ? Material::EMIT_ON_SKID
                                                    : Material::EMIT_ON_DRIVE);
        if(!pk)
        {
            // Disable potentially running particle effects
            m_kart_gfx->setCreationRateAbsolute(KartGFX::KGFX_TERRAIN, 0);
            return;  // no particle effect, return
        }
        m_kart_gfx->updateTerrain(pk);
        return;
    }

    // Now the kart is either falling, or driving on a terrain which
    // has the 'below surface' flag set. Detect if there is a surface
    // on top of the kart.
    // --------------------------------------------------------------
    if (m_controller->isLocalPlayerController() && !hasFinishedRace())
    {
        bool falling = material && material->hasFallingEffect() && !m_flying;
        if (falling)
        {
            m_falling_time -= dt;
            if (m_falling_time < 0)
                m_falling_time = 0;
        }
        else
            m_falling_time = 0.35f;

        for(unsigned int i=0; i<Camera::getNumCameras(); i++)
        {
            Camera *camera = Camera::getCamera(i);
            if(camera->getKart()!=this) continue;

            if (falling && m_falling_time <= 0)
            {
                camera->setMode(Camera::CM_FALLING);
            }
            else if (camera->getMode() != Camera::CM_NORMAL &&
                     camera->getMode() != Camera::CM_REVERSE)
            {
                camera->setMode(Camera::CM_NORMAL);
            }
        }   // for i in all cameras for this kart
    }   // camera != final camera

    if (UserConfigParams::m_particles_effects < 2)
        return;

    // Use the middle of the contact points of the two rear wheels
    // as the point from which to cast the ray upwards
    const btWheelInfo::RaycastInfo &ri2 =
        getVehicle()->getWheelInfo(2).m_raycastInfo;
    const btWheelInfo::RaycastInfo &ri3 =
        getVehicle()->getWheelInfo(3).m_raycastInfo;
    Vec3 from = (ri2.m_contactPointWS + ri3.m_contactPointWS)*0.5f;
    Vec3 xyz;
    const Material *surface_material;
    if(!m_terrain_info->getSurfaceInfo(from, &xyz, &surface_material))
    {
        m_kart_gfx->setCreationRateAbsolute(KartGFX::KGFX_TERRAIN, 0);
        return;
    }
    const ParticleKind *pk =
        surface_material->getParticlesWhen(Material::EMIT_ON_DRIVE);

    if(!pk || m_flying || dynamic_cast<RescueAnimation*>(getKartAnimation()))
        return;

    // Now the kart is under a surface, and there is a surface effect
    // --------------------------------------------------------------
    m_kart_gfx->setParticleKind(KartGFX::KGFX_TERRAIN, pk);
    m_kart_gfx->setXYZ(KartGFX::KGFX_TERRAIN, xyz);

    const float distance = xyz.distance2(from);
    float ratio;
    if      (distance < 2.0f) ratio = 1.0f;
    else if (distance < 4.0f) ratio = (4.0f-distance)*0.5f;
    else                      ratio = -1.0f;  // No more particles
    m_kart_gfx->setCreationRateRelative(KartGFX::KGFX_TERRAIN, ratio);

    // Play special sound effects for this terrain
    // -------------------------------------------
    const std::string &s = surface_material->getSFXName();
    if (s != "" && !dynamic_cast<RescueAnimation*>(getKartAnimation())&&
        (m_terrain_sound == NULL ||
         m_terrain_sound->getStatus() == SFXBase::SFX_STOPPED))
    {
        if (m_previous_terrain_sound) m_previous_terrain_sound->deleteSFX();
        m_previous_terrain_sound = m_terrain_sound;
        if(m_previous_terrain_sound)
            m_previous_terrain_sound->setLoop(false);

        m_terrain_sound = SFXManager::get()->createSoundSource(s);
        m_terrain_sound->play();
        m_terrain_sound->setLoop(false);
    }

}   // handleMaterialGFX

//-----------------------------------------------------------------------------
/** Sets zipper time, and apply one time additional speed boost. It can be
 *  used with a specific material, in which case the zipper parmaters are
 *  taken from this material (parameters that are <0 will be using the
 *  kart-specific values from kart-properties.
 *  \param material If not NULL, will be used to determine the zipper
 *                  parameters, otherwise the defaults from kart properties
 *                  will be used.
 * \param play_sound If true this will cause a sfx to be played even if the
 *                  terrain hasn't changed. It is used by the zipper powerup.
 */
void Kart::handleZipper(const Material *material, bool play_sound)
{
    /** The additional speed allowed on top of the kart-specific maximum kart
     *  speed. */
    float max_speed_increase;

    /**Time the zipper stays activated. */
    float duration;
    /** A one time additional speed gain - the kart will instantly add this
     *  amount of speed to its current speed. */
    float speed_gain;
    /** Time it takes for the zipper advantage to fade out. */
    float fade_out_time;
    /** Additional engine force. */
    float engine_force;

    if(material)
    {
        material->getZipperParameter(&max_speed_increase, &duration,
                                     &speed_gain, &fade_out_time, &engine_force);
        if(max_speed_increase<0)
            max_speed_increase = m_kart_properties->getZipperMaxSpeedIncrease();
        if(duration<0)
            duration           = m_kart_properties->getZipperDuration();
        if(speed_gain<0)
            speed_gain         = m_kart_properties->getZipperSpeedGain();
        if(fade_out_time<0)
            fade_out_time      = m_kart_properties->getZipperFadeOutTime();
        if(engine_force<0)
            engine_force       = m_kart_properties->getZipperForce();
    }
    else
    {
        max_speed_increase = m_kart_properties->getZipperMaxSpeedIncrease();
        duration           = m_kart_properties->getZipperDuration();
        speed_gain         = m_kart_properties->getZipperSpeedGain();
        fade_out_time      = m_kart_properties->getZipperFadeOutTime();
        engine_force       = m_kart_properties->getZipperForce();
    }
    // Ignore a zipper that's activated while braking
    if(m_controls.getBrake() || m_speed<0) return;

    m_max_speed->instantSpeedIncrease(MaxSpeed::MS_INCREASE_ZIPPER,
                                     max_speed_increase, speed_gain,
                                     engine_force,
                                     stk_config->time2Ticks(duration),
                                     stk_config->time2Ticks(fade_out_time));
    // Play custom character sound (weee!)
    int zipper_ticks = World::getWorld()->getTicksSinceStart();
    if (zipper_ticks > m_ticks_last_zipper)
    {
        m_ticks_last_zipper = zipper_ticks;
        playCustomSFX(SFXManager::CUSTOM_ZIPPER);
        m_controller->handleZipper(play_sound);
    }

}   // handleZipper

// -----------------------------------------------------------------------------
/** Updates the current nitro status.
 *  \param ticks Number of physics time steps - should be 1.
 */
void Kart::updateNitro(int ticks)
{
    if (m_collected_energy == 0)
        m_min_nitro_ticks = 0;

    if (m_controls.getNitro() && m_min_nitro_ticks <= 0 && m_collected_energy > 0)
    {
        m_min_nitro_ticks = m_kart_properties->getNitroMinConsumptionTicks();
        float min_consumption = m_min_nitro_ticks * m_consumption_per_tick;
        m_energy_to_min_ratio = std::min<float>(1, m_collected_energy/min_consumption);
    }
    if (m_min_nitro_ticks > 0)
    {
        m_min_nitro_ticks -= ticks;

        // when pressing the key, don't allow the min time to go under zero.
        // If it went under zero, it would be reset
        // As the time deduction happens before, it can be an arbitrarily
        // small number > 0. Smaller means more responsive controls.
        if (m_controls.getNitro() && m_min_nitro_ticks <= 0)
            m_min_nitro_ticks = 1;
    }

    bool rewinding = RewindManager::get()->isRewinding();
    bool increase_speed = (m_min_nitro_ticks > 0 && isOnGround());
    if (!increase_speed && m_min_nitro_ticks <= 0)
    {
        if (m_nitro_sound->getStatus() == SFXBase::SFX_PLAYING && !rewinding)
            m_nitro_sound->stop();
        return;
    }


    m_collected_energy -= m_consumption_per_tick*ticks;
    if (m_collected_energy < 0)
    {
        if(m_nitro_sound->getStatus() == SFXBase::SFX_PLAYING && !rewinding)
            m_nitro_sound->stop();
        m_collected_energy = 0;
        return;
    }

    if (increase_speed)
    {
        if(m_nitro_sound->getStatus() != SFXBase::SFX_PLAYING && !rewinding)
            m_nitro_sound->play();

        m_max_speed->increaseMaxSpeed(MaxSpeed::MS_INCREASE_NITRO,
            m_kart_properties->getNitroMaxSpeedIncrease(),
            m_kart_properties->getNitroEngineForce(),
            stk_config->time2Ticks(m_kart_properties->getNitroDuration()*m_energy_to_min_ratio),
            stk_config->time2Ticks(m_kart_properties->getNitroFadeOutTime()));
    }
    else
    {
        if(m_nitro_sound->getStatus() == SFXBase::SFX_PLAYING && !rewinding)
            m_nitro_sound->stop();
    }
}   // updateNitro

// -----------------------------------------------------------------------------
/** Activates a slipstream effect */
void Kart::setSlipstreamEffect(float f)
{
    m_kart_gfx->setCreationRateAbsolute(KartGFX::KGFX_ZIPPER, f);
}   // setSlipstreamEffect

// -----------------------------------------------------------------------------
/** Called when the kart crashes against another kart.
 *  \param k The kart that was hit.
 *  \param update_attachments If true the attachment of this kart and the
 *          other kart hit will be updated (e.g. bombs will be moved)
 */
void Kart::crashed(AbstractKart *k, bool update_attachments)
{
    if(update_attachments)
    {
        assert(k);
        getAttachment()->handleCollisionWithKart(k);
    }
    m_controller->crashed(k);
    playCrashSFX(NULL, k);
}   // crashed(Kart, update_attachments

// -----------------------------------------------------------------------------
/** Kart hits the track with a given material.
 *  \param m Material hit, can be NULL if no specific material exists.
 *  \param normal The normal of the hit (used to push a kart back, which avoids
 *         that karts sometimes can get stuck).
 */
void Kart::crashed(const Material *m, const Vec3 &normal)
{
    if (m && !(m->getCollisionReaction() == Material::RESCUE))
        playCrashSFX(m, NULL);
#ifdef DEBUG
    // Simple debug output for people playing without sound.
    // This makes it easier to see if a kart hit the track (esp.
    // after a jump).
    // FIXME: This should be removed once the physics are fixed.
    if(UserConfigParams::m_physics_debug)
    {
        // Add a counter to make it easier to see if a new line of
        // output was added.
        static int counter=0;
        Log::info("Kart","Kart %s hit track: %d material %s.",
               getIdent().c_str(), counter++,
               m ? m->getTexFname().c_str() : "None");
    }
#endif

    const LinearWorld *lw = dynamic_cast<LinearWorld*>(World::getWorld());
    if(m_kart_properties->getTerrainImpulseType()
                             ==KartProperties::IMPULSE_NORMAL &&
        m_vehicle->getCentralImpulseTicks()<=0                     )
    {
        // Restrict impule to plane defined by gravity (i.e. X/Z plane).
        // This avoids the problem that karts can be pushed up, e.g. above
        // a fence.
        btVector3 gravity = m_body->getGravity();
        gravity.normalize();
        Vec3 impulse =  normal - gravity* btDot(normal, gravity);
        if(impulse.getX() || impulse.getZ())
            impulse.normalize();
        else
            impulse = Vec3(0, 0, -1); // Arbitrary
        // Impulse depends of kart speed - and speed can be negative
        // If the speed is too low, karts can still get stuck into a wall
        // so make sure there is always enough impulse to avoid this
        float abs_speed = fabsf(getSpeed());
        impulse *= ( abs_speed<10 ? 10.0f : sqrt(abs_speed) )
                 * m_kart_properties->getCollisionTerrainImpulse();
        m_bounce_back_ticks = 0;
        impulse = Vec3(0, 0, 0);
        //m_vehicle->setTimedCentralImpulse(0.1f, impulse);
        m_vehicle->setTimedCentralImpulse(0, impulse);
    }
    // If there is a quad graph, push the kart towards the previous
    // graph node center (we have to use the previous point since the
    // kart might have only now reached the new quad, meaning the kart
    // would be pushed forward).
    else if(m_kart_properties->getTerrainImpulseType()
                                 ==KartProperties::IMPULSE_TO_DRIVELINE &&
            lw && m_vehicle->getCentralImpulseTicks()<=0 &&
            Track::getCurrentTrack()->isPushBackEnabled())
    {
        int sector = lw->getSectorForKart(this);
        if(sector!=Graph::UNKNOWN_SECTOR)
        {
            // Use the first predecessor node, which is the most
            // natural one (i.e. the one on the main driveline).
            const DriveNode* dn = DriveGraph::get()->getNode(
                DriveGraph::get()->getNode(sector)->getPredecessor(0));
            Vec3 impulse = dn->getCenter() - getXYZ();
            impulse.setY(0);
            if(impulse.getX() || impulse.getZ())
                impulse.normalize();
            else
                impulse = Vec3(0, 0, -1); // Arbitrary
            impulse *= m_kart_properties->getCollisionTerrainImpulse();
            m_bounce_back_ticks = (uint8_t)stk_config->time2Ticks(0.2f);
            m_vehicle->setTimedCentralImpulse(
                (uint16_t)stk_config->time2Ticks(0.1f), impulse);
        }

    }
    /** If a kart is crashing against the track, the collision is often
     *  reported more than once, resulting in a machine gun effect, and too
     *  long disabling of the engine. Therefore, this reaction is disabled
     *  for 0.5 seconds after a crash.
     */
    if(m && m->getCollisionReaction() != Material::NORMAL &&
        !getKartAnimation())
    {
#ifndef SERVER_ONLY
        std::string particles = m->getCrashResetParticles();
        if (!GUIEngine::isNoGraphics() &&
            particles.size() > 0 && UserConfigParams::m_particles_effects > 0)
        {
            ParticleKind* kind =
                ParticleKindManager::get()->getParticles(particles);
            if (kind != NULL)
            {
                if (m_collision_particles == NULL)
                {
                    Vec3 position(-getKartWidth()*0.35f, 0.06f,
                                  getKartLength()*0.5f);
                    m_collision_particles  =
                        new ParticleEmitter(kind, position, getNode());
                }
                else
                {
                    m_collision_particles->setParticleType(kind);
                }
            }
            else
            {
                Log::error("Kart","Unknown particles kind <%s> in material "
                                "crash-reset properties\n", particles.c_str());
            }
        }
#endif
        if (m->getCollisionReaction() == Material::RESCUE)
        {
            RescueAnimation::create(this);
            m_last_factor_engine_sound = 0.0f;
        }
        else if (m->getCollisionReaction() == Material::PUSH_BACK)
        {
            // This variable is set to 0.2 in case of a kart-terrain collision
            if (m_bounce_back_ticks <= (uint8_t)stk_config->time2Ticks(0.2f))
            {
                btVector3 push = m_body->getLinearVelocity().normalized();
                push[1] = 0.1f;
                m_body->applyCentralImpulse( -4000.0f*push );
                m_bounce_back_ticks = (uint8_t)stk_config->time2Ticks(2.0f);
            }   // if m_bounce_back_ticks <= 0.2f
        }   // if (m->getCollisionReaction() == Material::PUSH_BACK)
    }   // if(m && m->getCollisionReaction() != Material::NORMAL &&
        //   !getKartAnimation())
    m_controller->crashed(m);
}   // crashed(Material)

// -----------------------------------------------------------------------------
/** Common code used when a kart or a material was hit.
 * @param m The material collided into, or NULL if none
 * @param k The kart collided into, or NULL if none
 */
void Kart::playCrashSFX(const Material* m, AbstractKart *k)
{
    int ticks_since_start = World::getWorld()->getTicksSinceStart();
    if(ticks_since_start-m_ticks_last_crash < 60) return;

    m_ticks_last_crash = ticks_since_start;
    // After a collision disable the engine for a short time so that karts
    // can 'bounce back' a bit (without this the engine force will prevent
    // karts from bouncing back, they will instead stuck towards the obstable).
    if(m_bounce_back_ticks == 0)
    {
        if (getVelocity().length()> 0.555f)
        {
            const float speed_for_max_volume = 15; //The speed at which the sound plays at maximum volume
            const float max_volume = 1; //The maximum volume a sound is played at 
            const float min_volume = 0.2f; //The minimum volume a sound is played at 
            
            float volume; //The volume the crash sound will be played at
            
            if (k == NULL) //Collision with wall
            {
                volume = sqrt( abs(m_speed / speed_for_max_volume));
            }
            else
            {
                const Vec3 ThisKartVelocity = getVelocity();
                const Vec3 OtherKartVelocity = k->getVelocity();
                const Vec3 VelocityDifference = ThisKartVelocity - OtherKartVelocity;
                const float LengthOfDifference = VelocityDifference.length();
            
                volume = sqrt( abs(LengthOfDifference / speed_for_max_volume));
            }
            
            if (volume > max_volume) { volume = max_volume; }
            else if (volume < min_volume) { volume = min_volume; }

            SFXBase* crash_sound_emitter = getNextEmitter();
            crash_sound_emitter->setVolume(volume);
            
            // In case that the sfx is longer than 0.5 seconds, only play it if
            // it's not already playing.
            if (isShielded() || (k != NULL && k->isShielded()))
            {
                crash_sound_emitter->play(getSmoothedXYZ(), m_boing_sound);
            }
            else
            {
                int idx = rand() % CRASH_SOUND_COUNT;

                SFXBuffer* buffer = m_crash_sounds[idx];
                crash_sound_emitter->play(getSmoothedXYZ(), buffer);
            }
        }    // if lin_vel > 0.555
    }   // if m_bounce_back_ticks == 0
}   // playCrashSFX

// -----------------------------------------------------------------------------
/** Plays a beep sfx.
 */
void Kart::beep()
{
    // If the custom horn can't play (isn't defined) then play the default one
    if (!playCustomSFX(SFXManager::CUSTOM_HORN) &&
        !RewindManager::get()->isRewinding())
    {
        getNextEmitter()->play(getSmoothedXYZ(), m_horn_sound);
    }

} // beep

// -----------------------------------------------------------------------------
/*
    playCustomSFX()

    This function will play a particular character voice for this kart.  It
    returns whether or not a character voice sample exists for the particular
    event.  If there is no voice sample, a default can be played instead.

    Use entries from the CustomSFX enumeration as a parameter (see
    SFXManager::get().hpp).  eg. playCustomSFX(SFXManager::CUSTOM_CRASH)

    Obviously we don't want a certain character voicing multiple phrases
    simultaneously.  It just sounds bad.  There are two ways of avoiding this:

    1.  If there is already a voice sample playing for the character
        don't play another until it is finished.

    2.  If there is already a voice sample playing for the character
        stop the sample, and play the new one.

    Currently we're doing #2.

    rforder

*/

bool Kart::playCustomSFX(unsigned int type)
{
    // (TODO: add back when properly done)
    return false;

    /*
    bool ret = false;

    // Stop all other character voices for this kart before playing a new one
    // we don't want overlapping phrases coming from the same kart
    for (unsigned int n = 0; n < SFXManager::NUM_CUSTOMS; n++)
    {
        if (m_custom_sounds[n] != NULL)
        {
            // If the sound we're trying to play is already playing
            // don't stop it, we'll just let it finish.
            if (type != n) m_custom_sounds[n]->stop();
        }
    }

    if (type < SFXManager::NUM_CUSTOMS)
    {
        if (m_custom_sounds[type] != NULL)
        {
            ret = true;
            //printf("Kart SFX: playing %s for %s.\n",
            //    SFXManager::get()->getCustomTagName(type),
            //    m_kart_properties->getIdent().c_str());
            // If it's already playing, let it finish
            if (m_custom_sounds[type]->getStatus() != SFXManager::SFX_PLAYING)
            {
                m_custom_sounds[type]->play();
            }
        }
    }
    return ret;
     */
}
// ----------------------------------------------------------------------------
/** Updates the physics for this kart: computing the driving force, set
 *  steering, handles skidding, terrain impact on kart, ...
 *  \param ticks Number if physics time steps - should be 1.
 */
void Kart::updatePhysics(int ticks)
{
    if (m_controls.getAccel() > 0.0f &&
        World::getWorld()->getTicksSinceStart() == 1)
    {
        if (m_startup_boost > 0.0f)
        {
            m_kart_gfx->setCreationRateAbsolute(KartGFX::KGFX_ZIPPER,
                100.0f * m_startup_boost);
            m_max_speed->instantSpeedIncrease(MaxSpeed::MS_INCREASE_ZIPPER,
                0.9f * m_startup_boost, m_startup_boost,
                /*engine_force*/200.0f,
                /*duration*/stk_config->time2Ticks(5.0f),
                /*fade_out_time*/stk_config->time2Ticks(5.0f));
        }
    }
    if (m_bounce_back_ticks > 0)
        m_bounce_back_ticks -= ticks;

    updateEnginePowerAndBrakes(ticks);

    // apply flying physics if relevant
    if (m_flying)
        updateFlying();

    m_skidding->update(ticks, isOnGround(), m_controls.getSteer(),
                       m_controls.getSkidControl());
    if( ( m_skidding->getSkidState() == Skidding::SKID_ACCUMULATE_LEFT ||
          m_skidding->getSkidState() == Skidding::SKID_ACCUMULATE_RIGHT  ) &&
       !m_skidding->isJumping()                                              )
    {
        if(m_skid_sound && m_skid_sound->getStatus()!=SFXBase::SFX_PLAYING)
            m_skid_sound->play(getSmoothedXYZ());
    }
    else if(m_skid_sound && m_skid_sound->getStatus()==SFXBase::SFX_PLAYING)
    {
        m_skid_sound->stop();
    }

    float steering = getMaxSteerAngle() * m_skidding->getSteeringFraction();
    m_vehicle->setSteeringValue(steering, 0);
    m_vehicle->setSteeringValue(steering, 1);

    updateSliding();

    // Cap speed if necessary
    const Material *m = getMaterial();

    float min_speed =  m && m->isZipper() ? m->getZipperMinSpeed() : -1.0f;
    m_max_speed->setMinSpeed(min_speed);
    m_max_speed->update(ticks);

#ifdef XX
    Log::info("Kart","angVel %f %f %f heading %f suspension %f %f %f %f"
       ,m_body->getAngularVelocity().getX()
       ,m_body->getAngularVelocity().getY()
       ,m_body->getAngularVelocity().getZ()
       ,getHeading()
       ,m_vehicle->getWheelInfo(0).m_raycastInfo.m_suspensionLength
       ,m_vehicle->getWheelInfo(1).m_raycastInfo.m_suspensionLength
       ,m_vehicle->getWheelInfo(2).m_raycastInfo.m_suspensionLength
       ,m_vehicle->getWheelInfo(3).m_raycastInfo.m_suspensionLength
       );
#endif

}   // updatephysics

//-----------------------------------------------------------------------------
/** Adjust the engine sound effect depending on the speed of the kart. This 
 *  is called during updateGraphics, i.e. once per rendered frame only.
 *  \param dt Time step size.
 */
void Kart::updateEngineSFX(float dt)
{
    // Only update SFX during the last substep (otherwise too many SFX commands
    // in one frame), and if sfx are enabled
    if(!SFXManager::get()->sfxAllowed())
        return;
    
    if (m_skid_sound)
        m_skid_sound->setPosition(getSmoothedXYZ());
    if (m_nitro_sound)
        m_nitro_sound->setPosition(getSmoothedXYZ());

    if (!m_engine_sound)
        return;

    // when going faster, use higher pitch for engine
    if(isOnGround())
    {
        float max_speed = m_kart_properties->getEngineMaxSpeed();

        // Engine noise is based half in total speed, half in fake gears:
        // With a sawtooth graph like /|/|/| we get 3 even spaced gears,
        // ignoring the gear settings from stk_config, but providing a
        // good enough brrrBRRRbrrrBRRR sound effect. Speed factor makes
        // it a "staired sawtooth", so more acoustically rich.
        float f = max_speed > 0 ? m_speed/max_speed : 1.0f;
        // Speed at this stage is not yet capped, reduce the amount beyond 1
        if (f> 1.0f) f = 1.0f + (1.0f-1.0f/f);

        float fc = f;
        if (fc>1.0f) fc = 1.0f;
        float gears = 3.0f * fmod(fc, 0.333334f);
        assert(!std::isnan(f));
        m_last_factor_engine_sound = (0.9f*f + gears) * 0.35f;
        m_engine_sound->setSpeedPosition(0.6f + m_last_factor_engine_sound, getSmoothedXYZ());
    }
    else
      {
        // When flying, reduce progressively the sound engine (since we can't accelerate)
        m_last_factor_engine_sound *= (1.0f-0.1f*dt);
        m_engine_sound->setSpeedPosition(0.6f + m_last_factor_engine_sound, getSmoothedXYZ());
        if (m_speed < 0.1f) m_last_factor_engine_sound = 0.0f;
      }
}   // updateEngineSFX



//-----------------------------------------------------------------------------
/** Reduces the engine power according to speed
 *  
 *  TODO : find where the physics already apply a linear force decrease
 *  TODO : While this work fine, it should ideally be in physics
 *         However, the function use some kart properties and parachute
 *         effect needs to be applied, so keep both working if moving
 *  \param engine_power : the engine power on which to apply the decrease
 */
float Kart::applyAirFriction(float engine_power)
{
    //The physics already do that a certain amount of engine force is needed to keep going
    //at a given speed (~39,33 engine force = 1 speed for a mass of 350)
    //But it's either too slow to accelerate to a target speed or makes it
    //too easy to accelerate farther.
    //Instead of making increasing gears have enormous power gaps, apply friction

    float mass_factor = m_kart_properties->getMass()/350.0f;
    float compense_linear_slowdown = 39.33f*fabsf(getSpeed())*mass_factor;

    engine_power += compense_linear_slowdown;

    // The result will always be a positive number
    float friction_intensity = fabsf(getSpeed());

    // Not a pure quadratic evolution as it would be too brutal
    friction_intensity *= sqrt(friction_intensity)*5;

    // Apply parachute physics
    // Currently, all karts have the same base friction
    // If this is changed, a compensation needs to be added here
    if(m_attachment->getType()==Attachment::ATTACH_PARACHUTE)
        friction_intensity *= m_kart_properties->getParachuteFriction();

    if (friction_intensity < 0.0f) friction_intensity = 0.0f;

    // We subtract the friction from the engine power
    // 1)This is the logical behavior
    // 2)That way, engine boosts remain useful at high speed
    // 3)It helps heavier karts, who have an higher engine power

    engine_power-=friction_intensity;

    return engine_power;
} //applyAirFriction

//-----------------------------------------------------------------------------
/** Sets the engine power. It considers the engine specs, items that influence
 *  the available power, and braking/steering.
 */
void Kart::updateEnginePowerAndBrakes(int ticks)
{
    updateWeight();
    updateNitro(ticks);
    float engine_power = getActualWheelForce();

    // apply nitro boost if relevant
    if(getSpeedIncreaseTicksLeft(MaxSpeed::MS_INCREASE_NITRO) > 0)
    {
        engine_power*= m_kart_properties->getNitroEngineMult();
    }

    // apply bubblegum physics if relevant
    if (m_bubblegum_ticks > 0)
    {
        engine_power = 0.0f;
        m_body->applyTorque(btVector3(0.0,
            m_kart_properties->getBubblegumTorque() *
            (m_bubblegum_torque_sign ? 1.0f : -1.0f), 0.0));
    }

    if(m_controls.getAccel())   // accelerating
    {
        // For a short time after a collision disable the engine,
        // so that the karts can bounce back a bit from the obstacle.
        if (m_bounce_back_ticks > 0)
            engine_power = 0.0f;
        // let a player going backwards accelerate quickly (e.g. if a player
        // hits a wall, he needs to be able to start again quickly after
        // going backwards)
        else if(m_speed < 0.0f)
            engine_power *= 5.0f;

        // Lose some traction when skidding, to balance the advantage
        if (m_controls.getSkidControl() &&
            m_kart_properties->getSkidVisualTime() == 0)
            engine_power *= 0.5f;

        // This also applies parachute physics if relevant
        engine_power = applyAirFriction(engine_power);

        applyEngineForce(engine_power*m_controls.getAccel());

        // Either all or no brake is set, so test only one to avoid
        // resetting all brakes most of the time.
        if(m_vehicle->getWheelInfo(0).m_brake &&
            !World::getWorld()->isStartPhase())
            m_vehicle->setAllBrakes(0);
        m_brake_ticks = 0;
    }
    else // not accelerating
    {
        //The engine power is still guaranteed >= 0 at this point
        float braking_power = engine_power;

        // This also applies parachute physics if relevant
        engine_power = applyAirFriction(engine_power);
       
        if(m_controls.getBrake())
        {   // check if the player is currently only slowing down
            // or moving backwards
            if(m_speed > 0.0f)
            {   // Still going forward while braking
                applyEngineForce(engine_power-braking_power*3);
                m_brake_ticks += ticks;
                // Apply the brakes - include the time dependent brake increase
                float f = 1.0f + stk_config->ticks2Time(m_brake_ticks)
                               * m_kart_properties->getEngineBrakeTimeIncrease();
                m_vehicle->setAllBrakes(m_kart_properties->getEngineBrakeFactor() * f);
            }
            else   // m_speed < 0
            {
                m_vehicle->setAllBrakes(0);
                // going backward, apply reverse gear ratio (unless he goes
                // too fast backwards)
                if ( -m_speed <  m_max_speed->getCurrentMaxSpeed()
                                 *m_kart_properties->getEngineMaxSpeedReverseRatio())
                {
                    // The backwards acceleration is artificially increased to
                    // allow players to get "unstuck" quicker if they hit e.g.
                    // a wall.
                    applyEngineForce(engine_power-braking_power*3);
                }
                else  // -m_speed >= max speed on this terrain
                {
                    applyEngineForce(0.0f);
                }

            }   // m_speed <00
        }
        else   // no braking and no acceleration
        {
            m_brake_ticks = 0;
            // lift the foot from throttle, let friction slow it down
            assert(!std::isnan(m_controls.getAccel()));
            assert(!std::isnan(engine_power));

            // If not giving power (forward or reverse gear), and speed is low
            // we are "parking" the kart, so in battle mode we can ambush people
            if (std::abs(m_speed) < 5.0f)
            {
                // Engine must be 0, otherwise braking is not used at all
                applyEngineForce(0);
                m_vehicle->setAllBrakes(20.0f);
            }
            else
            {
                // This ensure that parachute and air friction are applied
                // and that the kart gracefully slows down
                applyEngineForce(engine_power-braking_power);
                m_vehicle->setAllBrakes(0);
            }
        }   // no braking and no acceleration
    }   // not accelerating
}   // updateEnginePowerAndBrakes

// ----------------------------------------------------------------------------
/** Handles sliding, i.e. the kart sliding off terrain that is too steep.
 *  Dynamically determine friction so that the kart looses its traction
 *  when trying to drive on too steep surfaces. Below angles of 0.25 rad,
 *  you have full traction; above 0.5 rad angles you have absolutely none;
 *  inbetween  there is a linear change in friction. This is done for each
 *  wheel individually (since otherwise karts were still able with enough
 *  speed to drive on walls - one wheel 'on a wall' would not tilt the
 *  kart chassis enough to trigger sliding, but since that wheel had still
 *  full friction, give the kart an upwards velocity).
 */
void Kart::updateSliding()
{
    // Allow the sliding to be disabled per material (for so called
    // high adhesion material), which is useful for e.g. banked curves.
    // We don't have per-wheel material, so the test for special material
    // with high adhesion is done per kart (not per wheel).
    const Material * material = getMaterial();
    if (material && material->highTireAdhesion())
    {
        for (int i = 0; i < m_vehicle->getNumWheels(); i++)
        {
            btWheelInfo &wheel = m_vehicle->getWheelInfo(i);
            wheel.m_frictionSlip = m_kart_properties->getFrictionSlip();
        }
        m_vehicle->setSliding(false);

    }

    // Now test for each wheel if it should be sliding
    // -----------------------------------------------
    bool enable_sliding = false;

    // We need the 'up' vector, which can be affected by material
    // with gravity. So use the body's gravity to determine up:
    Vec3 up = -m_body->getGravity();
    up.normalize();
    for (int i = 0; i < m_vehicle->getNumWheels(); i++)
    {
        const btWheelInfo &wheel = m_vehicle->getWheelInfo(i);
        if (!wheel.m_raycastInfo.m_isInContact) continue;

        const btVector3 &norm = m_vehicle->getWheelInfo(i).m_raycastInfo.m_contactNormalWS;
        float distanceFromUp = norm.dot(up);
        float friction;
        if (distanceFromUp < 0.85f)
        {
            friction = 0.0f;
            enable_sliding = true;
        }
        else if (distanceFromUp > 0.9f)
        {
            friction = 1.0f;
        }
        else
        {
            friction = (distanceFromUp - 0.85f) / 0.5f;
            enable_sliding = true;
        }
        m_vehicle->getWheelInfo(i).m_frictionSlip = friction * m_kart_properties->getFrictionSlip();
    }   // for i < numWheels

    m_vehicle->setSliding(enable_sliding);
}   // updateSliding

// ----------------------------------------------------------------------------
/** Adjusts kart translation if the kart is flying (in debug mode).
 */
void Kart::updateFlying()
{
    m_body->setLinearVelocity(m_body->getLinearVelocity() * 0.99f);

    if (m_controls.getAccel())
    {
        btVector3 velocity = m_body->getLinearVelocity();
        if (velocity.length() < 25)
        {
            float orientation = getHeading();
            m_body->applyCentralImpulse(btVector3(100.0f*sinf(orientation), 0.0,
                100.0f*cosf(orientation)));
        }
    }
    else if (m_controls.getBrake())
    {
        btVector3 velocity = m_body->getLinearVelocity();
        if (velocity.length() > -15)
        {
            float orientation = getHeading();
            m_body->applyCentralImpulse(btVector3(-100.0f*sinf(orientation), 0.0,
                -100.0f*cosf(orientation)));
        }
    }

    if (m_controls.getSteer()!= 0.0f)
    {
        m_body->applyTorque(btVector3(0.0, m_controls.getSteer()*3500.0f, 0.0));
    }

    // dampen any roll while flying, makes the kart hard to control
    btVector3 velocity = m_body->getAngularVelocity();
    velocity.setX(0);
    velocity.setZ(0);
    m_body->setAngularVelocity(velocity);

}   // updateFlying

// ----------------------------------------------------------------------------
/** Attaches the right model, creates the physics and loads all special
 *  effects (particle systems etc.)
 *  \param type Type of the kart.
 *  \param is_animated_model True if the model is animated.
 */
void Kart::loadData(RaceManager::KartType type, bool is_animated_model)
{
    bool always_animated = (type == RaceManager::KT_PLAYER &&
        RaceManager::get()->getNumLocalPlayers() == 1);
    if (!GUIEngine::isNoGraphics())
        m_node = m_kart_model->attachModel(is_animated_model, always_animated);

#ifdef DEBUG
    if (m_node)
        m_node->setName( (getIdent()+"(lod-node)").c_str() );
#endif

    // Attachment must be created after attachModel, since only then the
    // scene node will exist (to which the attachment is added). But the
    // attachment is needed in createPhysics (which gets the mass, which
    // is dependent on the attachment).
    m_attachment.reset(new Attachment(this));
    createPhysics();

    m_slipstream.reset(new SlipStream(this));

#ifndef SERVER_ONLY
    m_skidmarks = nullptr;
    m_shadow = nullptr;
    if (!GUIEngine::isNoGraphics() &&
        m_kart_properties->getSkidEnabled())
    {
        m_skidmarks.reset(new SkidMarks(*this));
    }

    if (!GUIEngine::isNoGraphics() &&
        (!CVS->isGLSL() || !CVS->isShadowEnabled()) && m_kart_properties
        ->getShadowMaterial()->getSamplerPath(0) != "unicolor_white")
    {
        m_shadow.reset(new Shadow(m_kart_properties->getShadowMaterial(),
            *this));
    }
#endif
    World::getWorld()->kartAdded(this, m_node);
    m_kart_gfx.reset(
        new KartGFX(this, Track::getCurrentTrack()->getIsDuringDay()));
    m_skidding.reset(new Skidding(this));
    // Create the stars effect
    if (!GUIEngine::isNoGraphics())
        m_stars_effect.reset(new Stars(this));

    // Clear previous sound if exists when changeKart
    if (m_engine_sound)
        m_engine_sound->deleteSFX();
    m_engine_sound = SFXManager::get()->createSoundSource(m_kart_properties->getEngineSfxType());
    if (!m_engine_sound)
        Log::error("Kart","Could not allocate a sfx object for the kart. Further errors may ensue!");

    if (m_skid_sound)
    {
        m_skid_sound->deleteSFX();
        m_skid_sound = NULL;
    }
    if (!m_kart_properties->getSkidSound().empty())
    {
        m_skid_sound = SFXManager::get()->createSoundSource(
            m_kart_properties->getSkidSound());
    }
}   // loadData

// ----------------------------------------------------------------------------
/** Applies engine power to all the wheels that are traction capable,
 *  so other parts of code do not have to be adjusted to simulate different
 *  kinds of vehicles in the general case, only if they are trying to
 *  simulate traction control, diferentials or multiple independent electric
 *  engines, they will have to tweak the power in a per wheel basis.
 */
void Kart::applyEngineForce(float force)
{
    assert(!std::isnan(force));
    // Split power to simulate a 4WD 40-60, other values possible
    // FWD or RWD is a matter of putting a 0 and 1 in the right place
    float frontForce = force*0.4f;
    float rearForce = force*0.6f;
    // Front wheels
    for(unsigned int i=0; i<2; i++)
    {
        m_vehicle->applyEngineForce (frontForce, i);
    }
    // Rear wheels
    for(unsigned int i=2; i<4; i++)
    {
        m_vehicle->applyEngineForce (rearForce, i);
    }
}   // applyEngineForce

//-----------------------------------------------------------------------------
/** Computes the transform of the graphical kart chasses with regards to the
 *  physical chassis. This function is called once the kart comes to rest
 *  before the race starts (see World::resetAllKarts). Based on the current
 *  physical kart position it computes an (at this stage Y-only) offset by
 *  which the graphical chassis is moved so that it appears the way it is
 *  designed in blender. This means that the distance of the wheels from the
 *  chassis (i.e. suspension) appears as in blender when karts are in rest.
 *  See updateGraphics for more details.
 */
void Kart::kartIsInRestNow()
{
    AbstractKart::kartIsInRestNow();
    m_default_suspension_force = 0.0f;
    for (int i = 0; i < m_vehicle->getNumWheels(); i++)
    {
        const btWheelInfo &wi = m_vehicle->getWheelInfo(i);
        m_default_suspension_force += wi.m_raycastInfo.m_suspensionLength;
    }

    // The offset 'lowest point' is added to avoid that the
    // visual chassis appears in the ground (it could be any
    // constant, there is no real reason to use the lowest point
    // but that value has worked good in the past). See documentation
    // for updateGraphics() for full details.
    m_graphical_y_offset = -m_default_suspension_force /
        m_vehicle->getNumWheels() + m_kart_model->getLowestPoint();

    m_kart_model->setDefaultSuspension();
}   // kartIsInRestNow

//-----------------------------------------------------------------------------

SFXBase* Kart::getNextEmitter()
{
    m_emitter_id = (m_emitter_id + 1) % EMITTER_COUNT;

    // The emitter is requested when a new sound is to be played.
    // Always reset the volume to 1.0f (full), as crashes may
    // have altered it. See issue #3596
    m_emitters[m_emitter_id]->setVolume(1.0f);

    return m_emitters[m_emitter_id];
}

//-----------------------------------------------------------------------------
/** Updates the graphics model. It is responsible for positioning the graphical
 *  chasses at an 'appropriate' position: typically, the physical model has
 *  much longer suspension, so if the graphical chassis would be at the same
 *  location as the physical chassis, the wheels would be too far away.
 *  Instead the default suspension length is saved once the kart have been
 *  settled at start up (see World::resetAllKarts, which just runs several
 *  physics-only simulation steps so that karts come to a rest). Then at
 *  race time, only the difference between the current suspension length and
 *  this default suspension length is used. The graphical kart chassis will be
 *  offset so that when the kart is in rest, i.e. suspension length ==
 *  default suspension length, the kart will look the way it was modelled in
 *  blender. To explain the various offsets used, here a view from the side
 *  focusing on the Y axis only (X/Z position of the graphical chassis is
 *  identical to the physical chassis):
 *
 * Y|     | visual kart                |       physical kart
 *  |     |                            |
 *  |     |                            |
 *  |     |                            |
 *  |     |                            +-------------COG---------------
 *  |     |                            :
 *  |     +---------low------          :
 *  |     O                            :
 *  +--------------------------------------------------------------------------
 *                                                                            X
 *  'O'   : visual wheel                ':'  : raycast from physics
 *  'low' : lowest Y coordinate of      COG  : Center of gravity (at bottom of
 *          model                              chassis)
 *
 *  The visual kart is stored so that if it is shown at (0,0,0) it would be
 *  the same as in blender. This on the other hand means, if the kart is shown
 *  at the position of the physical chassis (which is at COG in the picture
 *  above), the kart and its wheels would be floating in the air (exactly by
 *  as much as the suspension length), and the wheels would be exactly at the
 *  bottom of the physical chassis (i.e. just on the plane going through COG
 *  and parallel to the ground).
 *  If we want to align the visual chassis to be the same as the physical
 *  chassis, we would need to subtract 'low' from the physical position.
 *  If the kart is then displayed at COG.y-low, the bottom of the kart (which
 *  is at 'low' above ground) would be at COG.y-low + low = COG.y --> visual
 *  and physical chassis are identical.
 *
 *  Unfortunately, the suspension length used in the physics is much too high,
 *  the karts would be way above their wheels, basically disconneccted
 *  (typical physical suspension length is around 0.28, while the distance
 *  between wheel and chassis in blender is in the order of 0.10 --> so there
 *  would be an additional distance of around 0.18 between wheel chassis as
 *  designed in blender and in stk - even more if the kart is driving downhill
 *  when the suspension extends further to keep contact with the ground).
 *  To make the visuals look closer to what they are in blender, an additional
 *  offset is added: before the start of a race the physics simulation is run
 *  to find a stable position for each kart (see World::resetAllKarts). Once
 *  a kart is stable, we save this suspension length in m_graphical_y_offset.
 *  This offset is subtracted from the COG of the kart. So if the kart is in
 *  rest (i.e. suspenion == default_suspension == m_graphical_y_offset),
 *  The kart is showen exactly at the same height above ground as it is in
 *  blender. If the suspension is shorter by DY (because the kart is
 *  accelerating, the ground goes up, ...), the visual chassis is lowered by
 *  DY as well.
 *
 *  While the above algorithm indeed results in the right position of the
 *  visual chassis, in reality the visual chassis is too low. For example,
 *  nolok's chassis has its lowest point at the rear at around 0.10 above the
 *  ground (and the lowest point overall is 0.05, though this is at the front
 *  and so not easily visible), so if the suspension is compressed by more than
 *  that, the chassiswill appear to be in the ground. Testing on the sand track
 *  shows that the suspension is compressed by 0.12 (and up to 0.16 in some
 *  extreme points), which means that the chassis will appear to be in the
 *  ground quite easily. Therefore the chassis is actually moved up a bit to
 *  avoid this problem. Historically (due to never sorting out that formula
 *  properly) the chassis was moved twice as high as its lowest point, e.g.
 *  nolok's lowest point is at 0.05, so the whole chassis was raised by 0.05
 *  (this was not done by design, but because of a bug ;)  ). Since this visual
 *  offset has worked well in the past, the visual chassis is moved by the
 *  same amount higher.
 *
 *  Of course this means that the Y position of the wheels (relative to the
 *  visual kart chassis) needs to be adjusted: if the kart is in rest, the
 *  wheels are exactly on the ground. If the suspension is shorter, that wheel
 *  would appear to be partly in the ground, and if the suspension is longer,
 *  the wheel would not touch the ground.
 *
 *  The wheels must be offset by how much the current suspension length is
 *  longer or shorter than the default (i.e. at rest) suspension length.
 *  This is done in KartModel (pos is the position of the wheel relative
 *  to the visual kart chassis):
 *          pos.Y += m_default_physics_suspension[i]
 *                  - wi.m_raycastInfo.m_suspensionLength
 *  But since the chassis is raised an additional 'getLowestPoint' (see
 *  desctiption two paragraphs above), the wheels need to be lowered by that
 *  amount so that they still touch the ground (the wheel nodes are child of
 *  the chassis scene node, so if the chassis is raised by X, the wheels need
 *  to be lowered by X).
 *  This function also takes additional graphical effects into account, e.g.
 *  a (visual only) jump when skidding, and leaning of the kart.
 */
void Kart::updateGraphics(float dt)
{
    /* (TODO: add back when properly done)
    for (int n = 0; n < SFXManager::NUM_CUSTOMS; n++)
    {
        if (m_custom_sounds[n] != NULL) m_custom_sounds[n]->position(getXYZ());
    }
     */
#ifndef SERVER_ONLY
    if (m_node && isSquashed() &&
        m_node->getScale() != core::vector3df(1.0f, 0.5f, 1.0f))
        setSquashGraphics();
    else if (m_node && !isSquashed() &&
        m_node->getScale() != core::vector3df(1.0f, 1.0f, 1.0f))
        unsetSquash();
#endif

    // Disable smoothing network body so it doesn't smooth the animation
    // for karts in client
    if (NetworkConfig::get()->isNetworking() &&
        NetworkConfig::get()->isClient() &&
        (!getController() || !getController()->isLocalPlayerController()))
    {
        if (m_kart_animation && SmoothNetworkBody::isEnabled())
        {
            SmoothNetworkBody::setEnable(false);
        }
        else if (!m_kart_animation && !SmoothNetworkBody::isEnabled())
        {
            SmoothNetworkBody::setEnable(true);
            SmoothNetworkBody::reset();
            SmoothNetworkBody::setSmoothedTransform(getTrans());
        }
    }

    if (m_kart_animation)
        m_kart_animation->updateGraphics(dt);

    for (int i = 0; i < EMITTER_COUNT; i++)
        m_emitters[i]->setPosition(getXYZ());

    m_attachment->updateGraphics(dt);

    // update star effect (call will do nothing if stars are not activated)
    // Remove it if no invulnerability
    if (m_stars_effect)
    {
        if (!isInvulnerable() && m_stars_effect->isEnabled())
        {
            m_stars_effect->reset();
            m_stars_effect->update(1);
        }
        else
            m_stars_effect->update(dt);
    }

    // Update particle effects (creation rate, and emitter size
    // depending on speed)
    m_kart_gfx->update(dt);

#ifndef SERVER_ONLY
    if (m_collision_particles) m_collision_particles->update(dt);
#endif

    // --------------------------------------------------------
    float nitro_frac = 0;
    if ( (m_controls.getNitro() || m_min_nitro_ticks > 0) &&
         m_collected_energy > 0                               )
    {
        // fabs(speed) is important, otherwise the negative number will
        // become a huge unsigned number in the particle scene node!
        nitro_frac = fabsf(getSpeed()) / (m_kart_properties->getEngineMaxSpeed());
        // The speed of the kart can be higher (due to powerups) than
        // the normal maximum speed of the kart.
        if(nitro_frac>1.0f) nitro_frac = 1.0f;
    }
    m_kart_gfx->updateNitroGraphics(nitro_frac);

    // Handle leaning of karts
    // -----------------------
    // Note that we compare with maximum speed of the kart, not
    // maximum speed including terrain effects. This avoids that
    // leaning might get less if a kart gets a special that increases
    // its maximum speed, but not the current speed (by much). On the
    // other hand, that ratio can often be greater than 1.

    float speed_frac = m_speed / m_kart_properties->getEngineMaxSpeed();
    float steer_frac = m_skidding->getSteeringFraction();
    const float roll_speed = m_kart_properties->getLeanSpeed() * DEGREE_TO_RAD;

    if(speed_frac > 0.8f && fabsf(steer_frac)>0.2f)
    {
        // Use steering and speed ^ 2,
        // which means less effect at lower steering and speed.
        speed_frac = std::min(speed_frac - 0.6f, 1.0f);
        steer_frac = (steer_frac+0.25f)*0.8f;
        const float f = m_skidding->getSteeringFraction();
        const float max_lean = -m_kart_properties->getLeanMax() * DEGREE_TO_RAD
                             * f * speed_frac * speed_frac;

        int max_lean_sign = extract_sign(max_lean);
        m_current_lean += max_lean_sign * dt* roll_speed;
        if(  (max_lean > 0 && m_current_lean > max_lean)
           ||(max_lean < 0 && m_current_lean < max_lean)) 
            m_current_lean = max_lean;
    }
    else if(m_current_lean!=0.0f)
    {
        // Disable any potential roll factor that is still applied
        int lean_sign = extract_sign(m_current_lean);
        m_current_lean -= lean_sign * dt * roll_speed;
        if (lean_sign != extract_sign(m_current_lean))
            m_current_lean = 0.0f;
    }

    // If the kart is leaning, part of the kart might end up 'in' the track.
    // To avoid this, raise the kart enough to offset the leaning.
    float lean_height = tanf(m_current_lean) * getKartWidth()*0.5f;

    Moveable::updateSmoothedGraphics(dt);

    // Update the skidding jump height:
    Vec3 center_shift(0, 0, 0);
    float jump_height = m_skidding->updateGraphics(dt);
    center_shift.setY(jump_height + fabsf(lean_height) + m_graphical_y_offset);
    center_shift = getSmoothedTrans().getBasis() * center_shift;

    float heading = m_skidding->getVisualSkidRotation();
    Moveable::updateGraphics(center_shift,
        btQuaternion(heading, 0, -m_current_lean));

    static video::SColor pink(255, 255, 133, 253);
    static video::SColor green(255, 61, 87, 23);

#ifndef SERVER_ONLY
    // draw skidmarks if relevant (we force pink skidmarks on when hitting
    // a bubblegum)
    if (World::getWorld()->getPhase() !=
        WorldStatus::IN_GAME_MENU_PHASE &&
        m_kart_properties->getSkidEnabled() && m_skidmarks)
    {
        m_skidmarks->update(dt,
            m_bubblegum_ticks > 0,
            (m_bubblegum_ticks > 0
                ? (m_has_caught_nolok_bubblegum ? &green
                    : &pink)
                : NULL));
    }
#endif

    // m_speed * dt is the distance the kart has moved, which determines
    // how much the wheels need to rotate.
    m_kart_model->update(dt, m_speed * dt, getSteerPercent(), m_speed,
        m_current_lean);

#ifndef SERVER_ONLY
    // Determine the shadow position from the terrain Y position. This
    // leaves the shadow on the ground even if the kart is jumping because
    // of skidding (shadows are disabled when wheel are not on the track).
    if (m_shadow)
    {
        const bool emergency = getKartAnimation() != NULL;
        m_shadow->update(isOnGround() && !emergency);
    }
#endif

    handleMaterialGFX(dt);
    updateEngineSFX(dt);
    handleMaterialSFX();
}   // updateGraphics

// ----------------------------------------------------------------------------
btQuaternion Kart::getVisualRotation() const
{
    return getRotation()
         * btQuaternion(m_skidding->getVisualSkidRotation(), 0, 0);
}   // getVisualRotation

// ----------------------------------------------------------------------------
/** Sets a text that is being displayed on top of a kart. This can be 'leader'
 *  for the leader kart in a FTL race, the name of a driver, or even debug
 *  output.
 *  \param text The text to display
 */
void Kart::setOnScreenText(const core::stringw& text)
{
#ifndef SERVER_ONLY
    if (GUIEngine::isNoGraphics())
        return;
        
    BoldFace* bold_face = font_manager->getFont<BoldFace>();
    STKTextBillboard* tb =
        new STKTextBillboard(
        GUIEngine::getSkin()->getColor("font::bottom"),
        GUIEngine::getSkin()->getColor("font::top"),
        getNode(), irr_driver->getSceneManager(), -1,
        core::vector3df(0.0f, 1.5f, 0.0f),
        core::vector3df(0.5f, 0.5f, 0.5f));
    if (CVS->isGLSL())
        tb->init(text, bold_face);
    else
        tb->initLegacy(text, bold_face);
    tb->drop();
    // No need to store the reference to the billboard scene node:
    // It has one reference to the parent, and will get deleted
    // when the parent is deleted.
#endif
}   // setOnScreenText

// ------------------------------------------------------------------------
/** Returns the normal of the terrain the kart is over atm. This is
  * defined even if the kart is flying. */
const Vec3& Kart::getNormal() const
{
    return m_terrain_info->getNormal();
} // getNormal

// ------------------------------------------------------------------------
/** Returns a more recent different previous position */
const Vec3& Kart::getRecentPreviousXYZ() const
{
    //Not the most recent, because the angle variations would be too
    //irregular on some tracks whose roads are not smooth enough
    return m_previous_xyz[m_xyz_history_size/5];
}   // getRecentPreviousXYZ

// ------------------------------------------------------------------------
void Kart::playSound(SFXBuffer* buffer)
{
    if (!RewindManager::get()->isRewinding())
        getNextEmitter()->play(getSmoothedXYZ(), buffer);
}   // playSound

// ------------------------------------------------------------------------
const video::SColor& Kart::getColor() const
{
    return m_kart_properties->getColor();
} // getColor

// ------------------------------------------------------------------------
bool Kart::isVisible() const
{
    return m_node && m_node->isVisible();
} // isVisible

/* EOF */
