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- /*
- Written by Xuchen Han <xuchenhan2015@u.northwestern.edu>
-
- Bullet Continuous Collision Detection and Physics Library
- Copyright (c) 2019 Google Inc. http://bulletphysics.org
- This software is provided 'as-is', without any express or implied warranty.
- In no event will the authors be held liable for any damages arising from the use of this software.
- Permission is granted to anyone to use this software for any purpose,
- including commercial applications, and to alter it and redistribute it freely,
- subject to the following restrictions:
- 1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
- 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
- 3. This notice may not be removed or altered from any source distribution.
- */
- #include "btDeformableBackwardEulerObjective.h"
- #include "btPreconditioner.h"
- #include "LinearMath/btQuickprof.h"
- btDeformableBackwardEulerObjective::btDeformableBackwardEulerObjective(btAlignedObjectArray<btSoftBody*>& softBodies, const TVStack& backup_v)
- : m_softBodies(softBodies), m_projection(softBodies), m_backupVelocity(backup_v), m_implicit(false)
- {
- m_massPreconditioner = new MassPreconditioner(m_softBodies);
- m_KKTPreconditioner = new KKTPreconditioner(m_softBodies, m_projection, m_lf, m_dt, m_implicit);
- m_preconditioner = m_KKTPreconditioner;
- }
- btDeformableBackwardEulerObjective::~btDeformableBackwardEulerObjective()
- {
- delete m_KKTPreconditioner;
- delete m_massPreconditioner;
- }
- void btDeformableBackwardEulerObjective::reinitialize(bool nodeUpdated, btScalar dt)
- {
- BT_PROFILE("reinitialize");
- if (dt > 0)
- {
- setDt(dt);
- }
- if (nodeUpdated)
- {
- updateId();
- }
- for (int i = 0; i < m_lf.size(); ++i)
- {
- m_lf[i]->reinitialize(nodeUpdated);
- }
- btMatrix3x3 I;
- I.setIdentity();
- for (int i = 0; i < m_softBodies.size(); ++i)
- {
- btSoftBody* psb = m_softBodies[i];
- for (int j = 0; j < psb->m_nodes.size(); ++j)
- {
- if (psb->m_nodes[j].m_im > 0)
- psb->m_nodes[j].m_effectiveMass = I * (1.0 / psb->m_nodes[j].m_im);
- }
- }
- m_projection.reinitialize(nodeUpdated);
- // m_preconditioner->reinitialize(nodeUpdated);
- }
- void btDeformableBackwardEulerObjective::setDt(btScalar dt)
- {
- m_dt = dt;
- }
- void btDeformableBackwardEulerObjective::multiply(const TVStack& x, TVStack& b) const
- {
- BT_PROFILE("multiply");
- // add in the mass term
- size_t counter = 0;
- for (int i = 0; i < m_softBodies.size(); ++i)
- {
- btSoftBody* psb = m_softBodies[i];
- for (int j = 0; j < psb->m_nodes.size(); ++j)
- {
- const btSoftBody::Node& node = psb->m_nodes[j];
- b[counter] = (node.m_im == 0) ? btVector3(0, 0, 0) : x[counter] / node.m_im;
- ++counter;
- }
- }
- for (int i = 0; i < m_lf.size(); ++i)
- {
- // add damping matrix
- m_lf[i]->addScaledDampingForceDifferential(-m_dt, x, b);
- // Always integrate picking force implicitly for stability.
- if (m_implicit || m_lf[i]->getForceType() == BT_MOUSE_PICKING_FORCE)
- {
- m_lf[i]->addScaledElasticForceDifferential(-m_dt * m_dt, x, b);
- }
- }
- int offset = m_nodes.size();
- for (int i = offset; i < b.size(); ++i)
- {
- b[i].setZero();
- }
- // add in the lagrange multiplier terms
- for (int c = 0; c < m_projection.m_lagrangeMultipliers.size(); ++c)
- {
- // C^T * lambda
- const LagrangeMultiplier& lm = m_projection.m_lagrangeMultipliers[c];
- for (int i = 0; i < lm.m_num_nodes; ++i)
- {
- for (int j = 0; j < lm.m_num_constraints; ++j)
- {
- b[lm.m_indices[i]] += x[offset + c][j] * lm.m_weights[i] * lm.m_dirs[j];
- }
- }
- // C * x
- for (int d = 0; d < lm.m_num_constraints; ++d)
- {
- for (int i = 0; i < lm.m_num_nodes; ++i)
- {
- b[offset + c][d] += lm.m_weights[i] * x[lm.m_indices[i]].dot(lm.m_dirs[d]);
- }
- }
- }
- }
- void btDeformableBackwardEulerObjective::updateVelocity(const TVStack& dv)
- {
- for (int i = 0; i < m_softBodies.size(); ++i)
- {
- btSoftBody* psb = m_softBodies[i];
- for (int j = 0; j < psb->m_nodes.size(); ++j)
- {
- btSoftBody::Node& node = psb->m_nodes[j];
- node.m_v = m_backupVelocity[node.index] + dv[node.index];
- }
- }
- }
- void btDeformableBackwardEulerObjective::applyForce(TVStack& force, bool setZero)
- {
- size_t counter = 0;
- for (int i = 0; i < m_softBodies.size(); ++i)
- {
- btSoftBody* psb = m_softBodies[i];
- if (!psb->isActive())
- {
- counter += psb->m_nodes.size();
- continue;
- }
- if (m_implicit)
- {
- for (int j = 0; j < psb->m_nodes.size(); ++j)
- {
- if (psb->m_nodes[j].m_im != 0)
- {
- psb->m_nodes[j].m_v += psb->m_nodes[j].m_effectiveMass_inv * force[counter++];
- }
- }
- }
- else
- {
- for (int j = 0; j < psb->m_nodes.size(); ++j)
- {
- btScalar one_over_mass = (psb->m_nodes[j].m_im == 0) ? 0 : psb->m_nodes[j].m_im;
- psb->m_nodes[j].m_v += one_over_mass * force[counter++];
- }
- }
- }
- if (setZero)
- {
- for (int i = 0; i < force.size(); ++i)
- force[i].setZero();
- }
- }
- void btDeformableBackwardEulerObjective::computeResidual(btScalar dt, TVStack& residual)
- {
- BT_PROFILE("computeResidual");
- // add implicit force
- for (int i = 0; i < m_lf.size(); ++i)
- {
- // Always integrate picking force implicitly for stability.
- if (m_implicit || m_lf[i]->getForceType() == BT_MOUSE_PICKING_FORCE)
- {
- m_lf[i]->addScaledForces(dt, residual);
- }
- else
- {
- m_lf[i]->addScaledDampingForce(dt, residual);
- }
- }
- // m_projection.project(residual);
- }
- btScalar btDeformableBackwardEulerObjective::computeNorm(const TVStack& residual) const
- {
- btScalar mag = 0;
- for (int i = 0; i < residual.size(); ++i)
- {
- mag += residual[i].length2();
- }
- return std::sqrt(mag);
- }
- btScalar btDeformableBackwardEulerObjective::totalEnergy(btScalar dt)
- {
- btScalar e = 0;
- for (int i = 0; i < m_lf.size(); ++i)
- {
- e += m_lf[i]->totalEnergy(dt);
- }
- return e;
- }
- void btDeformableBackwardEulerObjective::applyExplicitForce(TVStack& force)
- {
- for (int i = 0; i < m_softBodies.size(); ++i)
- {
- m_softBodies[i]->advanceDeformation();
- }
- if (m_implicit)
- {
- // apply forces except gravity force
- btVector3 gravity;
- for (int i = 0; i < m_lf.size(); ++i)
- {
- if (m_lf[i]->getForceType() == BT_GRAVITY_FORCE)
- {
- gravity = static_cast<btDeformableGravityForce*>(m_lf[i])->m_gravity;
- }
- else
- {
- m_lf[i]->addScaledForces(m_dt, force);
- }
- }
- for (int i = 0; i < m_lf.size(); ++i)
- {
- m_lf[i]->addScaledHessian(m_dt);
- }
- for (int i = 0; i < m_softBodies.size(); ++i)
- {
- btSoftBody* psb = m_softBodies[i];
- if (psb->isActive())
- {
- for (int j = 0; j < psb->m_nodes.size(); ++j)
- {
- // add gravity explicitly
- psb->m_nodes[j].m_v += m_dt * psb->m_gravityFactor * gravity;
- }
- }
- }
- }
- else
- {
- for (int i = 0; i < m_lf.size(); ++i)
- {
- m_lf[i]->addScaledExplicitForce(m_dt, force);
- }
- }
- // calculate inverse mass matrix for all nodes
- for (int i = 0; i < m_softBodies.size(); ++i)
- {
- btSoftBody* psb = m_softBodies[i];
- if (psb->isActive())
- {
- for (int j = 0; j < psb->m_nodes.size(); ++j)
- {
- if (psb->m_nodes[j].m_im > 0)
- {
- psb->m_nodes[j].m_effectiveMass_inv = psb->m_nodes[j].m_effectiveMass.inverse();
- }
- }
- }
- }
- applyForce(force, true);
- }
- void btDeformableBackwardEulerObjective::initialGuess(TVStack& dv, const TVStack& residual)
- {
- size_t counter = 0;
- for (int i = 0; i < m_softBodies.size(); ++i)
- {
- btSoftBody* psb = m_softBodies[i];
- for (int j = 0; j < psb->m_nodes.size(); ++j)
- {
- dv[counter] = psb->m_nodes[j].m_im * residual[counter];
- ++counter;
- }
- }
- }
- //set constraints as projections
- void btDeformableBackwardEulerObjective::setConstraints(const btContactSolverInfo& infoGlobal)
- {
- m_projection.setConstraints(infoGlobal);
- }
- void btDeformableBackwardEulerObjective::applyDynamicFriction(TVStack& r)
- {
- m_projection.applyDynamicFriction(r);
- }
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