1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
|
/*
Bullet Continuous Collision Detection and Physics Library
Copyright (c) 2013 Erwin Coumans http://bulletphysics.org
This software is provided 'as-is', without any express or implied warranty.
In no event will the authors be held liable for any damages arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it freely,
subject to the following restrictions:
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.
2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
*/
///This file was written by Erwin Coumans
#include "btMultiBodyJointLimitConstraint.h"
#include "btMultiBody.h"
#include "btMultiBodyLinkCollider.h"
#include "BulletCollision/CollisionDispatch/btCollisionObject.h"
btMultiBodyJointLimitConstraint::btMultiBodyJointLimitConstraint(btMultiBody* body, int link, btScalar lower, btScalar upper)
//:btMultiBodyConstraint(body,0,link,-1,2,true),
: btMultiBodyConstraint(body, body, link, body->getLink(link).m_parent, 2, true, MULTIBODY_CONSTRAINT_LIMIT),
m_lowerBound(lower),
m_upperBound(upper)
{
}
void btMultiBodyJointLimitConstraint::finalizeMultiDof()
{
// the data.m_jacobians never change, so may as well
// initialize them here
allocateJacobiansMultiDof();
unsigned int offset = 6 + m_bodyA->getLink(m_linkA).m_dofOffset;
// row 0: the lower bound
jacobianA(0)[offset] = 1;
// row 1: the upper bound
//jacobianA(1)[offset] = -1;
jacobianB(1)[offset] = -1;
m_numDofsFinalized = m_jacSizeBoth;
}
btMultiBodyJointLimitConstraint::~btMultiBodyJointLimitConstraint()
{
}
int btMultiBodyJointLimitConstraint::getIslandIdA() const
{
if (m_bodyA)
{
if (m_linkA < 0)
{
btMultiBodyLinkCollider* col = m_bodyA->getBaseCollider();
if (col)
return col->getIslandTag();
}
else
{
if (m_bodyA->getLink(m_linkA).m_collider)
return m_bodyA->getLink(m_linkA).m_collider->getIslandTag();
}
}
return -1;
}
int btMultiBodyJointLimitConstraint::getIslandIdB() const
{
if (m_bodyB)
{
if (m_linkB < 0)
{
btMultiBodyLinkCollider* col = m_bodyB->getBaseCollider();
if (col)
return col->getIslandTag();
}
else
{
if (m_bodyB->getLink(m_linkB).m_collider)
return m_bodyB->getLink(m_linkB).m_collider->getIslandTag();
}
}
return -1;
}
void btMultiBodyJointLimitConstraint::createConstraintRows(btMultiBodyConstraintArray& constraintRows,
btMultiBodyJacobianData& data,
const btContactSolverInfo& infoGlobal)
{
// only positions need to be updated -- data.m_jacobians and force
// directions were set in the ctor and never change.
if (m_numDofsFinalized != m_jacSizeBoth)
{
finalizeMultiDof();
}
// row 0: the lower bound
setPosition(0, m_bodyA->getJointPos(m_linkA) - m_lowerBound); //multidof: this is joint-type dependent
// row 1: the upper bound
setPosition(1, m_upperBound - m_bodyA->getJointPos(m_linkA));
for (int row = 0; row < getNumRows(); row++)
{
btScalar penetration = getPosition(row);
//todo: consider adding some safety threshold here
if (penetration > 0)
{
continue;
}
btScalar direction = row ? -1 : 1;
btMultiBodySolverConstraint& constraintRow = constraintRows.expandNonInitializing();
constraintRow.m_orgConstraint = this;
constraintRow.m_orgDofIndex = row;
constraintRow.m_multiBodyA = m_bodyA;
constraintRow.m_multiBodyB = m_bodyB;
const btScalar posError = 0; //why assume it's zero?
const btVector3 dummy(0, 0, 0);
btScalar rel_vel = fillMultiBodyConstraint(constraintRow, data, jacobianA(row), jacobianB(row), dummy, dummy, dummy, dummy, posError, infoGlobal, 0, m_maxAppliedImpulse);
{
//expect either prismatic or revolute joint type for now
btAssert((m_bodyA->getLink(m_linkA).m_jointType == btMultibodyLink::eRevolute) || (m_bodyA->getLink(m_linkA).m_jointType == btMultibodyLink::ePrismatic));
switch (m_bodyA->getLink(m_linkA).m_jointType)
{
case btMultibodyLink::eRevolute:
{
constraintRow.m_contactNormal1.setZero();
constraintRow.m_contactNormal2.setZero();
btVector3 revoluteAxisInWorld = direction * quatRotate(m_bodyA->getLink(m_linkA).m_cachedWorldTransform.getRotation(), m_bodyA->getLink(m_linkA).m_axes[0].m_topVec);
constraintRow.m_relpos1CrossNormal = revoluteAxisInWorld;
constraintRow.m_relpos2CrossNormal = -revoluteAxisInWorld;
break;
}
case btMultibodyLink::ePrismatic:
{
btVector3 prismaticAxisInWorld = direction * quatRotate(m_bodyA->getLink(m_linkA).m_cachedWorldTransform.getRotation(), m_bodyA->getLink(m_linkA).m_axes[0].m_bottomVec);
constraintRow.m_contactNormal1 = prismaticAxisInWorld;
constraintRow.m_contactNormal2 = -prismaticAxisInWorld;
constraintRow.m_relpos1CrossNormal.setZero();
constraintRow.m_relpos2CrossNormal.setZero();
break;
}
default:
{
btAssert(0);
}
};
}
{
btScalar positionalError = 0.f;
btScalar velocityError = -rel_vel; // * damping;
btScalar erp = infoGlobal.m_erp2;
if (!infoGlobal.m_splitImpulse || (penetration > infoGlobal.m_splitImpulsePenetrationThreshold))
{
erp = infoGlobal.m_erp;
}
if (penetration > 0)
{
positionalError = 0;
velocityError = -penetration / infoGlobal.m_timeStep;
}
else
{
positionalError = -penetration * erp / infoGlobal.m_timeStep;
}
btScalar penetrationImpulse = positionalError * constraintRow.m_jacDiagABInv;
btScalar velocityImpulse = velocityError * constraintRow.m_jacDiagABInv;
if (!infoGlobal.m_splitImpulse || (penetration > infoGlobal.m_splitImpulsePenetrationThreshold))
{
//combine position and velocity into rhs
constraintRow.m_rhs = penetrationImpulse + velocityImpulse;
constraintRow.m_rhsPenetration = 0.f;
}
else
{
//split position and velocity into rhs and m_rhsPenetration
constraintRow.m_rhs = velocityImpulse;
constraintRow.m_rhsPenetration = penetrationImpulse;
}
}
}
}
|
