653 lines
25 KiB
C++
653 lines
25 KiB
C++
/*
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Written by Xuchen Han <xuchenhan2015@u.northwestern.edu>
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Bullet Continuous Collision Detection and Physics Library
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Copyright (c) 2019 Google Inc. http://bulletphysics.org
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This software is provided 'as-is', without any express or implied warranty.
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In no event will the authors be held liable for any damages arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it freely,
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subject to the following restrictions:
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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.
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2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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*/
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/* ====== Overview of the Deformable Algorithm ====== */
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/*
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A single step of the deformable body simulation contains the following main components:
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Call internalStepSimulation multiple times, to achieve 240Hz (4 steps of 60Hz).
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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.
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2. Detect discrete collisions between rigid and deformable bodies at position x_{n+1}^* = x_n + dt * v_{n+1}^*.
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3a. Solve all constraints, including LCP. Contact, position correction due to numerical drift, friction, and anchors for deformable.
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TODO: add option for positional drift correction (using vel_target += erp * pos_error/dt
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3b. 5 Newton steps (multiple step). Conjugent Gradient solves linear system. Deformable Damping: Then velocities of deformable bodies v_{n+1} are solved in
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M(v_{n+1} - v_{n+1}^*) = damping_force * dt / mass,
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by a conjugate gradient solver, where the damping force is implicit and depends on v_{n+1}.
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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.
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4. Position is updated via x_{n+1} = x_n + dt * v_{n+1}.
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The algorithm also closely resembles the one in http://physbam.stanford.edu/~fedkiw/papers/stanford2008-03.pdf
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*/
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#include <stdio.h>
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#include "btDeformableMultiBodyDynamicsWorld.h"
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#include "DeformableBodyInplaceSolverIslandCallback.h"
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#include "btDeformableBodySolver.h"
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#include "LinearMath/btQuickprof.h"
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#include "btSoftBodyInternals.h"
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btDeformableMultiBodyDynamicsWorld::btDeformableMultiBodyDynamicsWorld(btDispatcher* dispatcher, btBroadphaseInterface* pairCache, btDeformableMultiBodyConstraintSolver* constraintSolver, btCollisionConfiguration* collisionConfiguration, btDeformableBodySolver* deformableBodySolver)
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: btMultiBodyDynamicsWorld(dispatcher, pairCache, (btMultiBodyConstraintSolver*)constraintSolver, collisionConfiguration),
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m_deformableBodySolver(deformableBodySolver), m_solverCallback(0)
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{
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m_drawFlags = fDrawFlags::Std;
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m_drawNodeTree = true;
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m_drawFaceTree = false;
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m_drawClusterTree = false;
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m_sbi.m_broadphase = pairCache;
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m_sbi.m_dispatcher = dispatcher;
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m_sbi.m_sparsesdf.Initialize();
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m_sbi.m_sparsesdf.setDefaultVoxelsz(0.005);
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m_sbi.m_sparsesdf.Reset();
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m_sbi.air_density = (btScalar)1.2;
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m_sbi.water_density = 0;
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m_sbi.water_offset = 0;
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m_sbi.water_normal = btVector3(0, 0, 0);
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m_sbi.m_gravity.setValue(0, -10, 0);
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m_internalTime = 0.0;
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m_implicit = false;
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m_lineSearch = false;
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m_selfCollision = true;
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m_solverDeformableBodyIslandCallback = new DeformableBodyInplaceSolverIslandCallback(constraintSolver, dispatcher);
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}
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void btDeformableMultiBodyDynamicsWorld::internalSingleStepSimulation(btScalar timeStep)
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{
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BT_PROFILE("internalSingleStepSimulation");
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if (0 != m_internalPreTickCallback)
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{
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(*m_internalPreTickCallback)(this, timeStep);
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}
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reinitialize(timeStep);
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// add gravity to velocity of rigid and multi bodys
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applyRigidBodyGravity(timeStep);
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///apply gravity and explicit force to velocity, predict motion
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predictUnconstraintMotion(timeStep);
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///perform collision detection
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btMultiBodyDynamicsWorld::performDiscreteCollisionDetection();
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if (m_selfCollision)
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{
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softBodySelfCollision();
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}
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btMultiBodyDynamicsWorld::calculateSimulationIslands();
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beforeSolverCallbacks(timeStep);
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///solve contact constraints and then deformable bodies momemtum equation
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solveConstraints(timeStep);
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afterSolverCallbacks(timeStep);
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integrateTransforms(timeStep);
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///update vehicle simulation
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btMultiBodyDynamicsWorld::updateActions(timeStep);
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updateActivationState(timeStep);
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// End solver-wise simulation step
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// ///////////////////////////////
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}
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void btDeformableMultiBodyDynamicsWorld::updateActivationState(btScalar timeStep)
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{
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for (int i = 0; i < m_softBodies.size(); i++)
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{
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btSoftBody* psb = m_softBodies[i];
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psb->updateDeactivation(timeStep);
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if (psb->wantsSleeping())
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{
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if (psb->getActivationState() == ACTIVE_TAG)
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psb->setActivationState(WANTS_DEACTIVATION);
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if (psb->getActivationState() == ISLAND_SLEEPING)
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{
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psb->setZeroVelocity();
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}
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}
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else
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{
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if (psb->getActivationState() != DISABLE_DEACTIVATION)
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psb->setActivationState(ACTIVE_TAG);
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}
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}
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btMultiBodyDynamicsWorld::updateActivationState(timeStep);
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}
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void btDeformableMultiBodyDynamicsWorld::softBodySelfCollision()
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{
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m_deformableBodySolver->updateSoftBodies();
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for (int i = 0; i < m_softBodies.size(); i++)
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{
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btSoftBody* psb = m_softBodies[i];
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if (psb->isActive())
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{
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psb->defaultCollisionHandler(psb);
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}
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}
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}
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void btDeformableMultiBodyDynamicsWorld::positionCorrection(btScalar timeStep)
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{
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// correct the position of rigid bodies with temporary velocity generated from split impulse
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btContactSolverInfo infoGlobal;
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btVector3 zero(0,0,0);
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for (int i = 0; i < m_nonStaticRigidBodies.size(); ++i)
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{
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btRigidBody* rb = m_nonStaticRigidBodies[i];
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//correct the position/orientation based on push/turn recovery
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btTransform newTransform;
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btVector3 pushVelocity = rb->getPushVelocity();
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btVector3 turnVelocity = rb->getTurnVelocity();
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if (pushVelocity[0] != 0.f || pushVelocity[1] != 0 || pushVelocity[2] != 0 || turnVelocity[0] != 0.f || turnVelocity[1] != 0 || turnVelocity[2] != 0)
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{
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btTransformUtil::integrateTransform(rb->getWorldTransform(), pushVelocity, turnVelocity * infoGlobal.m_splitImpulseTurnErp, timeStep, newTransform);
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rb->setWorldTransform(newTransform);
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rb->setPushVelocity(zero);
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rb->setTurnVelocity(zero);
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}
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}
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}
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void btDeformableMultiBodyDynamicsWorld::integrateTransforms(btScalar timeStep)
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{
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BT_PROFILE("integrateTransforms");
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positionCorrection(timeStep);
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btMultiBodyDynamicsWorld::integrateTransforms(timeStep);
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for (int i = 0; i < m_softBodies.size(); ++i)
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{
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btSoftBody* psb = m_softBodies[i];
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for (int j = 0; j < psb->m_nodes.size(); ++j)
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{
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btSoftBody::Node& node = psb->m_nodes[j];
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btScalar maxDisplacement = psb->getWorldInfo()->m_maxDisplacement;
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btScalar clampDeltaV = maxDisplacement / timeStep;
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for (int c = 0; c < 3; c++)
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{
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if (node.m_v[c] > clampDeltaV)
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{
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node.m_v[c] = clampDeltaV;
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}
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if (node.m_v[c] < -clampDeltaV)
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{
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node.m_v[c] = -clampDeltaV;
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}
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}
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node.m_x = node.m_x + timeStep * node.m_v;
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node.m_v -= node.m_vsplit;
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node.m_vsplit.setZero();
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node.m_q = node.m_x;
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node.m_vn = node.m_v;
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}
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// enforce anchor constraints
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for (int j = 0; j < psb->m_deformableAnchors.size();++j)
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{
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btSoftBody::DeformableNodeRigidAnchor& a = psb->m_deformableAnchors[j];
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btSoftBody::Node* n = a.m_node;
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n->m_x = a.m_cti.m_colObj->getWorldTransform() * a.m_local;
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// update multibody anchor info
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if (a.m_cti.m_colObj->getInternalType() == btCollisionObject::CO_FEATHERSTONE_LINK)
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{
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btMultiBodyLinkCollider* multibodyLinkCol = (btMultiBodyLinkCollider*)btMultiBodyLinkCollider::upcast(a.m_cti.m_colObj);
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if (multibodyLinkCol)
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{
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btVector3 nrm;
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const btCollisionShape* shp = multibodyLinkCol->getCollisionShape();
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const btTransform& wtr = multibodyLinkCol->getWorldTransform();
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psb->m_worldInfo->m_sparsesdf.Evaluate(
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wtr.invXform(n->m_x),
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shp,
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nrm,
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0);
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a.m_cti.m_normal = wtr.getBasis() * nrm;
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btVector3 normal = a.m_cti.m_normal;
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btVector3 t1 = generateUnitOrthogonalVector(normal);
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btVector3 t2 = btCross(normal, t1);
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btMultiBodyJacobianData jacobianData_normal, jacobianData_t1, jacobianData_t2;
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findJacobian(multibodyLinkCol, jacobianData_normal, a.m_node->m_x, normal);
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findJacobian(multibodyLinkCol, jacobianData_t1, a.m_node->m_x, t1);
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findJacobian(multibodyLinkCol, jacobianData_t2, a.m_node->m_x, t2);
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btScalar* J_n = &jacobianData_normal.m_jacobians[0];
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btScalar* J_t1 = &jacobianData_t1.m_jacobians[0];
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btScalar* J_t2 = &jacobianData_t2.m_jacobians[0];
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btScalar* u_n = &jacobianData_normal.m_deltaVelocitiesUnitImpulse[0];
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btScalar* u_t1 = &jacobianData_t1.m_deltaVelocitiesUnitImpulse[0];
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btScalar* u_t2 = &jacobianData_t2.m_deltaVelocitiesUnitImpulse[0];
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btMatrix3x3 rot(normal.getX(), normal.getY(), normal.getZ(),
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t1.getX(), t1.getY(), t1.getZ(),
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t2.getX(), t2.getY(), t2.getZ()); // world frame to local frame
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const int ndof = multibodyLinkCol->m_multiBody->getNumDofs() + 6;
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btMatrix3x3 local_impulse_matrix = (Diagonal(n->m_im) + OuterProduct(J_n, J_t1, J_t2, u_n, u_t1, u_t2, ndof)).inverse();
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a.m_c0 = rot.transpose() * local_impulse_matrix * rot;
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a.jacobianData_normal = jacobianData_normal;
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a.jacobianData_t1 = jacobianData_t1;
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a.jacobianData_t2 = jacobianData_t2;
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a.t1 = t1;
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a.t2 = t2;
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}
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}
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}
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psb->interpolateRenderMesh();
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}
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}
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void btDeformableMultiBodyDynamicsWorld::solveConstraints(btScalar timeStep)
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{
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// save v_{n+1}^* velocity after explicit forces
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m_deformableBodySolver->backupVelocity();
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// set up constraints among multibodies and between multibodies and deformable bodies
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setupConstraints();
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// solve contact constraints
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solveContactConstraints();
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// set up the directions in which the velocity does not change in the momentum solve
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m_deformableBodySolver->m_objective->m_projection.setProjection();
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// for explicit scheme, m_backupVelocity = v_{n+1}^*
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// for implicit scheme, m_backupVelocity = v_n
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// Here, set dv = v_{n+1} - v_n for nodes in contact
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m_deformableBodySolver->setupDeformableSolve(m_implicit);
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// At this point, dv should be golden for nodes in contact
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// proceed to solve deformable momentum equation
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m_deformableBodySolver->solveDeformableConstraints(timeStep);
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}
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void btDeformableMultiBodyDynamicsWorld::setupConstraints()
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{
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// set up constraints between multibody and deformable bodies
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m_deformableBodySolver->setConstraints();
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// set up constraints among multibodies
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{
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sortConstraints();
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// setup the solver callback
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btMultiBodyConstraint** sortedMultiBodyConstraints = m_sortedMultiBodyConstraints.size() ? &m_sortedMultiBodyConstraints[0] : 0;
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btTypedConstraint** constraintsPtr = getNumConstraints() ? &m_sortedConstraints[0] : 0;
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m_solverDeformableBodyIslandCallback->setup(&m_solverInfo, constraintsPtr, m_sortedConstraints.size(), sortedMultiBodyConstraints, m_sortedMultiBodyConstraints.size(), getDebugDrawer());
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// build islands
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m_islandManager->buildIslands(getCollisionWorld()->getDispatcher(), getCollisionWorld());
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}
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}
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void btDeformableMultiBodyDynamicsWorld::sortConstraints()
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{
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m_sortedConstraints.resize(m_constraints.size());
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int i;
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for (i = 0; i < getNumConstraints(); i++)
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{
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m_sortedConstraints[i] = m_constraints[i];
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}
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m_sortedConstraints.quickSort(btSortConstraintOnIslandPredicate2());
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m_sortedMultiBodyConstraints.resize(m_multiBodyConstraints.size());
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for (i = 0; i < m_multiBodyConstraints.size(); i++)
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{
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m_sortedMultiBodyConstraints[i] = m_multiBodyConstraints[i];
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}
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m_sortedMultiBodyConstraints.quickSort(btSortMultiBodyConstraintOnIslandPredicate());
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}
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void btDeformableMultiBodyDynamicsWorld::solveContactConstraints()
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{
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// process constraints on each island
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m_islandManager->processIslands(getCollisionWorld()->getDispatcher(), getCollisionWorld(), m_solverDeformableBodyIslandCallback);
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// process deferred
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m_solverDeformableBodyIslandCallback->processConstraints();
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m_constraintSolver->allSolved(m_solverInfo, m_debugDrawer);
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// write joint feedback
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{
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for (int i = 0; i < this->m_multiBodies.size(); i++)
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{
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btMultiBody* bod = m_multiBodies[i];
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bool isSleeping = false;
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if (bod->getBaseCollider() && bod->getBaseCollider()->getActivationState() == ISLAND_SLEEPING)
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{
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isSleeping = true;
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}
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for (int b = 0; b < bod->getNumLinks(); b++)
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{
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if (bod->getLink(b).m_collider && bod->getLink(b).m_collider->getActivationState() == ISLAND_SLEEPING)
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isSleeping = true;
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}
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if (!isSleeping)
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{
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//useless? they get resized in stepVelocities once again (AND DIFFERENTLY)
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m_scratch_r.resize(bod->getNumLinks() + 1); //multidof? ("Y"s use it and it is used to store qdd)
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m_scratch_v.resize(bod->getNumLinks() + 1);
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m_scratch_m.resize(bod->getNumLinks() + 1);
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if (bod->internalNeedsJointFeedback())
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{
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if (!bod->isUsingRK4Integration())
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{
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if (bod->internalNeedsJointFeedback())
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{
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bool isConstraintPass = true;
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bod->computeAccelerationsArticulatedBodyAlgorithmMultiDof(m_solverInfo.m_timeStep, m_scratch_r, m_scratch_v, m_scratch_m, isConstraintPass,
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getSolverInfo().m_jointFeedbackInWorldSpace,
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getSolverInfo().m_jointFeedbackInJointFrame);
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}
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}
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}
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}
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}
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}
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for (int i = 0; i < this->m_multiBodies.size(); i++)
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{
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btMultiBody* bod = m_multiBodies[i];
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bod->processDeltaVeeMultiDof2();
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}
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}
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void btDeformableMultiBodyDynamicsWorld::addSoftBody(btSoftBody* body, int collisionFilterGroup, int collisionFilterMask)
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{
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m_softBodies.push_back(body);
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// Set the soft body solver that will deal with this body
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// to be the world's solver
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body->setSoftBodySolver(m_deformableBodySolver);
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btCollisionWorld::addCollisionObject(body,
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collisionFilterGroup,
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collisionFilterMask);
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}
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void btDeformableMultiBodyDynamicsWorld::predictUnconstraintMotion(btScalar timeStep)
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{
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BT_PROFILE("predictUnconstraintMotion");
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btMultiBodyDynamicsWorld::predictUnconstraintMotion(timeStep);
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m_deformableBodySolver->predictMotion(timeStep);
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}
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void btDeformableMultiBodyDynamicsWorld::reinitialize(btScalar timeStep)
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{
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m_internalTime += timeStep;
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m_deformableBodySolver->setImplicit(m_implicit);
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m_deformableBodySolver->setLineSearch(m_lineSearch);
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m_deformableBodySolver->reinitialize(m_softBodies, timeStep);
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btDispatcherInfo& dispatchInfo = btMultiBodyDynamicsWorld::getDispatchInfo();
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dispatchInfo.m_timeStep = timeStep;
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dispatchInfo.m_stepCount = 0;
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dispatchInfo.m_debugDraw = btMultiBodyDynamicsWorld::getDebugDrawer();
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btMultiBodyDynamicsWorld::getSolverInfo().m_timeStep = timeStep;
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}
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void btDeformableMultiBodyDynamicsWorld::debugDrawWorld()
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{
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btMultiBodyDynamicsWorld::debugDrawWorld();
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for (int i = 0; i < getSoftBodyArray().size(); i++)
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{
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btSoftBody* psb = (btSoftBody*)getSoftBodyArray()[i];
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{
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btSoftBodyHelpers::DrawFrame(psb, getDebugDrawer());
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btSoftBodyHelpers::Draw(psb, getDebugDrawer(), getDrawFlags());
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}
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}
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}
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void btDeformableMultiBodyDynamicsWorld::applyRigidBodyGravity(btScalar timeStep)
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{
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// Gravity is applied in stepSimulation and then cleared here and then applied here and then cleared here again
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// so that 1) gravity is applied to velocity before constraint solve and 2) gravity is applied in each substep
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// when there are multiple substeps
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btMultiBodyDynamicsWorld::applyGravity();
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// integrate rigid body gravity
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for (int i = 0; i < m_nonStaticRigidBodies.size(); ++i)
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{
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btRigidBody* rb = m_nonStaticRigidBodies[i];
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rb->integrateVelocities(timeStep);
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}
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// integrate multibody gravity
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{
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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;
|
|
}
|