Bullet Collision Detection & Physics Library
btGeneric6DofSpringConstraint.cpp
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1 /*
2 Bullet Continuous Collision Detection and Physics Library, http://bulletphysics.org
3 Copyright (C) 2006, 2007 Sony Computer Entertainment Inc.
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.
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8 including commercial applications, and to alter it and redistribute it freely,
9 subject to the following restrictions:
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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 
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 }
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:314
btScalar btFabs(btScalar x)
Definition: btScalar.h:497
#define btAssert(x)
Definition: btScalar.h:153
@ 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:204
The btRigidBody is the main class for rigid body objects.
Definition: btRigidBody.h:60
const btTransform & getCenterOfMassTransform() const
Definition: btRigidBody.h:429
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:30
btTransform inverse() const
Return the inverse of this transform.
Definition: btTransform.h:182
btMatrix3x3 & getBasis()
Return the basis matrix for the rotation.
Definition: btTransform.h:108
void setIdentity()
Set this transformation to the identity.
Definition: btTransform.h:166
btVector3 m_maxMotorForce
max force on motor
btVector3 m_targetVelocity
target motor velocity
btRigidBody & m_rbA
btRigidBody & m_rbB
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:82
btVector3 cross(const btVector3 &v) const
Return the cross product between this and another vector.
Definition: btVector3.h:380
btVector3 normalized() const
Return a normalized version of this vector.
Definition: btVector3.h:949
int m_objectType
Definition: btScalar.h:805