Bullet Collision Detection & Physics Library
btMultiBodyGearConstraint.cpp
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1 /*
2 Bullet Continuous Collision Detection and Physics Library
3 Copyright (c) 2013 Erwin Coumans http://bulletphysics.org
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 
17 
19 #include "btMultiBody.h"
22 
23 btMultiBodyGearConstraint::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),
25  m_gearRatio(1),
26  m_gearAuxLink(-1),
27  m_erp(0),
28  m_relativePositionTarget(0)
29 {
30 }
31 
33 {
35 
37 }
38 
40 {
41 }
42 
44 {
45  if (m_bodyA)
46  {
47  if (m_linkA < 0)
48  {
50  if (col)
51  return col->getIslandTag();
52  }
53  else
54  {
57  }
58  }
59  return -1;
60 }
61 
63 {
64  if (m_bodyB)
65  {
66  if (m_linkB < 0)
67  {
69  if (col)
70  return col->getIslandTag();
71  }
72  else
73  {
76  }
77  }
78  return -1;
79 }
80 
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 
89  {
91  }
92 
93  //don't crash
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
154  {
156  {
157  constraintRow.m_contactNormal1.setZero();
158  constraintRow.m_contactNormal2.setZero();
160  constraintRow.m_relpos1CrossNormal = revoluteAxisInWorld;
161  constraintRow.m_relpos2CrossNormal = -revoluteAxisInWorld;
162 
163  break;
164  }
166  {
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 }
btMultiBodySolverConstraint::m_relpos1CrossNormal
btVector3 m_relpos1CrossNormal
Definition: btMultiBodySolverConstraint.h:42
btTransform::getRotation
btQuaternion getRotation() const
Return a quaternion representing the rotation.
Definition: btTransform.h:118
btMultiBody::getJointPosMultiDof
btScalar * getJointPosMultiDof(int i)
Definition: btMultiBody.cpp:378
btMultiBodySolverConstraint::m_orgConstraint
btMultiBodyConstraint * m_orgConstraint
Definition: btMultiBodySolverConstraint.h:78
btContactSolverInfo
Definition: btContactSolverInfo.h:69
btMultiBodyGearConstraint::createConstraintRows
virtual void createConstraintRows(btMultiBodyConstraintArray &constraintRows, btMultiBodyJacobianData &data, const btContactSolverInfo &infoGlobal)
Definition: btMultiBodyGearConstraint.cpp:81
btScalar
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:294
btMultiBodyGearConstraint::finalizeMultiDof
virtual void finalizeMultiDof()
Definition: btMultiBodyGearConstraint.cpp:32
btMultiBodyGearConstraint::getIslandIdB
virtual int getIslandIdB() const
Definition: btMultiBodyGearConstraint.cpp:62
btMultiBodyConstraint
Definition: btMultiBodyConstraint.h:40
btMultiBody::getJointVelMultiDof
btScalar * getJointVelMultiDof(int i)
Definition: btMultiBody.cpp:383
btMultiBodyConstraint::m_linkA
int m_linkA
Definition: btMultiBodyConstraint.h:46
btMultiBodyGearConstraint::~btMultiBodyGearConstraint
virtual ~btMultiBodyGearConstraint()
Definition: btMultiBodyGearConstraint.cpp:39
btMultiBodyConstraint::getNumRows
int getNumRows() const
Definition: btMultiBodyConstraint.h:104
btVector3::setZero
void setZero()
Definition: btVector3.h:671
btMultiBodyJacobianData
Definition: btMultiBodyConstraint.h:28
btMultiBodyGearConstraint::m_relativePositionTarget
btScalar m_relativePositionTarget
Definition: btMultiBodyGearConstraint.h:35
btAssert
#define btAssert(x)
Definition: btScalar.h:133
btMultiBodySolverConstraint
1D constraint along a normal axis between bodyA and bodyB. It can be combined to solve contact and fr...
Definition: btMultiBodySolverConstraint.h:28
btMultiBodyGearConstraint.h
btMultiBodyGearConstraint::getIslandIdA
virtual int getIslandIdA() const
Definition: btMultiBodyGearConstraint.cpp:43
btMultiBodyLinkCollider.h
btMultiBodyConstraint::m_linkB
int m_linkB
Definition: btMultiBodyConstraint.h:47
btMultiBodyConstraint::m_maxAppliedImpulse
btScalar m_maxAppliedImpulse
Definition: btMultiBodyConstraint.h:56
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)
Definition: btMultiBodyConstraint.cpp:52
btMatrix3x3
The btMatrix3x3 class implements a 3x3 rotation matrix, to perform linear algebra in combination with...
Definition: btMatrix3x3.h:46
btMultiBodyLinkCollider
Definition: btMultiBodyLinkCollider.h:32
btMultiBody::getLink
const btMultibodyLink & getLink(int index) const
Definition: btMultiBody.h:114
btVector3
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:80
btSpatialMotionVector::m_bottomVec
btVector3 m_bottomVec
Definition: btSpatialAlgebra.h:96
btMultiBody
Definition: btMultiBody.h:49
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
btCollisionObject::getIslandTag
int getIslandTag() const
Definition: btCollisionObject.h:434
btMultiBodyConstraint::m_numDofsFinalized
int m_numDofsFinalized
Definition: btMultiBodyConstraint.h:55
btAlignedObjectArray< btMultiBodySolverConstraint >
btMultiBodyConstraint::allocateJacobiansMultiDof
void allocateJacobiansMultiDof()
Definition: btMultiBodyConstraint.cpp:34
btMultiBodyConstraint::jacobianA
btScalar * jacobianA(int row)
Definition: btMultiBodyConstraint.h:160
btMultiBody.h
btMultiBodyConstraint::m_bodyA
btMultiBody * m_bodyA
Definition: btMultiBodyConstraint.h:44
btMultiBodySolverConstraint::m_orgDofIndex
int m_orgDofIndex
Definition: btMultiBodySolverConstraint.h:79
btMultiBodySolverConstraint::m_contactNormal1
btVector3 m_contactNormal1
Definition: btMultiBodySolverConstraint.h:43
btCollisionObject.h
btMultiBodyConstraint::m_jacSizeBoth
int m_jacSizeBoth
Definition: btMultiBodyConstraint.h:51
btMultiBodyConstraint::jacobianB
btScalar * jacobianB(int row)
Definition: btMultiBodyConstraint.h:168
btSpatialMotionVector::m_topVec
btVector3 m_topVec
Definition: btSpatialAlgebra.h:96
btMultiBodySolverConstraint::m_relpos2CrossNormal
btVector3 m_relpos2CrossNormal
Definition: btMultiBodySolverConstraint.h:44
btMultiBodyGearConstraint::m_erp
btScalar m_erp
Definition: btMultiBodyGearConstraint.h:34
btAlignedObjectArray::expandNonInitializing
T & expandNonInitializing()
Definition: btAlignedObjectArray.h:237
btMultiBodySolverConstraint::m_contactNormal2
btVector3 m_contactNormal2
Definition: btMultiBodySolverConstraint.h:45
btMultiBodyGearConstraint::m_gearAuxLink
int m_gearAuxLink
Definition: btMultiBodyGearConstraint.h:33
btMultiBody::getBaseCollider
const btMultiBodyLinkCollider * getBaseCollider() const
Definition: btMultiBody.h:128
btMultiBodyConstraint::m_bodyB
btMultiBody * m_bodyB
Definition: btMultiBodyConstraint.h:45
btMultiBodyGearConstraint::m_gearRatio
btScalar m_gearRatio
Definition: btMultiBodyGearConstraint.h:32
quatRotate
btVector3 quatRotate(const btQuaternion &rotation, const btVector3 &v)
Definition: btQuaternion.h:926