Bullet Collision Detection & Physics Library
btGeneric6DofSpringConstraint.cpp
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1/*
2Bullet Continuous Collision Detection and Physics Library, http://bulletphysics.org
3Copyright (C) 2006, 2007 Sony Computer Entertainment Inc.
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
19
20
21btGeneric6DofSpringConstraint::btGeneric6DofSpringConstraint(btRigidBody& rbA, btRigidBody& rbB, const btTransform& frameInA, const btTransform& frameInB ,bool useLinearReferenceFrameA)
22 : btGeneric6DofConstraint(rbA, rbB, frameInA, frameInB, useLinearReferenceFrameA)
23{
24 init();
25}
26
27
29 : btGeneric6DofConstraint(rbB, frameInB, useLinearReferenceFrameB)
30{
31 init();
32}
33
34
36{
38
39 for(int i = 0; i < 6; i++)
40 {
41 m_springEnabled[i] = false;
44 m_springDamping[i] = btScalar(1.f);
45 }
46}
47
48
50{
51 btAssert((index >= 0) && (index < 6));
52 m_springEnabled[index] = onOff;
53 if(index < 3)
54 {
55 m_linearLimits.m_enableMotor[index] = onOff;
56 }
57 else
58 {
59 m_angularLimits[index - 3].m_enableMotor = onOff;
60 }
61}
62
63
64
66{
67 btAssert((index >= 0) && (index < 6));
68 m_springStiffness[index] = stiffness;
69}
70
71
73{
74 btAssert((index >= 0) && (index < 6));
75 m_springDamping[index] = damping;
76}
77
78
80{
82 int i;
83
84 for( i = 0; i < 3; i++)
85 {
87 }
88 for(i = 0; i < 3; i++)
89 {
91 }
92}
93
94
95
97{
98 btAssert((index >= 0) && (index < 6));
100 if(index < 3)
101 {
103 }
104 else
105 {
107 }
108}
109
111{
112 btAssert((index >= 0) && (index < 6));
113 m_equilibriumPoint[index] = val;
114}
115
116
118{
119 // it is assumed that calculateTransforms() have been called before this call
120 int i;
121 //btVector3 relVel = m_rbB.getLinearVelocity() - m_rbA.getLinearVelocity();
122 for(i = 0; i < 3; i++)
123 {
124 if(m_springEnabled[i])
125 {
126 // get current position of constraint
127 btScalar currPos = m_calculatedLinearDiff[i];
128 // calculate difference
129 btScalar delta = currPos - m_equilibriumPoint[i];
130 // spring force is (delta * m_stiffness) according to Hooke's Law
131 btScalar force = delta * m_springStiffness[i];
132 btScalar velFactor = info->fps * m_springDamping[i] / btScalar(info->m_numIterations);
133 m_linearLimits.m_targetVelocity[i] = velFactor * force;
134 m_linearLimits.m_maxMotorForce[i] = btFabs(force) / info->fps;
135 }
136 }
137 for(i = 0; i < 3; i++)
138 {
139 if(m_springEnabled[i + 3])
140 {
141 // get current position of constraint
143 // calculate difference
144 btScalar delta = currPos - m_equilibriumPoint[i+3];
145 // spring force is (-delta * m_stiffness) according to Hooke's Law
146 btScalar force = -delta * m_springStiffness[i+3];
147 btScalar velFactor = info->fps * m_springDamping[i+3] / btScalar(info->m_numIterations);
148 m_angularLimits[i].m_targetVelocity = velFactor * force;
149 m_angularLimits[i].m_maxMotorForce = btFabs(force) / info->fps;
150 }
151 }
152}
153
154
156{
157 // this will be called by constraint solver at the constraint setup stage
158 // set current motor parameters
160 // do the rest of job for constraint setup
162}
163
164
166{
167 btVector3 zAxis = axis1.normalized();
168 btVector3 yAxis = axis2.normalized();
169 btVector3 xAxis = yAxis.cross(zAxis); // we want right coordinate system
170
171 btTransform frameInW;
172 frameInW.setIdentity();
173 frameInW.getBasis().setValue( xAxis[0], yAxis[0], zAxis[0],
174 xAxis[1], yAxis[1], zAxis[1],
175 xAxis[2], yAxis[2], zAxis[2]);
176
177 // now get constraint frame in local coordinate systems
180
182}
183
184
185
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:292
btScalar btFabs(btScalar x)
Definition: btScalar.h:475
#define btAssert(x)
Definition: btScalar.h:131
@ D6_SPRING_CONSTRAINT_TYPE
btGeneric6DofConstraint between two rigidbodies each with a pivotpoint that descibes the axis locatio...
btTransform m_frameInA
relative_frames
virtual void getInfo2(btConstraintInfo2 *info)
internal method used by the constraint solver, don't use them directly
btTransform m_frameInB
the constraint space w.r.t body B
btTranslationalLimitMotor m_linearLimits
Linear_Limit_parameters.
btRotationalLimitMotor m_angularLimits[3]
hinge_parameters
virtual void setAxis(const btVector3 &axis1, const btVector3 &axis2)
virtual void getInfo2(btConstraintInfo2 *info)
internal method used by the constraint solver, don't use them directly
void internalUpdateSprings(btConstraintInfo2 *info)
void setDamping(int index, btScalar damping)
void setStiffness(int index, btScalar stiffness)
btGeneric6DofSpringConstraint(btRigidBody &rbA, btRigidBody &rbB, const btTransform &frameInA, const btTransform &frameInB, bool useLinearReferenceFrameA)
void setValue(const btScalar &xx, const btScalar &xy, const btScalar &xz, const btScalar &yx, const btScalar &yy, const btScalar &yz, const btScalar &zx, const btScalar &zy, const btScalar &zz)
Set the values of the matrix explicitly (row major)
Definition: btMatrix3x3.h:198
The btRigidBody is the main class for rigid body objects.
Definition: btRigidBody.h:63
const btTransform & getCenterOfMassTransform() const
Definition: btRigidBody.h:359
btScalar m_targetVelocity
target motor velocity
btScalar m_maxMotorForce
max force on motor
The btTransform class supports rigid transforms with only translation and rotation and no scaling/she...
Definition: btTransform.h:34
btTransform inverse() const
Return the inverse of this transform.
Definition: btTransform.h:188
btMatrix3x3 & getBasis()
Return the basis matrix for the rotation.
Definition: btTransform.h:112
void setIdentity()
Set this transformation to the identity.
Definition: btTransform.h:172
btVector3 m_maxMotorForce
max force on motor
btVector3 m_targetVelocity
target motor velocity
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:84
btVector3 cross(const btVector3 &v) const
Return the cross product between this and another vector.
Definition: btVector3.h:389
btVector3 normalized() const
Return a normalized version of this vector.
Definition: btVector3.h:964
int m_objectType
Definition: btScalar.h:783