1 /*
2 Bullet Continuous Collision Detection and Physics Library
3 Copyright (c) 2003-2006 Erwin Coumans http://continuousphysics.com/Bullet/
4
5 This software is provided 'as-is', without any express or implied warranty.
6 In no event will the authors be held liable for any damages arising from the use of this software.
7 Permission is granted to anyone to use this software for any purpose,
8 including commercial applications, and to alter it and redistribute it freely,
9 subject to the following restrictions:
10
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
16
17 #include "btContactConstraint.h"
18 #include "BulletDynamics/Dynamics/btRigidBody.h"
19 #include "LinearMath/btVector3.h"
20 #include "btJacobianEntry.h"
21 #include "btContactSolverInfo.h"
22 #include "LinearMath/btMinMax.h"
23 #include "BulletCollision/NarrowPhaseCollision/btManifoldPoint.h"
24
25
26
btContactConstraint(btPersistentManifold * contactManifold,btRigidBody & rbA,btRigidBody & rbB)27 btContactConstraint::btContactConstraint(btPersistentManifold* contactManifold,btRigidBody& rbA,btRigidBody& rbB)
28 :btTypedConstraint(CONTACT_CONSTRAINT_TYPE,rbA,rbB),
29 m_contactManifold(*contactManifold)
30 {
31
32 }
33
~btContactConstraint()34 btContactConstraint::~btContactConstraint()
35 {
36
37 }
38
setContactManifold(btPersistentManifold * contactManifold)39 void btContactConstraint::setContactManifold(btPersistentManifold* contactManifold)
40 {
41 m_contactManifold = *contactManifold;
42 }
43
getInfo1(btConstraintInfo1 * info)44 void btContactConstraint::getInfo1 (btConstraintInfo1* info)
45 {
46
47 }
48
getInfo2(btConstraintInfo2 * info)49 void btContactConstraint::getInfo2 (btConstraintInfo2* info)
50 {
51
52 }
53
buildJacobian()54 void btContactConstraint::buildJacobian()
55 {
56
57 }
58
59
60
61
62
63 #include "btContactConstraint.h"
64 #include "BulletDynamics/Dynamics/btRigidBody.h"
65 #include "LinearMath/btVector3.h"
66 #include "btJacobianEntry.h"
67 #include "btContactSolverInfo.h"
68 #include "LinearMath/btMinMax.h"
69 #include "BulletCollision/NarrowPhaseCollision/btManifoldPoint.h"
70
71
72
73 //response between two dynamic objects without friction and no restitution, assuming 0 penetration depth
resolveSingleCollision(btRigidBody * body1,btCollisionObject * colObj2,const btVector3 & contactPositionWorld,const btVector3 & contactNormalOnB,const btContactSolverInfo & solverInfo,btScalar distance)74 btScalar resolveSingleCollision(
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
resolveSingleBilateral(btRigidBody & body1,const btVector3 & pos1,btRigidBody & body2,const btVector3 & pos2,btScalar distance,const btVector3 & normal,btScalar & impulse,btScalar timeStep)121 void resolveSingleBilateral(btRigidBody& body1, const btVector3& pos1,
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
145 btJacobianEntry jac(body1.getCenterOfMassTransform().getBasis().transpose(),
146 body2.getCenterOfMassTransform().getBasis().transpose(),
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(),
155 body1.getCenterOfMassTransform().getBasis().transpose() * body1.getAngularVelocity(),
156 body2.getLinearVelocity(),
157 body2.getCenterOfMassTransform().getBasis().transpose() * body2.getAngularVelocity());
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
175
176
177
178