Bullet Collision Detection & Physics Library
btMultiBodyJointLimitConstraint.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 
24 
26  //:btMultiBodyConstraint(body,0,link,-1,2,true),
27  :btMultiBodyConstraint(body,body,link,body->getLink(link).m_parent,2,true),
28  m_lowerBound(lower),
29  m_upperBound(upper)
30 {
31 
32 }
33 
35 {
36  // the data.m_jacobians never change, so may as well
37  // initialize them here
38 
40 
41  unsigned int offset = 6 + m_bodyA->getLink(m_linkA).m_dofOffset;
42 
43  // row 0: the lower bound
44  jacobianA(0)[offset] = 1;
45  // row 1: the upper bound
46  //jacobianA(1)[offset] = -1;
47  jacobianB(1)[offset] = -1;
48 
50 }
51 
53 {
54 }
55 
57 {
58  if(m_bodyA)
59  {
61  if (col)
62  return col->getIslandTag();
63  for (int i=0;i<m_bodyA->getNumLinks();i++)
64  {
65  if (m_bodyA->getLink(i).m_collider)
66  return m_bodyA->getLink(i).m_collider->getIslandTag();
67  }
68  }
69  return -1;
70 }
71 
73 {
74  if(m_bodyB)
75  {
77  if (col)
78  return col->getIslandTag();
79 
80  for (int i=0;i<m_bodyB->getNumLinks();i++)
81  {
82  col = m_bodyB->getLink(i).m_collider;
83  if (col)
84  return col->getIslandTag();
85  }
86  }
87  return -1;
88 }
89 
90 
93  const btContactSolverInfo& infoGlobal)
94 {
95 
96  // only positions need to be updated -- data.m_jacobians and force
97  // directions were set in the ctor and never change.
98 
100  {
102  }
103 
104 
105  // row 0: the lower bound
106  setPosition(0, m_bodyA->getJointPos(m_linkA) - m_lowerBound); //multidof: this is joint-type dependent
107 
108  // row 1: the upper bound
110 
111  for (int row=0;row<getNumRows();row++)
112  {
113 
114  btScalar direction = row? -1 : 1;
115 
116  btMultiBodySolverConstraint& constraintRow = constraintRows.expandNonInitializing();
117  constraintRow.m_orgConstraint = this;
118  constraintRow.m_orgDofIndex = row;
119 
120  constraintRow.m_multiBodyA = m_bodyA;
121  constraintRow.m_multiBodyB = m_bodyB;
122  const btScalar posError = 0; //why assume it's zero?
123  const btVector3 dummy(0, 0, 0);
124 
125  btScalar rel_vel = fillMultiBodyConstraint(constraintRow,data,jacobianA(row),jacobianB(row),dummy,dummy,dummy,dummy,posError,infoGlobal,0,m_maxAppliedImpulse);
126 
127  {
128  //expect either prismatic or revolute joint type for now
131  {
133  {
134  constraintRow.m_contactNormal1.setZero();
135  constraintRow.m_contactNormal2.setZero();
137  constraintRow.m_relpos1CrossNormal=revoluteAxisInWorld;
138  constraintRow.m_relpos2CrossNormal=-revoluteAxisInWorld;
139 
140  break;
141  }
143  {
145  constraintRow.m_contactNormal1=prismaticAxisInWorld;
146  constraintRow.m_contactNormal2=-prismaticAxisInWorld;
147  constraintRow.m_relpos1CrossNormal.setZero();
148  constraintRow.m_relpos2CrossNormal.setZero();
149 
150  break;
151  }
152  default:
153  {
154  btAssert(0);
155  }
156  };
157 
158  }
159 
160  {
161  btScalar penetration = getPosition(row);
162  btScalar positionalError = 0.f;
163  btScalar velocityError = - rel_vel;// * damping;
164  btScalar erp = infoGlobal.m_erp2;
165  if (!infoGlobal.m_splitImpulse || (penetration > infoGlobal.m_splitImpulsePenetrationThreshold))
166  {
167  erp = infoGlobal.m_erp;
168  }
169  if (penetration>0)
170  {
171  positionalError = 0;
172  velocityError = -penetration / infoGlobal.m_timeStep;
173  } else
174  {
175  positionalError = -penetration * erp/infoGlobal.m_timeStep;
176  }
177 
178  btScalar penetrationImpulse = positionalError*constraintRow.m_jacDiagABInv;
179  btScalar velocityImpulse = velocityError *constraintRow.m_jacDiagABInv;
180  if (!infoGlobal.m_splitImpulse || (penetration > infoGlobal.m_splitImpulsePenetrationThreshold))
181  {
182  //combine position and velocity into rhs
183  constraintRow.m_rhs = penetrationImpulse+velocityImpulse;
184  constraintRow.m_rhsPenetration = 0.f;
185 
186  } else
187  {
188  //split position and velocity into rhs and m_rhsPenetration
189  constraintRow.m_rhs = velocityImpulse;
190  constraintRow.m_rhsPenetration = penetrationImpulse;
191  }
192  }
193  }
194 
195 }
196 
197 
198 
199 
btScalar * jacobianB(int row)
virtual void createConstraintRows(btMultiBodyConstraintArray &constraintRows, btMultiBodyJacobianData &data, const btContactSolverInfo &infoGlobal)
int getNumLinks() const
Definition: btMultiBody.h:155
1D constraint along a normal axis between bodyA and bodyB. It can be combined to solve contact and fr...
const btMultiBodyLinkCollider * getBaseCollider() const
Definition: btMultiBody.h:134
btMultiBodyConstraint * m_orgConstraint
#define btAssert(x)
Definition: btScalar.h:114
btScalar * jacobianA(int row)
btQuaternion getRotation() const
Return a quaternion representing the rotation.
Definition: btTransform.h:122
btScalar getPosition(int row) const
btVector3 quatRotate(const btQuaternion &rotation, const btVector3 &v)
Definition: btQuaternion.h:887
void setZero()
Definition: btVector3.h:681
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:83
const btMultibodyLink & getLink(int index) const
Definition: btMultiBody.h:119
btMultiBodyJointLimitConstraint(btMultiBody *body, int link, btScalar lower, btScalar upper)
This file was written by Erwin Coumans.
int getIslandTag() const
void setPosition(int row, btScalar pos)
btScalar getJointPos(int i) const
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)
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:279