Bullet Collision Detection & Physics Library: btGeneric6DofSpringConstraint.cpp Source File

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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
16#include "btGeneric6DofSpringConstraint.h"
17#include "BulletDynamics/Dynamics/btRigidBody.h"
18#include "LinearMath/btTransformUtil.h"
19
20btGeneric6DofSpringConstraint::btGeneric6DofSpringConstraint(btRigidBody& rbA, btRigidBody& rbB, const btTransform& frameInA, const btTransform& frameInB, bool useLinearReferenceFrameA)
21 : btGeneric6DofConstraint(rbA, rbB, frameInA, frameInB, useLinearReferenceFrameA)
22{
23 init();
24}
25
26 btGeneric6DofSpringConstraint::btGeneric6DofSpringConstraint(btRigidBody& rbB, const btTransform& frameInB, bool useLinearReferenceFrameB)
27 : btGeneric6DofConstraint(rbB, frameInB, useLinearReferenceFrameB)
28{
29 init();
30}
31
32 void btGeneric6DofSpringConstraint::init()
33{
34 m_objectType = D6_SPRING_CONSTRAINT_TYPE;
35
36 for (int i = 0; i < 6; i++)
37 {
38 m_springEnabled[i] = false;
39 m_equilibriumPoint[i] = btScalar(0.f);
40 m_springStiffness[i] = btScalar(0.f);
41 m_springDamping[i] = btScalar(1.f);
42 }
43}
44
45 void btGeneric6DofSpringConstraint::enableSpring(int index, bool onOff)
46{
47 btAssert((index >= 0) && (index < 6));
48 m_springEnabled[index] = onOff;
49 if (index < 3)
50 {
51 m_linearLimits.m_enableMotor[index] = onOff;
52 }
53 else
54 {
55 m_angularLimits[index - 3].m_enableMotor = onOff;
56 }
57}
58
59 void btGeneric6DofSpringConstraint::setStiffness(int index, btScalar stiffness)
60{
61 btAssert((index >= 0) && (index < 6));
62 m_springStiffness[index] = stiffness;
63}
64
65 void btGeneric6DofSpringConstraint::setDamping(int index, btScalar damping)
66{
67 btAssert((index >= 0) && (index < 6));
68 m_springDamping[index] = damping;
69}
70
71 void btGeneric6DofSpringConstraint::setEquilibriumPoint()
72{
73 calculateTransforms();
74 int i;
75
76 for (i = 0; i < 3; i++)
77 {
78 m_equilibriumPoint[i] = m_calculatedLinearDiff[i];
79 }
80 for (i = 0; i < 3; i++)
81 {
82 m_equilibriumPoint[i + 3] = m_calculatedAxisAngleDiff[i];
83 }
84}
85
86 void btGeneric6DofSpringConstraint::setEquilibriumPoint(int index)
87{
88 btAssert((index >= 0) && (index < 6));
89 calculateTransforms();
90 if (index < 3)
91 {
92 m_equilibriumPoint[index] = m_calculatedLinearDiff[index];
93 }
94 else
95 {
96 m_equilibriumPoint[index] = m_calculatedAxisAngleDiff[index - 3];
97 }
98}
99
100 void btGeneric6DofSpringConstraint::setEquilibriumPoint(int index, btScalar val)
101{
102 btAssert((index >= 0) && (index < 6));
103 m_equilibriumPoint[index] = val;
104}
105
106 void btGeneric6DofSpringConstraint::internalUpdateSprings(btConstraintInfo2* info)
107{
108 // it is assumed that calculateTransforms() have been called before this call
109 int i;
110 //btVector3 relVel = m_rbB.getLinearVelocity() - m_rbA.getLinearVelocity();
111 for (i = 0; i < 3; i++)
112 {
113 if (m_springEnabled[i])
114 {
115 // get current position of constraint
116 btScalar currPos = m_calculatedLinearDiff[i];
117 // calculate difference
118 btScalar delta = currPos - m_equilibriumPoint[i];
119 // spring force is (delta * m_stiffness) according to Hooke's Law
120 btScalar force = delta * m_springStiffness[i];
121 btScalar velFactor = info->fps * m_springDamping[i] / btScalar(info->m_numIterations);
122 m_linearLimits.m_targetVelocity[i] = velFactor * force;
123 m_linearLimits.m_maxMotorForce[i] = btFabs(force);
124 }
125 }
126 for (i = 0; i < 3; i++)
127 {
128 if (m_springEnabled[i + 3])
129 {
130 // get current position of constraint
131 btScalar currPos = m_calculatedAxisAngleDiff[i];
132 // calculate difference
133 btScalar delta = currPos - m_equilibriumPoint[i + 3];
134 // spring force is (-delta * m_stiffness) according to Hooke's Law
135 btScalar force = -delta * m_springStiffness[i + 3];
136 btScalar velFactor = info->fps * m_springDamping[i + 3] / btScalar(info->m_numIterations);
137 m_angularLimits[i].m_targetVelocity = velFactor * force;
138 m_angularLimits[i].m_maxMotorForce = btFabs(force);
139 }
140 }
141}
142
143 void btGeneric6DofSpringConstraint::getInfo2(btConstraintInfo2* info)
144{
145 // this will be called by constraint solver at the constraint setup stage
146 // set current motor parameters
147 internalUpdateSprings(info);
148 // do the rest of job for constraint setup
149 btGeneric6DofConstraint::getInfo2(info);
150}
151
152 void btGeneric6DofSpringConstraint::setAxis(const btVector3& axis1, const btVector3& axis2)
153{
154 btVector3 zAxis = axis1.normalized();
155 btVector3 yAxis = axis2.normalized();
156 btVector3 xAxis = yAxis.cross(zAxis); // we want right coordinate system
157
158 btTransform frameInW;
159 frameInW.setIdentity();
160 frameInW.getBasis().setValue(xAxis[0], yAxis[0], zAxis[0],
161 xAxis[1], yAxis[1], zAxis[1],
162 xAxis[2], yAxis[2], zAxis[2]);
163
164 // now get constraint frame in local coordinate systems
165 m_frameInA = m_rbA.getCenterOfMassTransform().inverse() * frameInW;
166 m_frameInB = m_rbB.getCenterOfMassTransform().inverse() * frameInW;
167
168 calculateTransforms();
169}
btGeneric6DofSpringConstraint.h
btRigidBody.h
btScalar
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:314
btFabs
btScalar btFabs(btScalar x)
Definition: btScalar.h:497
btAssert
#define btAssert(x)
Definition: btScalar.h:153
btTransformUtil.h
D6_SPRING_CONSTRAINT_TYPE
@ D6_SPRING_CONSTRAINT_TYPE
Definition: btTypedConstraint.h:42
btGeneric6DofConstraint
btGeneric6DofConstraint between two rigidbodies each with a pivotpoint that descibes the axis locatio...
Definition: btGeneric6DofConstraint.h:268
btGeneric6DofConstraint::m_frameInA
btTransform m_frameInA
relative_frames
Definition: btGeneric6DofConstraint.h:272
btGeneric6DofConstraint::getInfo2
virtual void getInfo2(btConstraintInfo2 *info)
internal method used by the constraint solver, don't use them directly
Definition: btGeneric6DofConstraint.cpp:508
btGeneric6DofConstraint::m_calculatedLinearDiff
btVector3 m_calculatedLinearDiff
Definition: btGeneric6DofConstraint.h:300
btGeneric6DofConstraint::m_frameInB
btTransform m_frameInB
the constraint space w.r.t body B
Definition: btGeneric6DofConstraint.h:273
btGeneric6DofConstraint::calculateTransforms
void calculateTransforms()
Definition: btGeneric6DofConstraint.cpp:336
btGeneric6DofConstraint::m_linearLimits
btTranslationalLimitMotor m_linearLimits
Linear_Limit_parameters.
Definition: btGeneric6DofConstraint.h:284
btGeneric6DofConstraint::m_angularLimits
btRotationalLimitMotor m_angularLimits[3]
hinge_parameters
Definition: btGeneric6DofConstraint.h:289
btGeneric6DofConstraint::m_calculatedAxisAngleDiff
btVector3 m_calculatedAxisAngleDiff
Definition: btGeneric6DofConstraint.h:298
btGeneric6DofSpringConstraint::setAxis
virtual void setAxis(const btVector3 &axis1, const btVector3 &axis2)
Definition: btGeneric6DofSpringConstraint.cpp:152
btGeneric6DofSpringConstraint::init
void init()
Definition: btGeneric6DofSpringConstraint.cpp:32
btGeneric6DofSpringConstraint::getInfo2
virtual void getInfo2(btConstraintInfo2 *info)
internal method used by the constraint solver, don't use them directly
Definition: btGeneric6DofSpringConstraint.cpp:143
btGeneric6DofSpringConstraint::m_springDamping
btScalar m_springDamping[6]
Definition: btGeneric6DofSpringConstraint.h:48
btGeneric6DofSpringConstraint::internalUpdateSprings
void internalUpdateSprings(btConstraintInfo2 *info)
Definition: btGeneric6DofSpringConstraint.cpp:106
btGeneric6DofSpringConstraint::setDamping
void setDamping(int index, btScalar damping)
Definition: btGeneric6DofSpringConstraint.cpp:65
btGeneric6DofSpringConstraint::enableSpring
void enableSpring(int index, bool onOff)
Definition: btGeneric6DofSpringConstraint.cpp:45
btGeneric6DofSpringConstraint::setStiffness
void setStiffness(int index, btScalar stiffness)
Definition: btGeneric6DofSpringConstraint.cpp:59
btGeneric6DofSpringConstraint::m_equilibriumPoint
btScalar m_equilibriumPoint[6]
Definition: btGeneric6DofSpringConstraint.h:46
btGeneric6DofSpringConstraint::m_springEnabled
bool m_springEnabled[6]
Definition: btGeneric6DofSpringConstraint.h:45
btGeneric6DofSpringConstraint::btGeneric6DofSpringConstraint
btGeneric6DofSpringConstraint(btRigidBody &rbA, btRigidBody &rbB, const btTransform &frameInA, const btTransform &frameInB, bool useLinearReferenceFrameA)
Definition: btGeneric6DofSpringConstraint.cpp:20
btGeneric6DofSpringConstraint::setEquilibriumPoint
void setEquilibriumPoint()
Definition: btGeneric6DofSpringConstraint.cpp:71
btGeneric6DofSpringConstraint::m_springStiffness
btScalar m_springStiffness[6]
Definition: btGeneric6DofSpringConstraint.h:47
btMatrix3x3::setValue
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:204
btRigidBody
The btRigidBody is the main class for rigid body objects.
Definition: btRigidBody.h:60
btRigidBody::getCenterOfMassTransform
const btTransform & getCenterOfMassTransform() const
Definition: btRigidBody.h:429
btRotationalLimitMotor::m_targetVelocity
btScalar m_targetVelocity
target motor velocity
Definition: btGeneric6DofConstraint.h:51
btRotationalLimitMotor::m_maxMotorForce
btScalar m_maxMotorForce
max force on motor
Definition: btGeneric6DofConstraint.h:52
btRotationalLimitMotor::m_enableMotor
bool m_enableMotor
Definition: btGeneric6DofConstraint.h:60
btTransform
The btTransform class supports rigid transforms with only translation and rotation and no scaling/she...
Definition: btTransform.h:30
btTransform::inverse
btTransform inverse() const
Return the inverse of this transform.
Definition: btTransform.h:183
btTransform::getBasis
btMatrix3x3 & getBasis()
Return the basis matrix for the rotation.
Definition: btTransform.h:109
btTransform::setIdentity
void setIdentity()
Set this transformation to the identity.
Definition: btTransform.h:167
btTranslationalLimitMotor::m_maxMotorForce
btVector3 m_maxMotorForce
max force on motor
Definition: btGeneric6DofConstraint.h:148
btTranslationalLimitMotor::m_targetVelocity
btVector3 m_targetVelocity
target motor velocity
Definition: btGeneric6DofConstraint.h:147
btTranslationalLimitMotor::m_enableMotor
bool m_enableMotor[3]
Definition: btGeneric6DofConstraint.h:146
btTypedConstraint::m_rbA
btRigidBody & m_rbA
Definition: btTypedConstraint.h:97
btTypedConstraint::m_rbB
btRigidBody & m_rbB
Definition: btTypedConstraint.h:98
btVector3
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:82
btVector3::cross
btVector3 cross(const btVector3 &v) const
Return the cross product between this and another vector.
Definition: btVector3.h:380
btVector3::normalized
btVector3 normalized() const
Return a normalized version of this vector.
Definition: btVector3.h:949
btTypedConstraint::btConstraintInfo2
Definition: btTypedConstraint.h:121
btTypedConstraint::btConstraintInfo2::fps
btScalar fps
Definition: btTypedConstraint.h:124
btTypedConstraint::btConstraintInfo2::m_numIterations
int m_numIterations
Definition: btTypedConstraint.h:144
btTypedObject::m_objectType
int m_objectType
Definition: btScalar.h:805