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source: code/branches/physics/src/bullet/BulletDynamics/ConstraintSolver/btPoint2PointConstraint.cpp @ 1963

Last change on this file since 1963 was 1963, checked in by rgrieder, 15 years ago

Added Bullet physics engine.

  • Property svn:eol-style set to native
File size: 4.1 KB
Line 
1/*
2Bullet Continuous Collision Detection and Physics Library
3Copyright (c) 2003-2006 Erwin Coumans  http://continuousphysics.com/Bullet/
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
17#include "btPoint2PointConstraint.h"
18#include "BulletDynamics/Dynamics/btRigidBody.h"
19#include <new>
20
21
22
23btPoint2PointConstraint::btPoint2PointConstraint()
24:btTypedConstraint(POINT2POINT_CONSTRAINT_TYPE)
25{
26}
27
28btPoint2PointConstraint::btPoint2PointConstraint(btRigidBody& rbA,btRigidBody& rbB, const btVector3& pivotInA,const btVector3& pivotInB)
29:btTypedConstraint(POINT2POINT_CONSTRAINT_TYPE,rbA,rbB),m_pivotInA(pivotInA),m_pivotInB(pivotInB)
30{
31
32}
33
34
35btPoint2PointConstraint::btPoint2PointConstraint(btRigidBody& rbA,const btVector3& pivotInA)
36:btTypedConstraint(POINT2POINT_CONSTRAINT_TYPE,rbA),m_pivotInA(pivotInA),m_pivotInB(rbA.getCenterOfMassTransform()(pivotInA))
37{
38       
39}
40
41void    btPoint2PointConstraint::buildJacobian()
42{
43        m_appliedImpulse = btScalar(0.);
44
45        btVector3       normal(0,0,0);
46
47        for (int i=0;i<3;i++)
48        {
49                normal[i] = 1;
50                new (&m_jac[i]) btJacobianEntry(
51                        m_rbA.getCenterOfMassTransform().getBasis().transpose(),
52                        m_rbB.getCenterOfMassTransform().getBasis().transpose(),
53                        m_rbA.getCenterOfMassTransform()*m_pivotInA - m_rbA.getCenterOfMassPosition(),
54                        m_rbB.getCenterOfMassTransform()*m_pivotInB - m_rbB.getCenterOfMassPosition(),
55                        normal,
56                        m_rbA.getInvInertiaDiagLocal(),
57                        m_rbA.getInvMass(),
58                        m_rbB.getInvInertiaDiagLocal(),
59                        m_rbB.getInvMass());
60                normal[i] = 0;
61        }
62
63}
64
65void    btPoint2PointConstraint::solveConstraint(btScalar       timeStep)
66{
67        btVector3 pivotAInW = m_rbA.getCenterOfMassTransform()*m_pivotInA;
68        btVector3 pivotBInW = m_rbB.getCenterOfMassTransform()*m_pivotInB;
69
70
71        btVector3 normal(0,0,0);
72       
73
74//      btVector3 angvelA = m_rbA.getCenterOfMassTransform().getBasis().transpose() * m_rbA.getAngularVelocity();
75//      btVector3 angvelB = m_rbB.getCenterOfMassTransform().getBasis().transpose() * m_rbB.getAngularVelocity();
76
77        for (int i=0;i<3;i++)
78        {               
79                normal[i] = 1;
80                btScalar jacDiagABInv = btScalar(1.) / m_jac[i].getDiagonal();
81
82                btVector3 rel_pos1 = pivotAInW - m_rbA.getCenterOfMassPosition(); 
83                btVector3 rel_pos2 = pivotBInW - m_rbB.getCenterOfMassPosition();
84                //this jacobian entry could be re-used for all iterations
85               
86                btVector3 vel1 = m_rbA.getVelocityInLocalPoint(rel_pos1);
87                btVector3 vel2 = m_rbB.getVelocityInLocalPoint(rel_pos2);
88                btVector3 vel = vel1 - vel2;
89               
90                btScalar rel_vel;
91                rel_vel = normal.dot(vel);
92
93        /*
94                //velocity error (first order error)
95                btScalar rel_vel = m_jac[i].getRelativeVelocity(m_rbA.getLinearVelocity(),angvelA,
96                                                                                                                m_rbB.getLinearVelocity(),angvelB);
97        */
98       
99                //positional error (zeroth order error)
100                btScalar depth = -(pivotAInW - pivotBInW).dot(normal); //this is the error projected on the normal
101               
102                btScalar impulse = depth*m_setting.m_tau/timeStep  * jacDiagABInv -  m_setting.m_damping * rel_vel * jacDiagABInv;
103
104                btScalar impulseClamp = m_setting.m_impulseClamp;
105                if (impulseClamp > 0)
106                {
107                        if (impulse < -impulseClamp) 
108                                impulse = -impulseClamp;
109                        if (impulse > impulseClamp) 
110                                impulse = impulseClamp;
111                }
112
113                m_appliedImpulse+=impulse;
114                btVector3 impulse_vector = normal * impulse;
115                m_rbA.applyImpulse(impulse_vector, pivotAInW - m_rbA.getCenterOfMassPosition());
116                m_rbB.applyImpulse(-impulse_vector, pivotBInW - m_rbB.getCenterOfMassPosition());
117               
118                normal[i] = 0;
119        }
120}
121
122void    btPoint2PointConstraint::updateRHS(btScalar     timeStep)
123{
124        (void)timeStep;
125
126}
127
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