Added a first version of a Featherstone multi body implementation.
The original version was written by Stephen Thompson. I replaced Eigen math by Bullet LinearMath, and added a dedicated 6x6 matrix solver. Also I integrated support for collisions/contact constraints between btMultiBody and btRigidBody, and de-activation support. See Demos/FeatherstoneMultiBodyDemo/Win32FeatherstoneMultiBodyDemo.cpp for example usage. There is currently only support for contact constraints for btMultiBody. Next on the list will be adding support for joint limit constraint for btMultiBody. The implementation is still experimental/untested, the quality will improve in upcoming Bullet releases.
This commit is contained in:
erwin.coumans
265
src/BulletDynamics/Featherstone/btMultiBodyDynamicsWorld.cpp
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265
src/BulletDynamics/Featherstone/btMultiBodyDynamicsWorld.cpp
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/*
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Bullet Continuous Collision Detection and Physics Library
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Copyright (c) 2013 Erwin Coumans 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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#include "btMultiBodyDynamicsWorld.h"
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#include "btMultiBodyConstraintSolver.h"
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#include "btMultiBody.h"
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#include "btMultiBodyLinkCollider.h"
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#include "BulletCollision/CollisionDispatch/btSimulationIslandManager.h"
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#include "LinearMath/btQuickprof.h"
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btMultiBodyDynamicsWorld::btMultiBodyDynamicsWorld(btDispatcher* dispatcher,btBroadphaseInterface* pairCache,btMultiBodyConstraintSolver* constraintSolver,btCollisionConfiguration* collisionConfiguration)
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:btDiscreteDynamicsWorld(dispatcher,pairCache,constraintSolver,collisionConfiguration)
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{
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//split impulse is not yet supported for Featherstone hierarchies
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getSolverInfo().m_splitImpulse = false;
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getSolverInfo().m_solverMode |=SOLVER_USE_2_FRICTION_DIRECTIONS;
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}
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btMultiBodyDynamicsWorld::~btMultiBodyDynamicsWorld ()
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{
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}
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void btMultiBodyDynamicsWorld::addMultiBody(btMultiBody* body, short group, short mask)
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{
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m_multiBodies.push_back(body);
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}
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void btMultiBodyDynamicsWorld::removeMultiBody(btMultiBody* body)
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{
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m_multiBodies.remove(body);
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}
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void btMultiBodyDynamicsWorld::calculateSimulationIslands()
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{
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BT_PROFILE("calculateSimulationIslands");
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getSimulationIslandManager()->updateActivationState(getCollisionWorld(),getCollisionWorld()->getDispatcher());
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{
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//merge islands based on speculative contact manifolds too
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for (int i=0;i<this->m_predictiveManifolds.size();i++)
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{
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btPersistentManifold* manifold = m_predictiveManifolds[i];
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const btCollisionObject* colObj0 = manifold->getBody0();
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const btCollisionObject* colObj1 = manifold->getBody1();
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if (((colObj0) && (!(colObj0)->isStaticOrKinematicObject())) &&
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((colObj1) && (!(colObj1)->isStaticOrKinematicObject())))
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{
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getSimulationIslandManager()->getUnionFind().unite((colObj0)->getIslandTag(),(colObj1)->getIslandTag());
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}
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}
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}
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{
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int i;
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int numConstraints = int(m_constraints.size());
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for (i=0;i< numConstraints ; i++ )
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{
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btTypedConstraint* constraint = m_constraints[i];
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if (constraint->isEnabled())
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{
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const btRigidBody* colObj0 = &constraint->getRigidBodyA();
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const btRigidBody* colObj1 = &constraint->getRigidBodyB();
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if (((colObj0) && (!(colObj0)->isStaticOrKinematicObject())) &&
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((colObj1) && (!(colObj1)->isStaticOrKinematicObject())))
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{
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getSimulationIslandManager()->getUnionFind().unite((colObj0)->getIslandTag(),(colObj1)->getIslandTag());
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}
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}
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}
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}
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//merge islands linked by Featherstone links
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for (int i=0;i<m_multiBodies.size();i++)
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{
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btMultiBody* body = m_multiBodies[i];
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if (body->getNumLinkColliders()>1)
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{
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btMultiBodyLinkCollider* prev = body->getLinkCollider(0);
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for (int b=1;b<body->getNumLinkColliders();b++)
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{
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btMultiBodyLinkCollider* cur = body->getLinkCollider(b);
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if (((cur) && (!(cur)->isStaticOrKinematicObject())) &&
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((prev) && (!(prev)->isStaticOrKinematicObject())))
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{
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int tagPrev = prev->getIslandTag();
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int tagCur = cur->getIslandTag();
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getSimulationIslandManager()->getUnionFind().unite(tagPrev, tagCur);
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}
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prev = cur;
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}
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}
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}
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//Store the island id in each body
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getSimulationIslandManager()->storeIslandActivationState(getCollisionWorld());
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}
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void btMultiBodyDynamicsWorld::updateActivationState(btScalar timeStep)
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{
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BT_PROFILE("btMultiBodyDynamicsWorld::updateActivationState");
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for ( int i=0;i<m_multiBodies.size();i++)
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{
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btMultiBody* body = m_multiBodies[i];
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if (body)
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{
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body->checkMotionAndSleepIfRequired(timeStep);
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if (!body->isAwake())
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{
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for (int b=0;b<body->getNumLinkColliders();b++)
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{
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btMultiBodyLinkCollider* col = body->getLinkCollider(b);
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if (col->getActivationState() == ACTIVE_TAG)
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{
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col->setActivationState( WANTS_DEACTIVATION);
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col->setDeactivationTime(0.f);
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}
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}
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} else
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{
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for (int b=0;b<body->getNumLinkColliders();b++)
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{
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btMultiBodyLinkCollider* col = body->getLinkCollider(b);
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if (col->getActivationState() != DISABLE_DEACTIVATION)
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col->setActivationState( ACTIVE_TAG );
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}
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}
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}
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}
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btDiscreteDynamicsWorld::updateActivationState(timeStep);
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}
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void btMultiBodyDynamicsWorld::solveConstraints(btContactSolverInfo& solverInfo)
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{
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btVector3 g = m_gravity;
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btAlignedObjectArray<btScalar> scratch_r;
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btAlignedObjectArray<btVector3> scratch_v;
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btAlignedObjectArray<btMatrix3x3> scratch_m;
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{
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BT_PROFILE("btMultiBody addForce and stepVelocities");
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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->getNumLinkColliders() && bod->getLinkCollider(0)->getActivationState()==ISLAND_SLEEPING)
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{
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isSleeping = true;
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}
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if (!isSleeping)
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{
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scratch_r.resize(bod->getNumLinks()+1);
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scratch_v.resize(bod->getNumLinks()+1);
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scratch_m.resize(bod->getNumLinks()+1);
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bod->clearForcesAndTorques();
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bod->addBaseForce(g * bod->getBaseMass());
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for (int j = 0; j < bod->getNumLinks(); ++j)
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{
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bod->addLinkForce(j, g * bod->getLinkMass(j));
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}
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bod->stepVelocities(solverInfo.m_timeStep, scratch_r, scratch_v, scratch_m);
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}
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}
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}
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btDiscreteDynamicsWorld::solveConstraints(solverInfo);
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}
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void btMultiBodyDynamicsWorld::integrateTransforms(btScalar timeStep)
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{
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btDiscreteDynamicsWorld::integrateTransforms(timeStep);
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{
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BT_PROFILE("btMultiBody stepPositions");
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//integrate and update the Featherstone hierarchies
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btAlignedObjectArray<btQuaternion> world_to_local;
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btAlignedObjectArray<btVector3> local_origin;
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for (int b=0;b<m_multiBodies.size();b++)
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{
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btMultiBody* bod = m_multiBodies[b];
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bool isSleeping = false;
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if (bod->getNumLinkColliders() && bod->getLinkCollider(0)->getActivationState()==ISLAND_SLEEPING)
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{
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isSleeping = true;
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}
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if (!isSleeping)
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{
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int nLinks = bod->getNumLinks();
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///base + num links
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world_to_local.resize(nLinks+1);
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local_origin.resize(nLinks+1);
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bod->stepPositions(timeStep);
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world_to_local[0] = bod->getWorldToBaseRot();
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local_origin[0] = bod->getBasePos();
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for (int k=0;k<bod->getNumLinks();k++)
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{
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const int parent = bod->getParent(k);
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world_to_local[k+1] = bod->getParentToLocalRot(k) * world_to_local[parent+1];
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local_origin[k+1] = local_origin[parent+1] + (quatRotate(world_to_local[k+1].inverse() , bod->getRVector(k)));
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}
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for (int m=0;m<bod->getNumLinkColliders();m++)
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{
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btMultiBodyLinkCollider* col = bod->getLinkCollider(m);
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int link = col->m_link;
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int index = link+1;
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float halfExtents[3]={7.5,0.05,4.5};
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btVector3 posr = local_origin[index];
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float pos[4]={posr.x(),posr.y(),posr.z(),1};
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float quat[4]={-world_to_local[index].x(),-world_to_local[index].y(),-world_to_local[index].z(),world_to_local[index].w()};
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//app->drawBox(halfExtents, pos,quat);
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btTransform tr;
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tr.setIdentity();
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tr.setOrigin(posr);
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tr.setRotation(btQuaternion(quat[0],quat[1],quat[2],quat[3]));
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col->setWorldTransform(tr);
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}
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} else
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{
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bod->clearVelocities();
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}
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}
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}
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}
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