Bullet Collision Detection & Physics Library
btDeformableMultiBodyConstraintSolver.cpp
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1 /*
2  Written by Xuchen Han <xuchenhan2015@u.northwestern.edu>
3 
4  Bullet Continuous Collision Detection and Physics Library
5  Copyright (c) 2019 Google Inc. http://bulletphysics.org
6  This software is provided 'as-is', without any express or implied warranty.
7  In no event will the authors be held liable for any damages arising from the use of this software.
8  Permission is granted to anyone to use this software for any purpose,
9  including commercial applications, and to alter it and redistribute it freely,
10  subject to the following restrictions:
11  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.
12  2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
13  3. This notice may not be removed or altered from any source distribution.
14  */
15 
17 #include <iostream>
18 // override the iterations method to include deformable/multibody contact
19 btScalar btDeformableMultiBodyConstraintSolver::solveDeformableGroupIterations(btCollisionObject** bodies, int numBodies, btCollisionObject** deformableBodies, int numDeformableBodies, btPersistentManifold** manifoldPtr, int numManifolds, btTypedConstraint** constraints, int numConstraints, const btContactSolverInfo& infoGlobal, btIDebugDraw* debugDrawer)
20 {
21  {
23  solveGroupCacheFriendlySplitImpulseIterations(bodies, numBodies, deformableBodies, numDeformableBodies, manifoldPtr, numManifolds, constraints, numConstraints, infoGlobal, debugDrawer);
24 
26  for (int iteration = 0; iteration < maxIterations; iteration++)
27  {
28  // rigid bodies are solved using solver body velocity, but rigid/deformable contact directly uses the velocity of the actual rigid body. So we have to do the following: Solve one iteration of the rigid/rigid contact, get the updated velocity in the solver body and update the velocity of the underlying rigid body. Then solve the rigid/deformable contact. Finally, grab the (once again) updated rigid velocity and update the velocity of the wrapping solver body
29 
30  // solve rigid/rigid in solver body
31  m_leastSquaresResidual = solveSingleIteration(iteration, bodies, numBodies, manifoldPtr, numManifolds, constraints, numConstraints, infoGlobal, debugDrawer);
32  // solver body velocity -> rigid body velocity
33  solverBodyWriteBack(infoGlobal);
34  btScalar deformableResidual = m_deformableSolver->solveContactConstraints(deformableBodies, numDeformableBodies, infoGlobal);
35  // update rigid body velocity in rigid/deformable contact
37  // solver body velocity <- rigid body velocity
38  writeToSolverBody(bodies, numBodies, infoGlobal);
39 
40  if (m_leastSquaresResidual <= infoGlobal.m_leastSquaresResidualThreshold || (iteration >= (maxIterations - 1)))
41  {
42 #ifdef VERBOSE_RESIDUAL_PRINTF
43  if (iteration >= (maxIterations - 1))
44  printf("residual = %f at iteration #%d\n", m_leastSquaresResidual, iteration);
45 #endif
47  m_analyticsData.m_numIterationsUsed = iteration + 1;
49  if (numBodies > 0)
51  m_analyticsData.m_numBodies = numBodies;
54  break;
55  }
56  }
57  }
58  return 0.f;
59 }
60 
61 void btDeformableMultiBodyConstraintSolver::solveDeformableBodyGroup(btCollisionObject** bodies, int numBodies, btCollisionObject** deformableBodies, int numDeformableBodies, btPersistentManifold** manifold, int numManifolds, btTypedConstraint** constraints, int numConstraints, btMultiBodyConstraint** multiBodyConstraints, int numMultiBodyConstraints, const btContactSolverInfo& info, btIDebugDraw* debugDrawer, btDispatcher* dispatcher)
62 {
63  m_tmpMultiBodyConstraints = multiBodyConstraints;
64  m_tmpNumMultiBodyConstraints = numMultiBodyConstraints;
65 
66  // inherited from MultiBodyConstraintSolver
67  solveGroupCacheFriendlySetup(bodies, numBodies, manifold, numManifolds, constraints, numConstraints, info, debugDrawer);
68 
69  // overriden
70  solveDeformableGroupIterations(bodies, numBodies, deformableBodies, numDeformableBodies, manifold, numManifolds, constraints, numConstraints, info, debugDrawer);
71 
72  // inherited from MultiBodyConstraintSolver
73  solveGroupCacheFriendlyFinish(bodies, numBodies, info);
74 
77 }
78 
80 {
81  for (int i = 0; i < numBodies; i++)
82  {
83  int bodyId = getOrInitSolverBody(*bodies[i], infoGlobal.m_timeStep);
84 
85  btRigidBody* body = btRigidBody::upcast(bodies[i]);
86  if (body && body->getInvMass())
87  {
88  btSolverBody& solverBody = m_tmpSolverBodyPool[bodyId];
89  solverBody.m_linearVelocity = body->getLinearVelocity() - solverBody.m_deltaLinearVelocity;
90  solverBody.m_angularVelocity = body->getAngularVelocity() - solverBody.m_deltaAngularVelocity;
91  }
92  }
93 }
94 
96 {
97  for (int i = 0; i < m_tmpSolverBodyPool.size(); i++)
98  {
99  btRigidBody* body = m_tmpSolverBodyPool[i].m_originalBody;
100  if (body)
101  {
102  m_tmpSolverBodyPool[i].m_originalBody->setLinearVelocity(m_tmpSolverBodyPool[i].m_linearVelocity + m_tmpSolverBodyPool[i].m_deltaLinearVelocity);
103  m_tmpSolverBodyPool[i].m_originalBody->setAngularVelocity(m_tmpSolverBodyPool[i].m_angularVelocity + m_tmpSolverBodyPool[i].m_deltaAngularVelocity);
104  }
105  }
106 }
107 
108 void btDeformableMultiBodyConstraintSolver::solveGroupCacheFriendlySplitImpulseIterations(btCollisionObject** bodies, int numBodies, btCollisionObject** deformableBodies, int numDeformableBodies, btPersistentManifold** manifoldPtr, int numManifolds, btTypedConstraint** constraints, int numConstraints, const btContactSolverInfo& infoGlobal, btIDebugDraw* debugDrawer)
109 {
110  BT_PROFILE("solveGroupCacheFriendlySplitImpulseIterations");
111  int iteration;
112  if (infoGlobal.m_splitImpulse)
113  {
114  {
115  for (iteration = 0; iteration < infoGlobal.m_numIterations; iteration++)
116  {
117  btScalar leastSquaresResidual = 0.f;
118  {
119  int numPoolConstraints = m_tmpSolverContactConstraintPool.size();
120  int j;
121  for (j = 0; j < numPoolConstraints; j++)
122  {
124 
125  btScalar residual = resolveSplitPenetrationImpulse(m_tmpSolverBodyPool[solveManifold.m_solverBodyIdA], m_tmpSolverBodyPool[solveManifold.m_solverBodyIdB], solveManifold);
126  leastSquaresResidual = btMax(leastSquaresResidual, residual * residual);
127  }
128  // solve the position correction between deformable and rigid/multibody
129  // btScalar residual = m_deformableSolver->solveSplitImpulse(infoGlobal);
130  btScalar residual = m_deformableSolver->m_objective->m_projection.solveSplitImpulse(deformableBodies, numDeformableBodies, infoGlobal);
131  leastSquaresResidual = btMax(leastSquaresResidual, residual * residual);
132  }
133  if (leastSquaresResidual <= infoGlobal.m_leastSquaresResidualThreshold || iteration >= (infoGlobal.m_numIterations - 1))
134  {
135 #ifdef VERBOSE_RESIDUAL_PRINTF
136  if (iteration >= (infoGlobal.m_numIterations - 1))
137  printf("split impulse residual = %f at iteration #%d\n", leastSquaresResidual, iteration);
138 #endif
139  break;
140  }
141  }
142  }
143  }
144 }
const T & btMax(const T &a, const T &b)
Definition: btMinMax.h:27
#define BT_PROFILE(name)
Definition: btQuickprof.h:198
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:314
int size() const
return the number of elements in the array
btCollisionObject can be used to manage collision detection objects.
int getCompanionId() const
btDeformableBackwardEulerObjective * m_objective
virtual btScalar solveContactConstraints(btCollisionObject **deformableBodies, int numDeformableBodies, const btContactSolverInfo &infoGlobal)
btScalar solveSplitImpulse(btCollisionObject **deformableBodies, int numDeformableBodies, const btContactSolverInfo &infoGlobal)
void writeToSolverBody(btCollisionObject **bodies, int numBodies, const btContactSolverInfo &infoGlobal)
virtual void solveDeformableBodyGroup(btCollisionObject **bodies, int numBodies, btCollisionObject **deformableBodies, int numDeformableBodies, btPersistentManifold **manifold, int numManifolds, btTypedConstraint **constraints, int numConstraints, btMultiBodyConstraint **multiBodyConstraints, int numMultiBodyConstraints, const btContactSolverInfo &info, btIDebugDraw *debugDrawer, btDispatcher *dispatcher)
virtual void solveGroupCacheFriendlySplitImpulseIterations(btCollisionObject **bodies, int numBodies, btCollisionObject **deformableBodies, int numDeformableBodies, btPersistentManifold **manifoldPtr, int numManifolds, btTypedConstraint **constraints, int numConstraints, const btContactSolverInfo &infoGlobal, btIDebugDraw *debugDrawer)
virtual btScalar solveDeformableGroupIterations(btCollisionObject **bodies, int numBodies, btCollisionObject **deformableBodies, int numDeformableBodies, btPersistentManifold **manifoldPtr, int numManifolds, btTypedConstraint **constraints, int numConstraints, const btContactSolverInfo &infoGlobal, btIDebugDraw *debugDrawer)
void solverBodyWriteBack(const btContactSolverInfo &infoGlobal)
The btDispatcher interface class can be used in combination with broadphase to dispatch calculations ...
Definition: btDispatcher.h:77
The btIDebugDraw interface class allows hooking up a debug renderer to visually debug simulations.
Definition: btIDebugDraw.h:27
btMultiBodyConstraint ** m_tmpMultiBodyConstraints
virtual btScalar solveGroupCacheFriendlyFinish(btCollisionObject **bodies, int numBodies, const btContactSolverInfo &infoGlobal)
virtual btScalar solveGroupCacheFriendlySetup(btCollisionObject **bodies, int numBodies, btPersistentManifold **manifoldPtr, int numManifolds, btTypedConstraint **constraints, int numConstraints, const btContactSolverInfo &infoGlobal, btIDebugDraw *debugDrawer)
virtual btScalar solveSingleIteration(int iteration, btCollisionObject **bodies, int numBodies, btPersistentManifold **manifoldPtr, int numManifolds, btTypedConstraint **constraints, int numConstraints, const btContactSolverInfo &infoGlobal, btIDebugDraw *debugDrawer)
btPersistentManifold is a contact point cache, it stays persistent as long as objects are overlapping...
The btRigidBody is the main class for rigid body objects.
Definition: btRigidBody.h:60
const btVector3 & getAngularVelocity() const
Definition: btRigidBody.h:437
btScalar getInvMass() const
Definition: btRigidBody.h:263
static const btRigidBody * upcast(const btCollisionObject *colObj)
to keep collision detection and dynamics separate we don't store a rigidbody pointer but a rigidbody ...
Definition: btRigidBody.h:189
const btVector3 & getLinearVelocity() const
Definition: btRigidBody.h:433
btAlignedObjectArray< btSolverBody > m_tmpSolverBodyPool
int getOrInitSolverBody(btCollisionObject &body, btScalar timeStep)
btScalar resolveSplitPenetrationImpulse(btSolverBody &bodyA, btSolverBody &bodyB, const btSolverConstraint &contactConstraint)
TypedConstraint is the baseclass for Bullet constraints and vehicles.
The btSolverBody is an internal datastructure for the constraint solver. Only necessary data is packe...
Definition: btSolverBody.h:105
btVector3 m_angularVelocity
Definition: btSolverBody.h:116
btVector3 m_deltaLinearVelocity
Definition: btSolverBody.h:108
btVector3 m_deltaAngularVelocity
Definition: btSolverBody.h:109
btVector3 m_linearVelocity
Definition: btSolverBody.h:115
1D constraint along a normal axis between bodyA and bodyB. It can be combined to solve contact and fr...