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- // SuperTux
- // Copyright (C) 2006 Matthias Braun <matze@braunis.de>
- // Copyright (C) 2024 bruhmoent
- //
- // 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, see <http://www.gnu.org/licenses/>.
- #include "object/snow_particle_system.hpp"
- #include <assert.h>
- #include <math.h>
- #include "math/random.hpp"
- #include "supertux/sector.hpp"
- #include "util/reader_mapping.hpp"
- #include "video/surface.hpp"
- #include "video/video_system.hpp"
- #include "video/viewport.hpp"
-
- static const float DECAY_RATIO = 0.2f; // Ratio of attack speed to decay speed.
- static const float WOBBLE_DECAY = 0.99f; // Wobble decays exponentially by this much each tick.
- static const float WOBBLE_FACTOR = 4 * .005f; // Wobble approaches drift_speed by this much each tick.
- SnowParticleSystem::SnowParticleSystem() :
- m_state(RELEASING),
- m_timer(),
- m_gust_onset(0),
- m_gust_current_velocity(0)
- {
- init();
- }
- SnowParticleSystem::SnowParticleSystem(const ReaderMapping& reader) :
- ParticleSystem(reader),
- m_state(RELEASING),
- m_timer(),
- m_gust_onset(0),
- m_gust_current_velocity(0)
- {
- reader.get("state_length", m_state_length, 5.0f);
- reader.get("wind_speed", m_wind_speed, 30.0f);
- reader.get("spin_speed", m_spin_speed, 60.0f);
- reader.get("epsilon", m_epsilon, 0.5f);
- init();
- }
- SnowParticleSystem::~SnowParticleSystem()
- {
- }
- void
- SnowParticleSystem::init()
- {
- m_snowimages[0] = Surface::from_file("images/particles/snow2.png");
- m_snowimages[1] = Surface::from_file("images/particles/snow1.png");
- m_snowimages[2] = Surface::from_file("images/particles/snow0.png");
- virtual_width = static_cast<float>(SCREEN_WIDTH) * 2.0f;
- m_timer.start(.01f);
- // Create random snowflakes.
- int snowflakecount = static_cast<int>(virtual_width / 10.0f);
- for (int i = 0; i < snowflakecount; ++i)
- {
- auto particle = std::make_unique<SnowParticle>();
- int snowsize = graphicsRandom.rand(3);
- particle->pos.x = graphicsRandom.randf(virtual_width);
- particle->pos.y = graphicsRandom.randf(static_cast<float>(SCREEN_HEIGHT));
- particle->anchorx = particle->pos.x + (graphicsRandom.randf(-0.5, 0.5) * 16);
- // Drift will change with wind gusts.
- particle->drift_speed = graphicsRandom.randf(-0.5f, 0.5f) * 0.3f;
- particle->wobble = 0.0;
- particle->texture = m_snowimages[snowsize];
- particle->flake_size = static_cast<int>(powf(static_cast<float>(snowsize) + 3.0f, 4.0f)); // Since it ranges from 0 to 2.
- particle->speed = 6.32f * (1.0f + (2.0f - static_cast<float>(snowsize)) / 2.0f + graphicsRandom.randf(1.8f));
- // Spinning.
- particle->angle = graphicsRandom.randf(360.0);
- particle->spin_speed = graphicsRandom.randf(-m_spin_speed, m_spin_speed);
- particles.push_back(std::move(particle));
- }
- }
- ObjectSettings
- SnowParticleSystem::get_settings()
- {
- ObjectSettings result = ParticleSystem::get_settings();
- result.add_float(_("Epsilon"), &m_epsilon, "epsilon", 0.5f);
- result.add_float(_("Spin Speed"), &m_spin_speed, "spin_speed", 60.0f);
- result.add_float(_("State Length"), &m_state_length, "state_length", 5.0f);
- result.add_float(_("Wind Speed"), &m_wind_speed, "wind_speed", 30.0f);
- result.reorder({ "epsilon", "spin_speed", "state_length", "wind_speed", "enabled", "name" });
- return result;
- }
- void
- SnowParticleSystem::update(float dt_sec)
- {
- if (!enabled)
- return;
-
- // Simple ADSR wind gusts.
- if (m_timer.check())
- {
- // Change state
- m_state = static_cast<State>((m_state + 1) % MAX_STATE);
- if (m_state == RESTING)
- {
- // Stop wind.
- m_gust_current_velocity = 0;
- // New wind strength.
- m_gust_onset = -m_wind_speed;
- }
- m_timer.start(graphicsRandom.randf(m_state_length));
- }
- // Update velocities.
- switch (m_state)
- {
- case ATTACKING:
- m_gust_current_velocity += m_gust_onset * dt_sec;
- break;
- case DECAYING:
- m_gust_current_velocity -= m_gust_onset * dt_sec * DECAY_RATIO;
- break;
- case RELEASING:
- // Uses current time/velocity instead of constants.
- m_gust_current_velocity -= m_gust_current_velocity * dt_sec / m_timer.get_timeleft();
- break;
- case SUSTAINING:
- case RESTING:
- break;
- default:
- assert(false);
- }
- float sq_g = sqrtf(Sector::get().get_gravity());
- for (auto& part : particles)
- {
- auto particle = dynamic_cast<SnowParticle*>(part.get());
- if (!particle)
- continue;
- float anchor_delta;
- // Falling.
- particle->pos.y += particle->speed * dt_sec * sq_g;
- // Drifting (speed approaches wind at a rate dependent on flake size).
- particle->drift_speed += (m_gust_current_velocity - particle->drift_speed) / static_cast<float>(particle->flake_size) + graphicsRandom.randf(-m_epsilon, m_epsilon);
- particle->anchorx += particle->drift_speed * dt_sec;
- // Wobbling (particle approaches anchorx).
- particle->pos.x += particle->wobble * dt_sec * sq_g;
- anchor_delta = (particle->anchorx - particle->pos.x);
- particle->wobble += (WOBBLE_FACTOR * anchor_delta) + graphicsRandom.randf(-m_epsilon, m_epsilon);
- particle->wobble *= WOBBLE_DECAY;
- // Spinning.
- particle->angle += particle->spin_speed * dt_sec;
- particle->angle = fmodf(particle->angle, 360.0);
- }
- }
- /* EOF */
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