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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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.
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15 
19 
20 
21 btGeneric6DofSpringConstraint::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 
28 btGeneric6DofSpringConstraint::btGeneric6DofSpringConstraint(btRigidBody& rbB, const btTransform& frameInB, bool useLinearReferenceFrameB)
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;
42  m_equilibriumPoint[i] = btScalar(0.f);
43  m_springStiffness[i] = btScalar(0.f);
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  {
106  m_equilibriumPoint[index] = m_calculatedAxisAngleDiff[index - 3];
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;
135  }
136  }
137  for(i = 0; i < 3; i++)
138  {
139  if(m_springEnabled[i + 3])
140  {
141  // get current position of constraint
142  btScalar currPos = m_calculatedAxisAngleDiff[i];
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;
150  }
151  }
152 }
153 
154 
156 {
157  // this will be called by constraint solver at the constraint setup stage
158  // set current motor parameters
159  internalUpdateSprings(info);
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 
void internalUpdateSprings(btConstraintInfo2 *info)
btGeneric6DofSpringConstraint(btRigidBody &rbA, btRigidBody &rbB, const btTransform &frameInA, const btTransform &frameInB, bool useLinearReferenceFrameA)
btGeneric6DofConstraint between two rigidbodies each with a pivotpoint that descibes the axis locatio...
btVector3 m_targetVelocity
target motor velocity
void setIdentity()
Set this transformation to the identity.
Definition: btTransform.h:172
#define btAssert(x)
Definition: btScalar.h:131
void setStiffness(int index, btScalar stiffness)
virtual void getInfo2(btConstraintInfo2 *info)
internal method used by the constraint solver, don&#39;t use them directly
const btTransform & getCenterOfMassTransform() const
Definition: btRigidBody.h:359
void setDamping(int index, btScalar damping)
btTranslationalLimitMotor m_linearLimits
Linear_Limit_parameters.
btVector3 cross(const btVector3 &v) const
Return the cross product between this and another vector.
Definition: btVector3.h:389
btScalar m_targetVelocity
target motor velocity
btMatrix3x3 & getBasis()
Return the basis matrix for the rotation.
Definition: btTransform.h:112
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:62
btTransform inverse() const
Return the inverse of this transform.
Definition: btTransform.h:188
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:83
btTransform m_frameInA
relative_frames
virtual void getInfo2(btConstraintInfo2 *info)
internal method used by the constraint solver, don&#39;t use them directly
The btTransform class supports rigid transforms with only translation and rotation and no scaling/she...
Definition: btTransform.h:34
btRotationalLimitMotor m_angularLimits[3]
hinge_parameters
btVector3 normalized() const
Return a normalized version of this vector.
Definition: btVector3.h:966
btTransform m_frameInB
the constraint space w.r.t body B
btVector3 m_maxMotorForce
max force on motor
virtual void setAxis(const btVector3 &axis1, const btVector3 &axis2)
btScalar m_maxMotorForce
max force on motor
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:292
int m_objectType
Definition: btScalar.h:783
btScalar btFabs(btScalar x)
Definition: btScalar.h:475