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Diffstat (limited to 'thirdparty/bullet/BulletSoftBody/btDeformableBackwardEulerObjective.cpp')
| -rw-r--r-- | thirdparty/bullet/BulletSoftBody/btDeformableBackwardEulerObjective.cpp | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/thirdparty/bullet/BulletSoftBody/btDeformableBackwardEulerObjective.cpp b/thirdparty/bullet/BulletSoftBody/btDeformableBackwardEulerObjective.cpp new file mode 100644 index 0000000000..1b247641aa --- /dev/null +++ b/thirdparty/bullet/BulletSoftBody/btDeformableBackwardEulerObjective.cpp @@ -0,0 +1,197 @@ +/* + 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_preconditioner = new MassPreconditioner(m_softBodies); +} + +btDeformableBackwardEulerObjective::~btDeformableBackwardEulerObjective() +{ + delete m_preconditioner; +} + +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); + } + 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); + if (m_implicit) + { + m_lf[i]->addScaledElasticForceDifferential(-m_dt*m_dt, x, b); + } + } +} + +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; + } + 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) + { + if (m_implicit) + { + 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(); + } + + for (int i = 0; i < m_lf.size(); ++i) + { + m_lf[i]->addScaledExplicitForce(m_dt, force); + } + 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() +{ + m_projection.setConstraints(); +} + +void btDeformableBackwardEulerObjective::applyDynamicFriction(TVStack& r) +{ + m_projection.applyDynamicFriction(r); +} |