Bullet Collision Detection & Physics Library
btContactConstraint.cpp
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1/*
2Bullet Continuous Collision Detection and Physics Library
3Copyright (c) 2003-2006 Erwin Coumans http://continuousphysics.com/Bullet/
4
5This software is provided 'as-is', without any express or implied warranty.
6In no event will the authors be held liable for any damages arising from the use of this software.
7Permission is granted to anyone to use this software for any purpose,
8including commercial applications, and to alter it and redistribute it freely,
9subject to the following restrictions:
10
111. 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.
122. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
133. This notice may not be removed or altered from any source distribution.
14*/
15
16
17#include "btContactConstraint.h"
20#include "btJacobianEntry.h"
21#include "btContactSolverInfo.h"
22#include "LinearMath/btMinMax.h"
24
25
26
29 m_contactManifold(*contactManifold)
30{
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32}
33
35{
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37}
38
40{
41 m_contactManifold = *contactManifold;
42}
43
45{
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47}
48
50{
51
52}
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55{
56
57}
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62
63#include "btContactConstraint.h"
66#include "btJacobianEntry.h"
67#include "btContactSolverInfo.h"
68#include "LinearMath/btMinMax.h"
70
71
72
73//response between two dynamic objects without friction and no restitution, assuming 0 penetration depth
75 btRigidBody* body1,
76 btCollisionObject* colObj2,
77 const btVector3& contactPositionWorld,
78 const btVector3& contactNormalOnB,
79 const btContactSolverInfo& solverInfo,
80 btScalar distance)
81{
82 btRigidBody* body2 = btRigidBody::upcast(colObj2);
83
84
85 const btVector3& normal = contactNormalOnB;
86
87 btVector3 rel_pos1 = contactPositionWorld - body1->getWorldTransform().getOrigin();
88 btVector3 rel_pos2 = contactPositionWorld - colObj2->getWorldTransform().getOrigin();
89
90 btVector3 vel1 = body1->getVelocityInLocalPoint(rel_pos1);
91 btVector3 vel2 = body2? body2->getVelocityInLocalPoint(rel_pos2) : btVector3(0,0,0);
92 btVector3 vel = vel1 - vel2;
93 btScalar rel_vel;
94 rel_vel = normal.dot(vel);
95
96 btScalar combinedRestitution = 0.f;
97 btScalar restitution = combinedRestitution* -rel_vel;
98
99 btScalar positionalError = solverInfo.m_erp *-distance /solverInfo.m_timeStep ;
100 btScalar velocityError = -(1.0f + restitution) * rel_vel;// * damping;
101 btScalar denom0 = body1->computeImpulseDenominator(contactPositionWorld,normal);
102 btScalar denom1 = body2? body2->computeImpulseDenominator(contactPositionWorld,normal) : 0.f;
103 btScalar relaxation = 1.f;
104 btScalar jacDiagABInv = relaxation/(denom0+denom1);
105
106 btScalar penetrationImpulse = positionalError * jacDiagABInv;
107 btScalar velocityImpulse = velocityError * jacDiagABInv;
108
109 btScalar normalImpulse = penetrationImpulse+velocityImpulse;
110 normalImpulse = 0.f > normalImpulse ? 0.f: normalImpulse;
111
112 body1->applyImpulse(normal*(normalImpulse), rel_pos1);
113 if (body2)
114 body2->applyImpulse(-normal*(normalImpulse), rel_pos2);
115
116 return normalImpulse;
117}
118
119
120//bilateral constraint between two dynamic objects
122 btRigidBody& body2, const btVector3& pos2,
123 btScalar distance, const btVector3& normal,btScalar& impulse ,btScalar timeStep)
124{
125 (void)timeStep;
126 (void)distance;
127
128
129 btScalar normalLenSqr = normal.length2();
130 btAssert(btFabs(normalLenSqr) < btScalar(1.1));
131 if (normalLenSqr > btScalar(1.1))
132 {
133 impulse = btScalar(0.);
134 return;
135 }
136 btVector3 rel_pos1 = pos1 - body1.getCenterOfMassPosition();
137 btVector3 rel_pos2 = pos2 - body2.getCenterOfMassPosition();
138 //this jacobian entry could be re-used for all iterations
139
140 btVector3 vel1 = body1.getVelocityInLocalPoint(rel_pos1);
141 btVector3 vel2 = body2.getVelocityInLocalPoint(rel_pos2);
142 btVector3 vel = vel1 - vel2;
143
144
147 rel_pos1,rel_pos2,normal,body1.getInvInertiaDiagLocal(),body1.getInvMass(),
148 body2.getInvInertiaDiagLocal(),body2.getInvMass());
149
150 btScalar jacDiagAB = jac.getDiagonal();
151 btScalar jacDiagABInv = btScalar(1.) / jacDiagAB;
152
153 btScalar rel_vel = jac.getRelativeVelocity(
154 body1.getLinearVelocity(),
156 body2.getLinearVelocity(),
158
159
160
161 rel_vel = normal.dot(vel);
162
163 //todo: move this into proper structure
164 btScalar contactDamping = btScalar(0.2);
165
166#ifdef ONLY_USE_LINEAR_MASS
167 btScalar massTerm = btScalar(1.) / (body1.getInvMass() + body2.getInvMass());
168 impulse = - contactDamping * rel_vel * massTerm;
169#else
170 btScalar velocityImpulse = -contactDamping * rel_vel * jacDiagABInv;
171 impulse = velocityImpulse;
172#endif
173}
174
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177
void resolveSingleBilateral(btRigidBody &body1, const btVector3 &pos1, btRigidBody &body2, const btVector3 &pos2, btScalar distance, const btVector3 &normal, btScalar &impulse, btScalar timeStep)
resolveSingleBilateral is an obsolete methods used for vehicle friction between two dynamic objects
btScalar resolveSingleCollision(btRigidBody *body1, btCollisionObject *colObj2, const btVector3 &contactPositionWorld, const btVector3 &contactNormalOnB, const btContactSolverInfo &solverInfo, btScalar distance)
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:292
btScalar btFabs(btScalar x)
Definition: btScalar.h:475
#define btAssert(x)
Definition: btScalar.h:131
@ CONTACT_CONSTRAINT_TYPE
btCollisionObject can be used to manage collision detection objects.
btTransform & getWorldTransform()
virtual void getInfo2(btConstraintInfo2 *info)
internal method used by the constraint solver, don't use them directly
virtual void buildJacobian()
obsolete methods
btPersistentManifold m_contactManifold
virtual void getInfo1(btConstraintInfo1 *info)
internal method used by the constraint solver, don't use them directly
btContactConstraint(btPersistentManifold *contactManifold, btRigidBody &rbA, btRigidBody &rbB)
void setContactManifold(btPersistentManifold *contactManifold)
Jacobian entry is an abstraction that allows to describe constraints it can be used in combination wi...
btScalar getDiagonal() const
btScalar getRelativeVelocity(const btVector3 &linvelA, const btVector3 &angvelA, const btVector3 &linvelB, const btVector3 &angvelB)
btMatrix3x3 transpose() const
Return the transpose of the matrix.
Definition: btMatrix3x3.h:958
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:63
btVector3 getVelocityInLocalPoint(const btVector3 &rel_pos) const
Definition: btRigidBody.h:382
btScalar getInvMass() const
Definition: btRigidBody.h:273
const btVector3 & getInvInertiaDiagLocal() const
Definition: btRigidBody.h:297
const btTransform & getCenterOfMassTransform() const
Definition: btRigidBody.h:359
void applyImpulse(const btVector3 &impulse, const btVector3 &rel_pos)
Definition: btRigidBody.h:334
const btVector3 & getAngularVelocity() const
Definition: btRigidBody.h:365
const btVector3 & getCenterOfMassPosition() const
Definition: btRigidBody.h:354
btScalar computeImpulseDenominator(const btVector3 &pos, const btVector3 &normal) const
Definition: btRigidBody.h:403
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:203
const btVector3 & getLinearVelocity() const
Definition: btRigidBody.h:362
btMatrix3x3 & getBasis()
Return the basis matrix for the rotation.
Definition: btTransform.h:112
btVector3 & getOrigin()
Return the origin vector translation.
Definition: btTransform.h:117
TypedConstraint is the baseclass for Bullet constraints and vehicles.
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:84
btScalar dot(const btVector3 &v) const
Return the dot product.
Definition: btVector3.h:235
btScalar length2() const
Return the length of the vector squared.
Definition: btVector3.h:257