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

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btMultiBodyGearConstraint.cpp
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1/*
2Bullet Continuous Collision Detection and Physics Library
3Copyright (c) 2013 Erwin Coumans http://bulletphysics.org
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
17
18#include "btMultiBodyGearConstraint.h"
19#include "btMultiBody.h"
20#include "btMultiBodyLinkCollider.h"
21#include "BulletCollision/CollisionDispatch/btCollisionObject.h"
22
23btMultiBodyGearConstraint::btMultiBodyGearConstraint(btMultiBody* bodyA, int linkA, btMultiBody* bodyB, int linkB, const btVector3& pivotInA, const btVector3& pivotInB, const btMatrix3x3& frameInA, const btMatrix3x3& frameInB)
24 : btMultiBodyConstraint(bodyA, bodyB, linkA, linkB, 1, false, MULTIBODY_CONSTRAINT_GEAR),
25 m_gearRatio(1),
26 m_gearAuxLink(-1),
27 m_erp(0),
28 m_relativePositionTarget(0)
29{
30}
31
32 void btMultiBodyGearConstraint::finalizeMultiDof()
33{
34 allocateJacobiansMultiDof();
35
36 m_numDofsFinalized = m_jacSizeBoth;
37}
38
39btMultiBodyGearConstraint::~btMultiBodyGearConstraint()
40{
41}
42
43 int btMultiBodyGearConstraint::getIslandIdA() const
44{
45 if (m_bodyA)
46 {
47 if (m_linkA < 0)
48 {
49 btMultiBodyLinkCollider* col = m_bodyA->getBaseCollider();
50 if (col)
51 return col->getIslandTag();
52 }
53 else
54 {
55 if (m_bodyA->getLink(m_linkA).m_collider)
56 return m_bodyA->getLink(m_linkA).m_collider->getIslandTag();
57 }
58 }
59 return -1;
60}
61
62 int btMultiBodyGearConstraint::getIslandIdB() const
63{
64 if (m_bodyB)
65 {
66 if (m_linkB < 0)
67 {
68 btMultiBodyLinkCollider* col = m_bodyB->getBaseCollider();
69 if (col)
70 return col->getIslandTag();
71 }
72 else
73 {
74 if (m_bodyB->getLink(m_linkB).m_collider)
75 return m_bodyB->getLink(m_linkB).m_collider->getIslandTag();
76 }
77 }
78 return -1;
79}
80
81 void btMultiBodyGearConstraint::createConstraintRows(btMultiBodyConstraintArray& constraintRows,
82 btMultiBodyJacobianData& data,
83 const btContactSolverInfo& infoGlobal)
84{
85 // only positions need to be updated -- data.m_jacobians and force
86 // directions were set in the ctor and never change.
87
88 if (m_numDofsFinalized != m_jacSizeBoth)
89 {
90 finalizeMultiDof();
91 }
92
93 //don't crash
94 if (m_numDofsFinalized != m_jacSizeBoth)
95 return;
96
97 if (m_maxAppliedImpulse == 0.f)
98 return;
99
100 // note: we rely on the fact that data.m_jacobians are
101 // always initialized to zero by the Constraint ctor
102 int linkDoF = 0;
103 unsigned int offsetA = 6 + (m_bodyA->getLink(m_linkA).m_dofOffset + linkDoF);
104 unsigned int offsetB = 6 + (m_bodyB->getLink(m_linkB).m_dofOffset + linkDoF);
105
106 // row 0: the lower bound
107 jacobianA(0)[offsetA] = 1;
108 jacobianB(0)[offsetB] = m_gearRatio;
109
110 btScalar posError = 0;
111 const btVector3 dummy(0, 0, 0);
112
113 btScalar kp = 1;
114 btScalar kd = 1;
115 int numRows = getNumRows();
116
117 for (int row = 0; row < numRows; row++)
118 {
119 btMultiBodySolverConstraint& constraintRow = constraintRows.expandNonInitializing();
120
121 int dof = 0;
122 btScalar currentPosition = m_bodyA->getJointPosMultiDof(m_linkA)[dof];
123 btScalar currentVelocity = m_bodyA->getJointVelMultiDof(m_linkA)[dof];
124 btScalar auxVel = 0;
125
126 if (m_gearAuxLink >= 0)
127 {
128 auxVel = m_bodyA->getJointVelMultiDof(m_gearAuxLink)[dof];
129 }
130 currentVelocity += auxVel;
131 if (m_erp != 0)
132 {
133 btScalar currentPositionA = m_bodyA->getJointPosMultiDof(m_linkA)[dof];
134 if (m_gearAuxLink >= 0)
135 {
136 currentPositionA -= m_bodyA->getJointPosMultiDof(m_gearAuxLink)[dof];
137 }
138 btScalar currentPositionB = m_gearRatio * m_bodyA->getJointPosMultiDof(m_linkB)[dof];
139 btScalar diff = currentPositionB + currentPositionA;
140 btScalar desiredPositionDiff = this->m_relativePositionTarget;
141 posError = -m_erp * (desiredPositionDiff - diff);
142 }
143
144 btScalar desiredRelativeVelocity = auxVel;
145
146 fillMultiBodyConstraint(constraintRow, data, jacobianA(row), jacobianB(row), dummy, dummy, dummy, dummy, posError, infoGlobal, -m_maxAppliedImpulse, m_maxAppliedImpulse, false, 1, false, desiredRelativeVelocity);
147
148 constraintRow.m_orgConstraint = this;
149 constraintRow.m_orgDofIndex = row;
150 {
151 //expect either prismatic or revolute joint type for now
152 btAssert((m_bodyA->getLink(m_linkA).m_jointType == btMultibodyLink::eRevolute) || (m_bodyA->getLink(m_linkA).m_jointType == btMultibodyLink::ePrismatic));
153 switch (m_bodyA->getLink(m_linkA).m_jointType)
154 {
155 case btMultibodyLink::eRevolute:
156 {
157 constraintRow.m_contactNormal1.setZero();
158 constraintRow.m_contactNormal2.setZero();
159 btVector3 revoluteAxisInWorld = quatRotate(m_bodyA->getLink(m_linkA).m_cachedWorldTransform.getRotation(), m_bodyA->getLink(m_linkA).m_axes[0].m_topVec);
160 constraintRow.m_relpos1CrossNormal = revoluteAxisInWorld;
161 constraintRow.m_relpos2CrossNormal = -revoluteAxisInWorld;
162
163 break;
164 }
165 case btMultibodyLink::ePrismatic:
166 {
167 btVector3 prismaticAxisInWorld = quatRotate(m_bodyA->getLink(m_linkA).m_cachedWorldTransform.getRotation(), m_bodyA->getLink(m_linkA).m_axes[0].m_bottomVec);
168 constraintRow.m_contactNormal1 = prismaticAxisInWorld;
169 constraintRow.m_contactNormal2 = -prismaticAxisInWorld;
170 constraintRow.m_relpos1CrossNormal.setZero();
171 constraintRow.m_relpos2CrossNormal.setZero();
172 break;
173 }
174 default:
175 {
176 btAssert(0);
177 }
178 };
179 }
180 }
181}
btCollisionObject.h
MULTIBODY_CONSTRAINT_GEAR
@ MULTIBODY_CONSTRAINT_GEAR
Definition: btMultiBodyConstraint.h:29
btMultiBodyGearConstraint.h
btMultiBodyLinkCollider.h
btMultiBody.h
quatRotate
btVector3 quatRotate(const btQuaternion &rotation, const btVector3 &v)
Definition: btQuaternion.h:926
btScalar
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:314
btAssert
#define btAssert(x)
Definition: btScalar.h:153
btAlignedObjectArray< btMultiBodySolverConstraint >
btAlignedObjectArray::expandNonInitializing
T & expandNonInitializing()
Definition: btAlignedObjectArray.h:230
btCollisionObject::getIslandTag
int getIslandTag() const
Definition: btCollisionObject.h:448
btMatrix3x3
The btMatrix3x3 class implements a 3x3 rotation matrix, to perform linear algebra in combination with...
Definition: btMatrix3x3.h:50
btMultiBodyConstraint
Definition: btMultiBodyConstraint.h:57
btMultiBodyConstraint::m_bodyB
btMultiBody * m_bodyB
Definition: btMultiBodyConstraint.h:60
btMultiBodyConstraint::jacobianA
btScalar * jacobianA(int row)
Definition: btMultiBodyConstraint.h:181
btMultiBodyConstraint::m_maxAppliedImpulse
btScalar m_maxAppliedImpulse
Definition: btMultiBodyConstraint.h:73
btMultiBodyConstraint::jacobianB
btScalar * jacobianB(int row)
Definition: btMultiBodyConstraint.h:189
btMultiBodyConstraint::m_numDofsFinalized
int m_numDofsFinalized
Definition: btMultiBodyConstraint.h:72
btMultiBodyConstraint::allocateJacobiansMultiDof
void allocateJacobiansMultiDof()
Definition: btMultiBodyConstraint.cpp:35
btMultiBodyConstraint::fillMultiBodyConstraint
btScalar fillMultiBodyConstraint(btMultiBodySolverConstraint &solverConstraint, btMultiBodyJacobianData &data, btScalar *jacOrgA, btScalar *jacOrgB, const btVector3 &constraintNormalAng, const btVector3 &constraintNormalLin, const btVector3 &posAworld, const btVector3 &posBworld, btScalar posError, const btContactSolverInfo &infoGlobal, btScalar lowerLimit, btScalar upperLimit, bool angConstraint=false, btScalar relaxation=1.f, bool isFriction=false, btScalar desiredVelocity=0, btScalar cfmSlip=0, btScalar damping=1.0)
Definition: btMultiBodyConstraint.cpp:53
btMultiBodyConstraint::m_bodyA
btMultiBody * m_bodyA
Definition: btMultiBodyConstraint.h:59
btMultiBodyConstraint::m_linkB
int m_linkB
Definition: btMultiBodyConstraint.h:62
btMultiBodyConstraint::m_jacSizeBoth
int m_jacSizeBoth
Definition: btMultiBodyConstraint.h:68
btMultiBodyConstraint::getNumRows
int getNumRows() const
Definition: btMultiBodyConstraint.h:125
btMultiBodyConstraint::m_linkA
int m_linkA
Definition: btMultiBodyConstraint.h:61
btMultiBodyGearConstraint::~btMultiBodyGearConstraint
virtual ~btMultiBodyGearConstraint()
Definition: btMultiBodyGearConstraint.cpp:39
btMultiBodyGearConstraint::m_erp
btScalar m_erp
Definition: btMultiBodyGearConstraint.h:34
btMultiBodyGearConstraint::createConstraintRows
virtual void createConstraintRows(btMultiBodyConstraintArray &constraintRows, btMultiBodyJacobianData &data, const btContactSolverInfo &infoGlobal)
Definition: btMultiBodyGearConstraint.cpp:81
btMultiBodyGearConstraint::m_gearAuxLink
int m_gearAuxLink
Definition: btMultiBodyGearConstraint.h:33
btMultiBodyGearConstraint::m_relativePositionTarget
btScalar m_relativePositionTarget
Definition: btMultiBodyGearConstraint.h:35
btMultiBodyGearConstraint::btMultiBodyGearConstraint
btMultiBodyGearConstraint(btMultiBody *bodyA, int linkA, btMultiBody *bodyB, int linkB, const btVector3 &pivotInA, const btVector3 &pivotInB, const btMatrix3x3 &frameInA, const btMatrix3x3 &frameInB)
This file was written by Erwin Coumans.
Definition: btMultiBodyGearConstraint.cpp:23
btMultiBodyGearConstraint::finalizeMultiDof
virtual void finalizeMultiDof()
Definition: btMultiBodyGearConstraint.cpp:32
btMultiBodyGearConstraint::getIslandIdA
virtual int getIslandIdA() const
Definition: btMultiBodyGearConstraint.cpp:43
btMultiBodyGearConstraint::m_gearRatio
btScalar m_gearRatio
Definition: btMultiBodyGearConstraint.h:32
btMultiBodyGearConstraint::getIslandIdB
virtual int getIslandIdB() const
Definition: btMultiBodyGearConstraint.cpp:62
btMultiBodyLinkCollider
Definition: btMultiBodyLinkCollider.h:33
btMultiBody
Definition: btMultiBody.h:51
btMultiBody::getJointPosMultiDof
btScalar * getJointPosMultiDof(int i)
Definition: btMultiBody.cpp:388
btMultiBody::getLink
const btMultibodyLink & getLink(int index) const
Definition: btMultiBody.h:114
btMultiBody::getBaseCollider
const btMultiBodyLinkCollider * getBaseCollider() const
Definition: btMultiBody.h:128
btMultiBody::getJointVelMultiDof
btScalar * getJointVelMultiDof(int i)
Definition: btMultiBody.cpp:393
btTransform::getRotation
btQuaternion getRotation() const
Return a quaternion representing the rotation.
Definition: btTransform.h:119
btVector3
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:82
btVector3::setZero
void setZero()
Definition: btVector3.h:671
btContactSolverInfo
Definition: btContactSolverInfo.h:76
btMultiBodyJacobianData
Definition: btMultiBodyConstraint.h:44
btMultiBodySolverConstraint
1D constraint along a normal axis between bodyA and bodyB. It can be combined to solve contact and fr...
Definition: btMultiBodySolverConstraint.h:30
btMultiBodySolverConstraint::m_orgConstraint
btMultiBodyConstraint * m_orgConstraint
Definition: btMultiBodySolverConstraint.h:78
btMultiBodySolverConstraint::m_relpos1CrossNormal
btVector3 m_relpos1CrossNormal
Definition: btMultiBodySolverConstraint.h:42
btMultiBodySolverConstraint::m_contactNormal2
btVector3 m_contactNormal2
Definition: btMultiBodySolverConstraint.h:45
btMultiBodySolverConstraint::m_orgDofIndex
int m_orgDofIndex
Definition: btMultiBodySolverConstraint.h:79
btMultiBodySolverConstraint::m_contactNormal1
btVector3 m_contactNormal1
Definition: btMultiBodySolverConstraint.h:43
btMultiBodySolverConstraint::m_relpos2CrossNormal
btVector3 m_relpos2CrossNormal
Definition: btMultiBodySolverConstraint.h:44
btMultibodyLink::m_collider
class btMultiBodyLinkCollider * m_collider
Definition: btMultiBodyLink.h:132
btMultibodyLink::m_jointType
eFeatherstoneJointType m_jointType
Definition: btMultiBodyLink.h:137
btMultibodyLink::ePrismatic
@ ePrismatic
Definition: btMultiBodyLink.h:73
btMultibodyLink::eRevolute
@ eRevolute
Definition: btMultiBodyLink.h:72
btMultibodyLink::m_cachedWorldTransform
btTransform m_cachedWorldTransform
Definition: btMultiBodyLink.h:141
btMultibodyLink::m_dofOffset
int m_dofOffset
Definition: btMultiBodyLink.h:110
btMultibodyLink::m_axes
btSpatialMotionVector m_axes[6]
Definition: btMultiBodyLink.h:93
btSpatialMotionVector::m_bottomVec
btVector3 m_bottomVec
Definition: btSpatialAlgebra.h:96
btSpatialMotionVector::m_topVec
btVector3 m_topVec
Definition: btSpatialAlgebra.h:96