Blender  V3.3
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.
7 Permission is granted to anyone to use this software for any purpose,
8 including commercial applications, and to alter it and redistribute it freely,
9 subject to the following restrictions:
10 
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 
21  : btGeneric6DofConstraint(rbA, rbB, frameInA, frameInB, useLinearReferenceFrameA)
22 {
23  init();
24 }
25 
27  : btGeneric6DofConstraint(rbB, frameInB, useLinearReferenceFrameB)
28 {
29  init();
30 }
31 
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 
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 
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 
169 }
virtual void getInfo2(btConstraintInfo2 *info)
void setDamping(btScalar damping)
btFixedConstraint btRigidBody & rbB
btFixedConstraint btRigidBody const btTransform & frameInA
btFixedConstraint btRigidBody const btTransform const btTransform & frameInB
btVector3 m_calculatedLinearDiff
btRotationalLimitMotor m_angularLimits[3]
btGeneric6DofConstraint(btRigidBody &rbA, btRigidBody &rbB, const btTransform &frameInA, const btTransform &frameInB, bool useLinearReferenceFrameA)
void setAxis(const btVector3 &axis1, const btVector3 &axis2)
btTranslationalLimitMotor m_linearLimits
btTransform m_frameInB
void calculateTransforms(const btTransform &transA, const btTransform &transB)
Calcs global transform of the offsets.
btVector3 m_calculatedAxisAngleDiff
void setStiffness(int index, btScalar stiffness, bool limitIfNeeded=true)
void enableSpring(int index, bool onOff)
btScalar m_equilibriumPoint[6]
btScalar m_springDamping[6]
void internalUpdateSprings(btConstraintInfo2 *info)
btScalar m_springStiffness[6]
btGeneric6DofSpringConstraint(btRigidBody &rbA, btRigidBody &rbB, const btTransform &frameInA, const btTransform &frameInB, bool useLinearReferenceFrameA)
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:314
SIMD_FORCE_INLINE btScalar btFabs(btScalar x)
Definition: btScalar.h:497
#define btAssert(x)
Definition: btScalar.h:295
btTransform m_frameInA
btTransform
The btTransform class supports rigid transforms with only translation and rotation and no scaling/she...
Definition: btTransform.h:30
btRigidBody & m_rbA
btRigidBody & m_rbB
@ D6_SPRING_CONSTRAINT_TYPE
btVector3
btVector3 can be used to represent 3D points and vectors. It has an un-used w component to suit 16-by...
Definition: btVector3.h:82
const btTransform & getCenterOfMassTransform() const
Definition: btRigidBody.h:429
btScalar m_targetVelocity
target motor velocity
btScalar m_maxMotorForce
max force on motor
btVector3 m_maxMotorForce
max force on motor
btVector3 m_targetVelocity
target motor velocity