Bullet Collision Detection & Physics Library: btContactConstraint.cpp Source File

Bullet Collision Detection & Physics Library

btContactConstraint.cpp
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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 #include "btContactConstraint.h"
17 #include "BulletDynamics/Dynamics/btRigidBody.h"
18 #include "LinearMath/btVector3.h"
19 #include "btJacobianEntry.h"
20 #include "btContactSolverInfo.h"
21 #include "LinearMath/btMinMax.h"
22 #include "BulletCollision/NarrowPhaseCollision/btManifoldPoint.h"
23
24 btContactConstraint::btContactConstraint(btPersistentManifold* contactManifold, btRigidBody& rbA, btRigidBody& rbB)
25 : btTypedConstraint(CONTACT_CONSTRAINT_TYPE, rbA, rbB),
26 m_contactManifold(*contactManifold)
27 {
28 }
29
30 btContactConstraint::~btContactConstraint()
31 {
32 }
33
34 void btContactConstraint::setContactManifold(btPersistentManifold* contactManifold)
35 {
36 m_contactManifold = *contactManifold;
37 }
38
39 void btContactConstraint::getInfo1(btConstraintInfo1* info)
40 {
41 }
42
43 void btContactConstraint::getInfo2(btConstraintInfo2* info)
44 {
45 }
46
47 void btContactConstraint::buildJacobian()
48 {
49 }
50
51 #include "btContactConstraint.h"
52 #include "BulletDynamics/Dynamics/btRigidBody.h"
53 #include "LinearMath/btVector3.h"
54 #include "btJacobianEntry.h"
55 #include "btContactSolverInfo.h"
56 #include "LinearMath/btMinMax.h"
57 #include "BulletCollision/NarrowPhaseCollision/btManifoldPoint.h"
58
59 //response between two dynamic objects without friction and no restitution, assuming 0 penetration depth
60 btScalar resolveSingleCollision(
61 btRigidBody* body1,
62 btCollisionObject* colObj2,
63 const btVector3& contactPositionWorld,
64 const btVector3& contactNormalOnB,
65 const btContactSolverInfo& solverInfo,
66 btScalar distance)
67 {
68 btRigidBody* body2 = btRigidBody::upcast(colObj2);
69
70 const btVector3& normal = contactNormalOnB;
71
72 btVector3 rel_pos1 = contactPositionWorld - body1->getWorldTransform().getOrigin();
73 btVector3 rel_pos2 = contactPositionWorld - colObj2->getWorldTransform().getOrigin();
74
75 btVector3 vel1 = body1->getVelocityInLocalPoint(rel_pos1);
76 btVector3 vel2 = body2 ? body2->getVelocityInLocalPoint(rel_pos2) : btVector3(0, 0, 0);
77 btVector3 vel = vel1 - vel2;
78 btScalar rel_vel;
79 rel_vel = normal.dot(vel);
80
81 btScalar combinedRestitution = 0.f;
82 btScalar restitution = combinedRestitution * -rel_vel;
83
84 btScalar positionalError = solverInfo.m_erp * -distance / solverInfo.m_timeStep;
85 btScalar velocityError = -(1.0f + restitution) * rel_vel; // * damping;
86 btScalar denom0 = body1->computeImpulseDenominator(contactPositionWorld, normal);
87 btScalar denom1 = body2 ? body2->computeImpulseDenominator(contactPositionWorld, normal) : 0.f;
88 btScalar relaxation = 1.f;
89 btScalar jacDiagABInv = relaxation / (denom0 + denom1);
90
91 btScalar penetrationImpulse = positionalError * jacDiagABInv;
92 btScalar velocityImpulse = velocityError * jacDiagABInv;
93
94 btScalar normalImpulse = penetrationImpulse + velocityImpulse;
95 normalImpulse = 0.f > normalImpulse ? 0.f : normalImpulse;
96
97 body1->applyImpulse(normal * (normalImpulse), rel_pos1);
98 if (body2)
99 body2->applyImpulse(-normal * (normalImpulse), rel_pos2);
100
101 return normalImpulse;
102 }
103
104 //bilateral constraint between two dynamic objects
105 void resolveSingleBilateral(btRigidBody& body1, const btVector3& pos1,
106 btRigidBody& body2, const btVector3& pos2,
107 btScalar distance, const btVector3& normal, btScalar& impulse, btScalar timeStep)
108 {
109 (void)timeStep;
110 (void)distance;
111
112 btScalar normalLenSqr = normal.length2();
113 btAssert(btFabs(normalLenSqr) < btScalar(1.1));
114 if (normalLenSqr > btScalar(1.1))
115 {
116 impulse = btScalar(0.);
117 return;
118 }
119 btVector3 rel_pos1 = pos1 - body1.getCenterOfMassPosition();
120 btVector3 rel_pos2 = pos2 - body2.getCenterOfMassPosition();
121 //this jacobian entry could be re-used for all iterations
122
123 btVector3 vel1 = body1.getVelocityInLocalPoint(rel_pos1);
124 btVector3 vel2 = body2.getVelocityInLocalPoint(rel_pos2);
125 btVector3 vel = vel1 - vel2;
126
127 btJacobianEntry jac(body1.getCenterOfMassTransform().getBasis().transpose(),
128 body2.getCenterOfMassTransform().getBasis().transpose(),
129 rel_pos1, rel_pos2, normal, body1.getInvInertiaDiagLocal(), body1.getInvMass(),
130 body2.getInvInertiaDiagLocal(), body2.getInvMass());
131
132 btScalar jacDiagAB = jac.getDiagonal();
133 btScalar jacDiagABInv = btScalar(1.) / jacDiagAB;
134
135 btScalar rel_vel = jac.getRelativeVelocity(
136 body1.getLinearVelocity(),
137 body1.getCenterOfMassTransform().getBasis().transpose() * body1.getAngularVelocity(),
138 body2.getLinearVelocity(),
139 body2.getCenterOfMassTransform().getBasis().transpose() * body2.getAngularVelocity());
140
141 rel_vel = normal.dot(vel);
142
143 //todo: move this into proper structure
144 btScalar contactDamping = btScalar(0.2);
145
146 #ifdef ONLY_USE_LINEAR_MASS
147 btScalar massTerm = btScalar(1.) / (body1.getInvMass() + body2.getInvMass());
148 impulse = -contactDamping * rel_vel * massTerm;
149 #else
150 btScalar velocityImpulse = -contactDamping * rel_vel * jacDiagABInv;
151 impulse = velocityImpulse;
152 #endif
153 }
btRigidBody::upcast
static const btRigidBody * upcast(const btCollisionObject *colObj)
to keep collision detection and dynamics separate we don&#39;t store a rigidbody pointer but a rigidbody ...
Definition: btRigidBody.h:189
btContactConstraint::buildJacobian
virtual void buildJacobian()
obsolete methods
Definition: btContactConstraint.cpp:47
btPersistentManifold
btPersistentManifold is a contact point cache, it stays persistent as long as objects are overlapping...
Definition: btPersistentManifold.h:63
btRigidBody::computeImpulseDenominator
btScalar computeImpulseDenominator(const btVector3 &pos, const btVector3 &normal) const
Definition: btRigidBody.h:390
btRigidBody::getAngularVelocity
const btVector3 & getAngularVelocity() const
Definition: btRigidBody.h:357
btContactSolverInfoData::m_erp
btScalar m_erp
Definition: btContactSolverInfo.h:46
btJacobianEntry
Jacobian entry is an abstraction that allows to describe constraints it can be used in combination wi...
Definition: btJacobianEntry.h:29
btTypedConstraint::btConstraintInfo2
Definition: btTypedConstraint.h:120
btVector3.h
btRigidBody::getCenterOfMassTransform
const btTransform & getCenterOfMassTransform() const
Definition: btRigidBody.h:349
btVector3::length2
btScalar length2() const
Return the length of the vector squared.
Definition: btVector3.h:251
btContactConstraint::getInfo2
virtual void getInfo2(btConstraintInfo2 *info)
internal method used by the constraint solver, don&#39;t use them directly
Definition: btContactConstraint.cpp:43
btAssert
#define btAssert(x)
Definition: btScalar.h:133
CONTACT_CONSTRAINT_TYPE
Definition: btTypedConstraint.h:41
btContactConstraint.h
btRigidBody.h
btContactConstraint::btContactConstraint
btContactConstraint(btPersistentManifold *contactManifold, btRigidBody &rbA, btRigidBody &rbB)
Definition: btContactConstraint.cpp:24
btMatrix3x3::transpose
btMatrix3x3 transpose() const
Return the transpose of the matrix.
Definition: btMatrix3x3.h:1026
btContactConstraint::getInfo1
virtual void getInfo1(btConstraintInfo1 *info)
internal method used by the constraint solver, don&#39;t use them directly
Definition: btContactConstraint.cpp:39
btCollisionObject::getWorldTransform
btTransform & getWorldTransform()
Definition: btCollisionObject.h:365
btRigidBody::getInvInertiaDiagLocal
const btVector3 & getInvInertiaDiagLocal() const
Definition: btRigidBody.h:286
btTransform::getOrigin
btVector3 & getOrigin()
Return the origin vector translation.
Definition: btTransform.h:113
btRigidBody::getLinearVelocity
const btVector3 & getLinearVelocity() const
Definition: btRigidBody.h:353
resolveSingleBilateral
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 ...
Definition: btContactConstraint.cpp:105
btRigidBody::getInvMass
btScalar getInvMass() const
Definition: btRigidBody.h:261
btVector3::dot
btScalar dot(const btVector3 &v) const
Return the dot product.
Definition: btVector3.h:229
btCollisionObject
btCollisionObject can be used to manage collision detection objects.
Definition: btCollisionObject.h:48
btTransform::getBasis
btMatrix3x3 & getBasis()
Return the basis matrix for the rotation.
Definition: btTransform.h:108
btRigidBody
The btRigidBody is the main class for rigid body objects.
Definition: btRigidBody.h:59
btContactConstraint::setContactManifold
void setContactManifold(btPersistentManifold *contactManifold)
Definition: btContactConstraint.cpp:34
btMinMax.h
btJacobianEntry.h
btVector3
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:80
btRigidBody::getVelocityInLocalPoint
btVector3 getVelocityInLocalPoint(const btVector3 &rel_pos) const
Definition: btRigidBody.h:374
btContactConstraint::~btContactConstraint
virtual ~btContactConstraint()
Definition: btContactConstraint.cpp:30
btContactSolverInfo
Definition: btContactSolverInfo.h:69
btRigidBody::getCenterOfMassPosition
const btVector3 & getCenterOfMassPosition() const
Definition: btRigidBody.h:343
btJacobianEntry::getDiagonal
btScalar getDiagonal() const
Definition: btJacobianEntry.h:104
btTypedConstraint
TypedConstraint is the baseclass for Bullet constraints and vehicles.
Definition: btTypedConstraint.h:74
resolveSingleCollision
btScalar resolveSingleCollision(btRigidBody *body1, btCollisionObject *colObj2, const btVector3 &contactPositionWorld, const btVector3 &contactNormalOnB, const btContactSolverInfo &solverInfo, btScalar distance)
Definition: btContactConstraint.cpp:60
btRigidBody::applyImpulse
void applyImpulse(const btVector3 &impulse, const btVector3 &rel_pos)
Definition: btRigidBody.h:323
btContactConstraint::m_contactManifold
btPersistentManifold m_contactManifold
Definition: btContactConstraint.h:29
btContactSolverInfoData::m_timeStep
btScalar m_timeStep
Definition: btContactSolverInfo.h:41
btTypedConstraint::btConstraintInfo1
Definition: btTypedConstraint.h:113
btManifoldPoint.h
btScalar
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:294
btContactSolverInfo.h
btFabs
btScalar btFabs(btScalar x)
Definition: btScalar.h:477