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Diffstat (limited to 'thirdparty/bullet/BulletSoftBody/btDeformableMultiBodyDynamicsWorld.cpp')
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diff --git a/thirdparty/bullet/BulletSoftBody/btDeformableMultiBodyDynamicsWorld.cpp b/thirdparty/bullet/BulletSoftBody/btDeformableMultiBodyDynamicsWorld.cpp new file mode 100644 index 0000000000..618e5c0d7b --- /dev/null +++ b/thirdparty/bullet/BulletSoftBody/btDeformableMultiBodyDynamicsWorld.cpp @@ -0,0 +1,653 @@ +/* + 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. + */ + +/* ====== Overview of the Deformable Algorithm ====== */ + +/* +A single step of the deformable body simulation contains the following main components: +Call internalStepSimulation multiple times, to achieve 240Hz (4 steps of 60Hz). +1. Deformable maintaintenance of rest lengths and volume preservation. Forces only depend on position: Update velocity to a temporary state v_{n+1}^* = v_n + explicit_force * dt / mass, where explicit forces include gravity and elastic forces. +2. Detect discrete collisions between rigid and deformable bodies at position x_{n+1}^* = x_n + dt * v_{n+1}^*. + +3a. Solve all constraints, including LCP. Contact, position correction due to numerical drift, friction, and anchors for deformable. + TODO: add option for positional drift correction (using vel_target += erp * pos_error/dt + +3b. 5 Newton steps (multiple step). Conjugent Gradient solves linear system. Deformable Damping: Then velocities of deformable bodies v_{n+1} are solved in + M(v_{n+1} - v_{n+1}^*) = damping_force * dt / mass, + by a conjugate gradient solver, where the damping force is implicit and depends on v_{n+1}. + Make sure contact constraints are not violated in step b by performing velocity projections as in the paper by Baraff and Witkin https://www.cs.cmu.edu/~baraff/papers/sig98.pdf. Dynamic frictions are treated as a force and added to the rhs of the CG solve, whereas static frictions are treated as constraints similar to contact. +4. Position is updated via x_{n+1} = x_n + dt * v_{n+1}. + + +The algorithm also closely resembles the one in http://physbam.stanford.edu/~fedkiw/papers/stanford2008-03.pdf + */ + +#include <stdio.h> +#include "btDeformableMultiBodyDynamicsWorld.h" +#include "DeformableBodyInplaceSolverIslandCallback.h" +#include "btDeformableBodySolver.h" +#include "LinearMath/btQuickprof.h" +#include "btSoftBodyInternals.h" +btDeformableMultiBodyDynamicsWorld::btDeformableMultiBodyDynamicsWorld(btDispatcher* dispatcher, btBroadphaseInterface* pairCache, btDeformableMultiBodyConstraintSolver* constraintSolver, btCollisionConfiguration* collisionConfiguration, btDeformableBodySolver* deformableBodySolver) +: btMultiBodyDynamicsWorld(dispatcher, pairCache, (btMultiBodyConstraintSolver*)constraintSolver, collisionConfiguration), +m_deformableBodySolver(deformableBodySolver), m_solverCallback(0) +{ + m_drawFlags = fDrawFlags::Std; + m_drawNodeTree = true; + m_drawFaceTree = false; + m_drawClusterTree = false; + m_sbi.m_broadphase = pairCache; + m_sbi.m_dispatcher = dispatcher; + m_sbi.m_sparsesdf.Initialize(); + m_sbi.m_sparsesdf.setDefaultVoxelsz(0.005); + m_sbi.m_sparsesdf.Reset(); + + m_sbi.air_density = (btScalar)1.2; + m_sbi.water_density = 0; + m_sbi.water_offset = 0; + m_sbi.water_normal = btVector3(0, 0, 0); + m_sbi.m_gravity.setValue(0, -10, 0); + m_internalTime = 0.0; + m_implicit = false; + m_lineSearch = false; + m_selfCollision = true; + m_solverDeformableBodyIslandCallback = new DeformableBodyInplaceSolverIslandCallback(constraintSolver, dispatcher); +} + +void btDeformableMultiBodyDynamicsWorld::internalSingleStepSimulation(btScalar timeStep) +{ + BT_PROFILE("internalSingleStepSimulation"); + if (0 != m_internalPreTickCallback) + { + (*m_internalPreTickCallback)(this, timeStep); + } + reinitialize(timeStep); + // add gravity to velocity of rigid and multi bodys + applyRigidBodyGravity(timeStep); + + ///apply gravity and explicit force to velocity, predict motion + predictUnconstraintMotion(timeStep); + + ///perform collision detection + btMultiBodyDynamicsWorld::performDiscreteCollisionDetection(); + + if (m_selfCollision) + { + softBodySelfCollision(); + } + + btMultiBodyDynamicsWorld::calculateSimulationIslands(); + + beforeSolverCallbacks(timeStep); + + ///solve contact constraints and then deformable bodies momemtum equation + solveConstraints(timeStep); + + afterSolverCallbacks(timeStep); + + integrateTransforms(timeStep); + + ///update vehicle simulation + btMultiBodyDynamicsWorld::updateActions(timeStep); + + updateActivationState(timeStep); + // End solver-wise simulation step + // /////////////////////////////// +} + +void btDeformableMultiBodyDynamicsWorld::updateActivationState(btScalar timeStep) +{ + for (int i = 0; i < m_softBodies.size(); i++) + { + btSoftBody* psb = m_softBodies[i]; + psb->updateDeactivation(timeStep); + if (psb->wantsSleeping()) + { + if (psb->getActivationState() == ACTIVE_TAG) + psb->setActivationState(WANTS_DEACTIVATION); + if (psb->getActivationState() == ISLAND_SLEEPING) + { + psb->setZeroVelocity(); + } + } + else + { + if (psb->getActivationState() != DISABLE_DEACTIVATION) + psb->setActivationState(ACTIVE_TAG); + } + } + btMultiBodyDynamicsWorld::updateActivationState(timeStep); +} + + +void btDeformableMultiBodyDynamicsWorld::softBodySelfCollision() +{ + m_deformableBodySolver->updateSoftBodies(); + for (int i = 0; i < m_softBodies.size(); i++) + { + btSoftBody* psb = m_softBodies[i]; + if (psb->isActive()) + { + psb->defaultCollisionHandler(psb); + } + } +} + +void btDeformableMultiBodyDynamicsWorld::positionCorrection(btScalar timeStep) +{ + // correct the position of rigid bodies with temporary velocity generated from split impulse + btContactSolverInfo infoGlobal; + btVector3 zero(0,0,0); + for (int i = 0; i < m_nonStaticRigidBodies.size(); ++i) + { + btRigidBody* rb = m_nonStaticRigidBodies[i]; + //correct the position/orientation based on push/turn recovery + btTransform newTransform; + btVector3 pushVelocity = rb->getPushVelocity(); + btVector3 turnVelocity = rb->getTurnVelocity(); + if (pushVelocity[0] != 0.f || pushVelocity[1] != 0 || pushVelocity[2] != 0 || turnVelocity[0] != 0.f || turnVelocity[1] != 0 || turnVelocity[2] != 0) + { + btTransformUtil::integrateTransform(rb->getWorldTransform(), pushVelocity, turnVelocity * infoGlobal.m_splitImpulseTurnErp, timeStep, newTransform); + rb->setWorldTransform(newTransform); + rb->setPushVelocity(zero); + rb->setTurnVelocity(zero); + } + } +} + +void btDeformableMultiBodyDynamicsWorld::integrateTransforms(btScalar timeStep) +{ + BT_PROFILE("integrateTransforms"); + positionCorrection(timeStep); + btMultiBodyDynamicsWorld::integrateTransforms(timeStep); + 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]; + btScalar maxDisplacement = psb->getWorldInfo()->m_maxDisplacement; + btScalar clampDeltaV = maxDisplacement / timeStep; + for (int c = 0; c < 3; c++) + { + if (node.m_v[c] > clampDeltaV) + { + node.m_v[c] = clampDeltaV; + } + if (node.m_v[c] < -clampDeltaV) + { + node.m_v[c] = -clampDeltaV; + } + } + node.m_x = node.m_x + timeStep * node.m_v; + node.m_v -= node.m_vsplit; + node.m_vsplit.setZero(); + node.m_q = node.m_x; + node.m_vn = node.m_v; + } + // enforce anchor constraints + for (int j = 0; j < psb->m_deformableAnchors.size();++j) + { + btSoftBody::DeformableNodeRigidAnchor& a = psb->m_deformableAnchors[j]; + btSoftBody::Node* n = a.m_node; + n->m_x = a.m_cti.m_colObj->getWorldTransform() * a.m_local; + + // update multibody anchor info + if (a.m_cti.m_colObj->getInternalType() == btCollisionObject::CO_FEATHERSTONE_LINK) + { + btMultiBodyLinkCollider* multibodyLinkCol = (btMultiBodyLinkCollider*)btMultiBodyLinkCollider::upcast(a.m_cti.m_colObj); + if (multibodyLinkCol) + { + btVector3 nrm; + const btCollisionShape* shp = multibodyLinkCol->getCollisionShape(); + const btTransform& wtr = multibodyLinkCol->getWorldTransform(); + psb->m_worldInfo->m_sparsesdf.Evaluate( + wtr.invXform(n->m_x), + shp, + nrm, + 0); + a.m_cti.m_normal = wtr.getBasis() * nrm; + btVector3 normal = a.m_cti.m_normal; + btVector3 t1 = generateUnitOrthogonalVector(normal); + btVector3 t2 = btCross(normal, t1); + btMultiBodyJacobianData jacobianData_normal, jacobianData_t1, jacobianData_t2; + findJacobian(multibodyLinkCol, jacobianData_normal, a.m_node->m_x, normal); + findJacobian(multibodyLinkCol, jacobianData_t1, a.m_node->m_x, t1); + findJacobian(multibodyLinkCol, jacobianData_t2, a.m_node->m_x, t2); + + btScalar* J_n = &jacobianData_normal.m_jacobians[0]; + btScalar* J_t1 = &jacobianData_t1.m_jacobians[0]; + btScalar* J_t2 = &jacobianData_t2.m_jacobians[0]; + + btScalar* u_n = &jacobianData_normal.m_deltaVelocitiesUnitImpulse[0]; + btScalar* u_t1 = &jacobianData_t1.m_deltaVelocitiesUnitImpulse[0]; + btScalar* u_t2 = &jacobianData_t2.m_deltaVelocitiesUnitImpulse[0]; + + btMatrix3x3 rot(normal.getX(), normal.getY(), normal.getZ(), + t1.getX(), t1.getY(), t1.getZ(), + t2.getX(), t2.getY(), t2.getZ()); // world frame to local frame + const int ndof = multibodyLinkCol->m_multiBody->getNumDofs() + 6; + btMatrix3x3 local_impulse_matrix = (Diagonal(n->m_im) + OuterProduct(J_n, J_t1, J_t2, u_n, u_t1, u_t2, ndof)).inverse(); + a.m_c0 = rot.transpose() * local_impulse_matrix * rot; + a.jacobianData_normal = jacobianData_normal; + a.jacobianData_t1 = jacobianData_t1; + a.jacobianData_t2 = jacobianData_t2; + a.t1 = t1; + a.t2 = t2; + } + } + } + psb->interpolateRenderMesh(); + } +} + +void btDeformableMultiBodyDynamicsWorld::solveConstraints(btScalar timeStep) +{ + // save v_{n+1}^* velocity after explicit forces + m_deformableBodySolver->backupVelocity(); + + // set up constraints among multibodies and between multibodies and deformable bodies + setupConstraints(); + + // solve contact constraints + solveContactConstraints(); + + // set up the directions in which the velocity does not change in the momentum solve + m_deformableBodySolver->m_objective->m_projection.setProjection(); + + // for explicit scheme, m_backupVelocity = v_{n+1}^* + // for implicit scheme, m_backupVelocity = v_n + // Here, set dv = v_{n+1} - v_n for nodes in contact + m_deformableBodySolver->setupDeformableSolve(m_implicit); + + // At this point, dv should be golden for nodes in contact + // proceed to solve deformable momentum equation + m_deformableBodySolver->solveDeformableConstraints(timeStep); +} + +void btDeformableMultiBodyDynamicsWorld::setupConstraints() +{ + // set up constraints between multibody and deformable bodies + m_deformableBodySolver->setConstraints(); + + // set up constraints among multibodies + { + sortConstraints(); + // setup the solver callback + btMultiBodyConstraint** sortedMultiBodyConstraints = m_sortedMultiBodyConstraints.size() ? &m_sortedMultiBodyConstraints[0] : 0; + btTypedConstraint** constraintsPtr = getNumConstraints() ? &m_sortedConstraints[0] : 0; + m_solverDeformableBodyIslandCallback->setup(&m_solverInfo, constraintsPtr, m_sortedConstraints.size(), sortedMultiBodyConstraints, m_sortedMultiBodyConstraints.size(), getDebugDrawer()); + + // build islands + m_islandManager->buildIslands(getCollisionWorld()->getDispatcher(), getCollisionWorld()); + } +} + +void btDeformableMultiBodyDynamicsWorld::sortConstraints() +{ + m_sortedConstraints.resize(m_constraints.size()); + int i; + for (i = 0; i < getNumConstraints(); i++) + { + m_sortedConstraints[i] = m_constraints[i]; + } + m_sortedConstraints.quickSort(btSortConstraintOnIslandPredicate2()); + + m_sortedMultiBodyConstraints.resize(m_multiBodyConstraints.size()); + for (i = 0; i < m_multiBodyConstraints.size(); i++) + { + m_sortedMultiBodyConstraints[i] = m_multiBodyConstraints[i]; + } + m_sortedMultiBodyConstraints.quickSort(btSortMultiBodyConstraintOnIslandPredicate()); +} + + +void btDeformableMultiBodyDynamicsWorld::solveContactConstraints() +{ + // process constraints on each island + m_islandManager->processIslands(getCollisionWorld()->getDispatcher(), getCollisionWorld(), m_solverDeformableBodyIslandCallback); + + // process deferred + m_solverDeformableBodyIslandCallback->processConstraints(); + m_constraintSolver->allSolved(m_solverInfo, m_debugDrawer); + + // write joint feedback + { + for (int i = 0; i < this->m_multiBodies.size(); i++) + { + btMultiBody* bod = m_multiBodies[i]; + + bool isSleeping = false; + + if (bod->getBaseCollider() && bod->getBaseCollider()->getActivationState() == ISLAND_SLEEPING) + { + isSleeping = true; + } + for (int b = 0; b < bod->getNumLinks(); b++) + { + if (bod->getLink(b).m_collider && bod->getLink(b).m_collider->getActivationState() == ISLAND_SLEEPING) + isSleeping = true; + } + + if (!isSleeping) + { + //useless? they get resized in stepVelocities once again (AND DIFFERENTLY) + m_scratch_r.resize(bod->getNumLinks() + 1); //multidof? ("Y"s use it and it is used to store qdd) + m_scratch_v.resize(bod->getNumLinks() + 1); + m_scratch_m.resize(bod->getNumLinks() + 1); + + if (bod->internalNeedsJointFeedback()) + { + if (!bod->isUsingRK4Integration()) + { + if (bod->internalNeedsJointFeedback()) + { + bool isConstraintPass = true; + bod->computeAccelerationsArticulatedBodyAlgorithmMultiDof(m_solverInfo.m_timeStep, m_scratch_r, m_scratch_v, m_scratch_m, isConstraintPass, + getSolverInfo().m_jointFeedbackInWorldSpace, + getSolverInfo().m_jointFeedbackInJointFrame); + } + } + } + } + } + } + + for (int i = 0; i < this->m_multiBodies.size(); i++) + { + btMultiBody* bod = m_multiBodies[i]; + bod->processDeltaVeeMultiDof2(); + } +} + +void btDeformableMultiBodyDynamicsWorld::addSoftBody(btSoftBody* body, int collisionFilterGroup, int collisionFilterMask) +{ + m_softBodies.push_back(body); + + // Set the soft body solver that will deal with this body + // to be the world's solver + body->setSoftBodySolver(m_deformableBodySolver); + + btCollisionWorld::addCollisionObject(body, + collisionFilterGroup, + collisionFilterMask); +} + +void btDeformableMultiBodyDynamicsWorld::predictUnconstraintMotion(btScalar timeStep) +{ + BT_PROFILE("predictUnconstraintMotion"); + btMultiBodyDynamicsWorld::predictUnconstraintMotion(timeStep); + m_deformableBodySolver->predictMotion(timeStep); +} + +void btDeformableMultiBodyDynamicsWorld::reinitialize(btScalar timeStep) +{ + m_internalTime += timeStep; + m_deformableBodySolver->setImplicit(m_implicit); + m_deformableBodySolver->setLineSearch(m_lineSearch); + m_deformableBodySolver->reinitialize(m_softBodies, timeStep); + btDispatcherInfo& dispatchInfo = btMultiBodyDynamicsWorld::getDispatchInfo(); + dispatchInfo.m_timeStep = timeStep; + dispatchInfo.m_stepCount = 0; + dispatchInfo.m_debugDraw = btMultiBodyDynamicsWorld::getDebugDrawer(); + btMultiBodyDynamicsWorld::getSolverInfo().m_timeStep = timeStep; +} + + +void btDeformableMultiBodyDynamicsWorld::debugDrawWorld() +{ + + btMultiBodyDynamicsWorld::debugDrawWorld(); + + for (int i = 0; i < getSoftBodyArray().size(); i++) + { + btSoftBody* psb = (btSoftBody*)getSoftBodyArray()[i]; + { + btSoftBodyHelpers::DrawFrame(psb, getDebugDrawer()); + btSoftBodyHelpers::Draw(psb, getDebugDrawer(), getDrawFlags()); + } + } + + +} + +void btDeformableMultiBodyDynamicsWorld::applyRigidBodyGravity(btScalar timeStep) +{ + // Gravity is applied in stepSimulation and then cleared here and then applied here and then cleared here again + // so that 1) gravity is applied to velocity before constraint solve and 2) gravity is applied in each substep + // when there are multiple substeps + btMultiBodyDynamicsWorld::applyGravity(); + // integrate rigid body gravity + for (int i = 0; i < m_nonStaticRigidBodies.size(); ++i) + { + btRigidBody* rb = m_nonStaticRigidBodies[i]; + rb->integrateVelocities(timeStep); + } + + // integrate multibody gravity + { + forwardKinematics(); + clearMultiBodyConstraintForces(); + { + for (int i = 0; i < this->m_multiBodies.size(); i++) + { + btMultiBody* bod = m_multiBodies[i]; + + bool isSleeping = false; + + if (bod->getBaseCollider() && bod->getBaseCollider()->getActivationState() == ISLAND_SLEEPING) + { + isSleeping = true; + } + for (int b = 0; b < bod->getNumLinks(); b++) + { + if (bod->getLink(b).m_collider && bod->getLink(b).m_collider->getActivationState() == ISLAND_SLEEPING) + isSleeping = true; + } + + if (!isSleeping) + { + m_scratch_r.resize(bod->getNumLinks() + 1); + m_scratch_v.resize(bod->getNumLinks() + 1); + m_scratch_m.resize(bod->getNumLinks() + 1); + bool isConstraintPass = false; + { + if (!bod->isUsingRK4Integration()) + { + bod->computeAccelerationsArticulatedBodyAlgorithmMultiDof(m_solverInfo.m_timeStep, + m_scratch_r, m_scratch_v, m_scratch_m,isConstraintPass, + getSolverInfo().m_jointFeedbackInWorldSpace, + getSolverInfo().m_jointFeedbackInJointFrame); + } + else + { + btAssert(" RK4Integration is not supported" ); + } + } + } + } + } + } + clearGravity(); +} + +void btDeformableMultiBodyDynamicsWorld::clearGravity() +{ + BT_PROFILE("btMultiBody clearGravity"); + // clear rigid body gravity + for (int i = 0; i < m_nonStaticRigidBodies.size(); i++) + { + btRigidBody* body = m_nonStaticRigidBodies[i]; + if (body->isActive()) + { + body->clearGravity(); + } + } + // clear multibody gravity + for (int i = 0; i < this->m_multiBodies.size(); i++) + { + btMultiBody* bod = m_multiBodies[i]; + + bool isSleeping = false; + + if (bod->getBaseCollider() && bod->getBaseCollider()->getActivationState() == ISLAND_SLEEPING) + { + isSleeping = true; + } + for (int b = 0; b < bod->getNumLinks(); b++) + { + if (bod->getLink(b).m_collider && bod->getLink(b).m_collider->getActivationState() == ISLAND_SLEEPING) + isSleeping = true; + } + + if (!isSleeping) + { + bod->addBaseForce(-m_gravity * bod->getBaseMass()); + + for (int j = 0; j < bod->getNumLinks(); ++j) + { + bod->addLinkForce(j, -m_gravity * bod->getLinkMass(j)); + } + } + } +} + +void btDeformableMultiBodyDynamicsWorld::beforeSolverCallbacks(btScalar timeStep) +{ + if (0 != m_internalTickCallback) + { + (*m_internalTickCallback)(this, timeStep); + } + + if (0 != m_solverCallback) + { + (*m_solverCallback)(m_internalTime, this); + } +} + +void btDeformableMultiBodyDynamicsWorld::afterSolverCallbacks(btScalar timeStep) +{ + if (0 != m_solverCallback) + { + (*m_solverCallback)(m_internalTime, this); + } +} + +void btDeformableMultiBodyDynamicsWorld::addForce(btSoftBody* psb, btDeformableLagrangianForce* force) +{ + btAlignedObjectArray<btDeformableLagrangianForce*>& forces = m_deformableBodySolver->m_objective->m_lf; + bool added = false; + for (int i = 0; i < forces.size(); ++i) + { + if (forces[i]->getForceType() == force->getForceType()) + { + forces[i]->addSoftBody(psb); + added = true; + break; + } + } + if (!added) + { + force->addSoftBody(psb); + force->setIndices(m_deformableBodySolver->m_objective->getIndices()); + forces.push_back(force); + } +} + +void btDeformableMultiBodyDynamicsWorld::removeSoftBody(btSoftBody* body) +{ + m_softBodies.remove(body); + btCollisionWorld::removeCollisionObject(body); + // force a reinitialize so that node indices get updated. + m_deformableBodySolver->reinitialize(m_softBodies, btScalar(-1)); +} + +void btDeformableMultiBodyDynamicsWorld::removeCollisionObject(btCollisionObject* collisionObject) +{ + btSoftBody* body = btSoftBody::upcast(collisionObject); + if (body) + removeSoftBody(body); + else + btDiscreteDynamicsWorld::removeCollisionObject(collisionObject); +} + + +int btDeformableMultiBodyDynamicsWorld::stepSimulation(btScalar timeStep, int maxSubSteps, btScalar fixedTimeStep) +{ + startProfiling(timeStep); + + int numSimulationSubSteps = 0; + + if (maxSubSteps) + { + //fixed timestep with interpolation + m_fixedTimeStep = fixedTimeStep; + m_localTime += timeStep; + if (m_localTime >= fixedTimeStep) + { + numSimulationSubSteps = int(m_localTime / fixedTimeStep); + m_localTime -= numSimulationSubSteps * fixedTimeStep; + } + } + else + { + //variable timestep + fixedTimeStep = timeStep; + m_localTime = m_latencyMotionStateInterpolation ? 0 : timeStep; + m_fixedTimeStep = 0; + if (btFuzzyZero(timeStep)) + { + numSimulationSubSteps = 0; + maxSubSteps = 0; + } + else + { + numSimulationSubSteps = 1; + maxSubSteps = 1; + } + } + + //process some debugging flags + if (getDebugDrawer()) + { + btIDebugDraw* debugDrawer = getDebugDrawer(); + gDisableDeactivation = (debugDrawer->getDebugMode() & btIDebugDraw::DBG_NoDeactivation) != 0; + } + if (numSimulationSubSteps) + { + //clamp the number of substeps, to prevent simulation grinding spiralling down to a halt + int clampedSimulationSteps = (numSimulationSubSteps > maxSubSteps) ? maxSubSteps : numSimulationSubSteps; + + saveKinematicState(fixedTimeStep * clampedSimulationSteps); + + for (int i = 0; i < clampedSimulationSteps; i++) + { + internalSingleStepSimulation(fixedTimeStep); + synchronizeMotionStates(); + } + } + else + { + synchronizeMotionStates(); + } + + clearForces(); + +#ifndef BT_NO_PROFILE + CProfileManager::Increment_Frame_Counter(); +#endif //BT_NO_PROFILE + + return numSimulationSubSteps; +} |