Bullet Collision Detection & Physics Library
btGeneric6DofSpringConstraint.cpp
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2 Bullet Continuous Collision Detection and Physics Library, http://bulletphysics.org
3 Copyright (C) 2006, 2007 Sony Computer Entertainment Inc.
4 
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15 
19 
20 btGeneric6DofSpringConstraint::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 
33 {
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 
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 
60 {
61  btAssert((index >= 0) && (index < 6));
62  m_springStiffness[index] = stiffness;
63 }
64 
66 {
67  btAssert((index >= 0) && (index < 6));
68  m_springDamping[index] = damping;
69 }
70 
72 {
74  int i;
75 
76  for (i = 0; i < 3; i++)
77  {
79  }
80  for (i = 0; i < 3; i++)
81  {
83  }
84 }
85 
87 {
88  btAssert((index >= 0) && (index < 6));
90  if (index < 3)
91  {
93  }
94  else
95  {
97  }
98 }
99 
101 {
102  btAssert((index >= 0) && (index < 6));
103  m_equilibriumPoint[index] = val;
104 }
105 
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;
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;
139  }
140  }
141 }
142 
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
150 }
151 
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
167 
169 }
btRigidBody
The btRigidBody is the main class for rigid body objects.
Definition: btRigidBody.h:59
btTransform::inverse
btTransform inverse() const
Return the inverse of this transform.
Definition: btTransform.h:182
btScalar
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:294
btTypedObject::m_objectType
int m_objectType
Definition: btScalar.h:785
btVector3::cross
btVector3 cross(const btVector3 &v) const
Return the cross product between this and another vector.
Definition: btVector3.h:380
btGeneric6DofSpringConstraint::m_equilibriumPoint
btScalar m_equilibriumPoint[6]
Definition: btGeneric6DofSpringConstraint.h:46
btGeneric6DofSpringConstraint::getInfo2
virtual void getInfo2(btConstraintInfo2 *info)
internal method used by the constraint solver, don't use them directly
Definition: btGeneric6DofSpringConstraint.cpp:143
btRigidBody.h
btGeneric6DofSpringConstraint::internalUpdateSprings
void internalUpdateSprings(btConstraintInfo2 *info)
Definition: btGeneric6DofSpringConstraint.cpp:106
btGeneric6DofSpringConstraint::m_springDamping
btScalar m_springDamping[6]
Definition: btGeneric6DofSpringConstraint.h:48
btGeneric6DofConstraint
btGeneric6DofConstraint between two rigidbodies each with a pivotpoint that descibes the axis locatio...
Definition: btGeneric6DofConstraint.h:266
btTransformUtil.h
btRigidBody::getCenterOfMassTransform
const btTransform & getCenterOfMassTransform() const
Definition: btRigidBody.h:349
btGeneric6DofSpringConstraint::setDamping
void setDamping(int index, btScalar damping)
Definition: btGeneric6DofSpringConstraint.cpp:65
btTransform::setIdentity
void setIdentity()
Set this transformation to the identity.
Definition: btTransform.h:166
btGeneric6DofSpringConstraint::setStiffness
void setStiffness(int index, btScalar stiffness)
Definition: btGeneric6DofSpringConstraint.cpp:59
btAssert
#define btAssert(x)
Definition: btScalar.h:133
btFabs
btScalar btFabs(btScalar x)
Definition: btScalar.h:477
btGeneric6DofConstraint::calculateTransforms
void calculateTransforms()
Definition: btGeneric6DofConstraint.cpp:336
btRotationalLimitMotor::m_maxMotorForce
btScalar m_maxMotorForce
max force on motor
Definition: btGeneric6DofConstraint.h:52
btGeneric6DofConstraint::m_linearLimits
btTranslationalLimitMotor m_linearLimits
Linear_Limit_parameters.
Definition: btGeneric6DofConstraint.h:284
btGeneric6DofConstraint::m_calculatedLinearDiff
btVector3 m_calculatedLinearDiff
Definition: btGeneric6DofConstraint.h:300
btTransform::getBasis
btMatrix3x3 & getBasis()
Return the basis matrix for the rotation.
Definition: btTransform.h:108
btGeneric6DofConstraint::getInfo2
virtual void getInfo2(btConstraintInfo2 *info)
internal method used by the constraint solver, don't use them directly
Definition: btGeneric6DofConstraint.cpp:508
btGeneric6DofSpringConstraint::m_springStiffness
btScalar m_springStiffness[6]
Definition: btGeneric6DofSpringConstraint.h:47
btGeneric6DofConstraint::m_angularLimits
btRotationalLimitMotor m_angularLimits[3]
hinge_parameters
Definition: btGeneric6DofConstraint.h:289
btGeneric6DofSpringConstraint::enableSpring
void enableSpring(int index, bool onOff)
Definition: btGeneric6DofSpringConstraint.cpp:45
btTransform
The btTransform class supports rigid transforms with only translation and rotation and no scaling/she...
Definition: btTransform.h:28
btGeneric6DofSpringConstraint::setEquilibriumPoint
void setEquilibriumPoint()
Definition: btGeneric6DofSpringConstraint.cpp:71
btTranslationalLimitMotor::m_targetVelocity
btVector3 m_targetVelocity
target motor velocity
Definition: btGeneric6DofConstraint.h:147
btGeneric6DofConstraint::m_calculatedAxisAngleDiff
btVector3 m_calculatedAxisAngleDiff
Definition: btGeneric6DofConstraint.h:298
btVector3
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:80
btTranslationalLimitMotor::m_maxMotorForce
btVector3 m_maxMotorForce
max force on motor
Definition: btGeneric6DofConstraint.h:148
D6_SPRING_CONSTRAINT_TYPE
Definition: btTypedConstraint.h:42
btGeneric6DofConstraint::m_frameInA
btTransform m_frameInA
relative_frames
Definition: btGeneric6DofConstraint.h:272
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:195
btGeneric6DofSpringConstraint::init
void init()
Definition: btGeneric6DofSpringConstraint.cpp:32
btGeneric6DofConstraint::m_frameInB
btTransform m_frameInB
the constraint space w.r.t body B
Definition: btGeneric6DofConstraint.h:273
btTypedConstraint::btConstraintInfo2::m_numIterations
int m_numIterations
Definition: btTypedConstraint.h:144
btTypedConstraint::btConstraintInfo2
Definition: btTypedConstraint.h:120
btTypedConstraint::m_rbB
btRigidBody & m_rbB
Definition: btTypedConstraint.h:98
btTypedConstraint::btConstraintInfo2::fps
btScalar fps
Definition: btTypedConstraint.h:124
btGeneric6DofSpringConstraint::setAxis
virtual void setAxis(const btVector3 &axis1, const btVector3 &axis2)
Definition: btGeneric6DofSpringConstraint.cpp:152
btGeneric6DofSpringConstraint.h
btRotationalLimitMotor::m_enableMotor
bool m_enableMotor
Definition: btGeneric6DofConstraint.h:60
btGeneric6DofSpringConstraint::m_springEnabled
bool m_springEnabled[6]
Definition: btGeneric6DofSpringConstraint.h:45
btTranslationalLimitMotor::m_enableMotor
bool m_enableMotor[3]
Definition: btGeneric6DofConstraint.h:146
btVector3::normalized
btVector3 normalized() const
Return a normalized version of this vector.
Definition: btVector3.h:949
btTypedConstraint::m_rbA
btRigidBody & m_rbA
Definition: btTypedConstraint.h:97
btGeneric6DofSpringConstraint::btGeneric6DofSpringConstraint
btGeneric6DofSpringConstraint(btRigidBody &rbA, btRigidBody &rbB, const btTransform &frameInA, const btTransform &frameInB, bool useLinearReferenceFrameA)
Definition: btGeneric6DofSpringConstraint.cpp:20
btRotationalLimitMotor::m_targetVelocity
btScalar m_targetVelocity
target motor velocity
Definition: btGeneric6DofConstraint.h:51