252 lines
8.0 KiB
C++
252 lines
8.0 KiB
C++
/*
|
|
Bullet Continuous Collision Detection and Physics Library
|
|
Copyright (c) 2003-2006 Erwin Coumans http://continuousphysics.com/Bullet/
|
|
|
|
This software is provided 'as-is', without any express or implied warranty.
|
|
In no event will the authors be held liable for any damages arising from the use of this software.
|
|
Permission is granted to anyone to use this software for any purpose,
|
|
including commercial applications, and to alter it and redistribute it freely,
|
|
subject to the following restrictions:
|
|
|
|
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.
|
|
2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
|
|
3. This notice may not be removed or altered from any source distribution.
|
|
*/
|
|
|
|
|
|
#include "btGeneric6DofConstraint.h"
|
|
#include "BulletDynamics/Dynamics/btRigidBody.h"
|
|
#include "BulletDynamics/Dynamics/btMassProps.h"
|
|
#include "LinearMath/btTransformUtil.h"
|
|
|
|
static const btScalar kSign[] = { 1.0f, -1.0f, 1.0f };
|
|
static const int kAxisA[] = { 1, 0, 0 };
|
|
static const int kAxisB[] = { 2, 2, 1 };
|
|
|
|
btGeneric6DofConstraint::btGeneric6DofConstraint()
|
|
{
|
|
}
|
|
|
|
btGeneric6DofConstraint::btGeneric6DofConstraint(btRigidBody& rbA, btRigidBody& rbB, const btTransform& frameInA, const btTransform& frameInB)
|
|
: btTypedConstraint(rbA, rbB)
|
|
, m_frameInA(frameInA)
|
|
, m_frameInB(frameInB)
|
|
{
|
|
//free means upper < lower,
|
|
//locked means upper == lower
|
|
//limited means upper > lower
|
|
//so start all locked
|
|
for (int i=0; i<6;++i)
|
|
{
|
|
m_lowerLimit[i] = 0.0f;
|
|
m_upperLimit[i] = 0.0f;
|
|
m_accumulatedImpulse[i] = 0.0f;
|
|
}
|
|
|
|
}
|
|
|
|
|
|
void btGeneric6DofConstraint::BuildJacobian()
|
|
{
|
|
btVector3 normal(0,0,0);
|
|
|
|
const btVector3& pivotInA = m_frameInA.getOrigin();
|
|
const btVector3& pivotInB = m_frameInB.getOrigin();
|
|
|
|
btVector3 pivotAInW = m_rbA.getCenterOfMassTransform() * m_frameInA.getOrigin();
|
|
btVector3 pivotBInW = m_rbB.getCenterOfMassTransform() * m_frameInB.getOrigin();
|
|
|
|
btVector3 rel_pos1 = pivotAInW - m_rbA.getCenterOfMassPosition();
|
|
btVector3 rel_pos2 = pivotBInW - m_rbB.getCenterOfMassPosition();
|
|
|
|
int i;
|
|
//linear part
|
|
for (i=0;i<3;i++)
|
|
{
|
|
if (isLimited(i))
|
|
{
|
|
normal[i] = 1;
|
|
|
|
// Create linear atom
|
|
new (&m_jacLinear[i]) btJacobianEntry(
|
|
m_rbA.getCenterOfMassTransform().getBasis().transpose(),
|
|
m_rbB.getCenterOfMassTransform().getBasis().transpose(),
|
|
m_rbA.getCenterOfMassTransform()*pivotInA - m_rbA.getCenterOfMassPosition(),
|
|
m_rbB.getCenterOfMassTransform()*pivotInB - m_rbB.getCenterOfMassPosition(),
|
|
normal,
|
|
m_rbA.getInvInertiaDiagLocal(),
|
|
m_rbA.getInvMass(),
|
|
m_rbB.getInvInertiaDiagLocal(),
|
|
m_rbB.getInvMass());
|
|
|
|
// Apply accumulated impulse
|
|
btVector3 impulse_vector = m_accumulatedImpulse[i] * normal;
|
|
|
|
m_rbA.applyImpulse( impulse_vector, rel_pos1);
|
|
m_rbB.applyImpulse(-impulse_vector, rel_pos2);
|
|
|
|
normal[i] = 0;
|
|
}
|
|
}
|
|
|
|
// angular part
|
|
for (i=0;i<3;i++)
|
|
{
|
|
if (isLimited(i+3))
|
|
{
|
|
btVector3 axisA = m_rbA.getCenterOfMassTransform().getBasis() * m_frameInA.getBasis().getColumn( kAxisA[i] );
|
|
btVector3 axisB = m_rbB.getCenterOfMassTransform().getBasis() * m_frameInB.getBasis().getColumn( kAxisB[i] );
|
|
|
|
// Dirk: This is IMO mathematically the correct way, but we should consider axisA and axisB being near parallel maybe
|
|
btVector3 axis = kSign[i] * axisA.cross(axisB);
|
|
|
|
// Create angular atom
|
|
new (&m_jacAng[i]) btJacobianEntry(axis,
|
|
m_rbA.getCenterOfMassTransform().getBasis().transpose(),
|
|
m_rbB.getCenterOfMassTransform().getBasis().transpose(),
|
|
m_rbA.getInvInertiaDiagLocal(),
|
|
m_rbB.getInvInertiaDiagLocal());
|
|
|
|
// Apply accumulated impulse
|
|
btVector3 impulse_vector = m_accumulatedImpulse[i + 3] * axis;
|
|
|
|
m_rbA.applyTorqueImpulse( impulse_vector);
|
|
m_rbB.applyTorqueImpulse(-impulse_vector);
|
|
}
|
|
}
|
|
}
|
|
|
|
void btGeneric6DofConstraint::SolveConstraint(btScalar timeStep)
|
|
{
|
|
btScalar tau = 0.1f;
|
|
btScalar damping = 1.0f;
|
|
|
|
btVector3 pivotAInW = m_rbA.getCenterOfMassTransform() * m_frameInA.getOrigin();
|
|
btVector3 pivotBInW = m_rbB.getCenterOfMassTransform() * m_frameInB.getOrigin();
|
|
|
|
btVector3 rel_pos1 = pivotAInW - m_rbA.getCenterOfMassPosition();
|
|
btVector3 rel_pos2 = pivotBInW - m_rbB.getCenterOfMassPosition();
|
|
|
|
btVector3 normal(0,0,0);
|
|
int i;
|
|
|
|
// linear
|
|
for (i=0;i<3;i++)
|
|
{
|
|
if (isLimited(i))
|
|
{
|
|
btVector3 angvelA = m_rbA.getCenterOfMassTransform().getBasis().transpose() * m_rbA.getAngularVelocity();
|
|
btVector3 angvelB = m_rbB.getCenterOfMassTransform().getBasis().transpose() * m_rbB.getAngularVelocity();
|
|
|
|
|
|
normal[i] = 1;
|
|
btScalar jacDiagABInv = 1.f / m_jacLinear[i].getDiagonal();
|
|
|
|
//velocity error (first order error)
|
|
btScalar rel_vel = m_jacLinear[i].getRelativeVelocity(m_rbA.getLinearVelocity(),angvelA,
|
|
m_rbB.getLinearVelocity(),angvelB);
|
|
|
|
//positional error (zeroth order error)
|
|
btScalar depth = -(pivotAInW - pivotBInW).dot(normal);
|
|
|
|
btScalar impulse = (tau*depth/timeStep - damping*rel_vel) * jacDiagABInv;
|
|
m_accumulatedImpulse[i] += impulse;
|
|
|
|
btVector3 impulse_vector = normal * impulse;
|
|
m_rbA.applyImpulse( impulse_vector, rel_pos1);
|
|
m_rbB.applyImpulse(-impulse_vector, rel_pos2);
|
|
|
|
normal[i] = 0;
|
|
}
|
|
}
|
|
|
|
// angular
|
|
for (i=0;i<3;i++)
|
|
{
|
|
if (isLimited(i+3))
|
|
{
|
|
btVector3 angvelA = m_rbA.getCenterOfMassTransform().getBasis().transpose() * m_rbA.getAngularVelocity();
|
|
btVector3 angvelB = m_rbB.getCenterOfMassTransform().getBasis().transpose() * m_rbB.getAngularVelocity();
|
|
|
|
btScalar jacDiagABInv = 1.f / m_jacAng[i].getDiagonal();
|
|
|
|
//velocity error (first order error)
|
|
btScalar rel_vel = m_jacAng[i].getRelativeVelocity(m_rbA.getLinearVelocity(),angvelA,
|
|
m_rbB.getLinearVelocity(),angvelB);
|
|
|
|
//positional error (zeroth order error)
|
|
btVector3 axisA = m_rbA.getCenterOfMassTransform().getBasis() * m_frameInA.getBasis().getColumn( kAxisA[i] );
|
|
btVector3 axisB = m_rbB.getCenterOfMassTransform().getBasis() * m_frameInB.getBasis().getColumn( kAxisB[i] );
|
|
|
|
btScalar rel_pos = kSign[i] * axisA.dot(axisB);
|
|
|
|
//impulse
|
|
btScalar impulse = -(tau*rel_pos/timeStep + damping*rel_vel) * jacDiagABInv;
|
|
m_accumulatedImpulse[i + 3] += impulse;
|
|
|
|
// Dirk: Not needed - we could actually project onto Jacobian entry here (same as above)
|
|
btVector3 axis = kSign[i] * axisA.cross(axisB);
|
|
btVector3 impulse_vector = axis * impulse;
|
|
|
|
m_rbA.applyTorqueImpulse( impulse_vector);
|
|
m_rbB.applyTorqueImpulse(-impulse_vector);
|
|
}
|
|
}
|
|
}
|
|
|
|
void btGeneric6DofConstraint::UpdateRHS(btScalar timeStep)
|
|
{
|
|
|
|
}
|
|
|
|
btScalar btGeneric6DofConstraint::ComputeAngle(int axis) const
|
|
{
|
|
btScalar angle;
|
|
|
|
switch (axis)
|
|
{
|
|
case 0:
|
|
{
|
|
btVector3 v1 = m_rbA.getCenterOfMassTransform().getBasis() * m_frameInA.getBasis().getColumn(1);
|
|
btVector3 v2 = m_rbB.getCenterOfMassTransform().getBasis() * m_frameInB.getBasis().getColumn(1);
|
|
btVector3 w2 = m_rbB.getCenterOfMassTransform().getBasis() * m_frameInB.getBasis().getColumn(2);
|
|
|
|
btScalar s = v1.dot(w2);
|
|
btScalar c = v1.dot(v2);
|
|
|
|
angle = btAtan2( s, c );
|
|
}
|
|
break;
|
|
|
|
case 1:
|
|
{
|
|
btVector3 w1 = m_rbA.getCenterOfMassTransform().getBasis() * m_frameInA.getBasis().getColumn(2);
|
|
btVector3 w2 = m_rbB.getCenterOfMassTransform().getBasis() * m_frameInB.getBasis().getColumn(2);
|
|
btVector3 u2 = m_rbB.getCenterOfMassTransform().getBasis() * m_frameInB.getBasis().getColumn(0);
|
|
|
|
btScalar s = w1.dot(u2);
|
|
btScalar c = w1.dot(w2);
|
|
|
|
angle = btAtan2( s, c );
|
|
}
|
|
break;
|
|
|
|
case 2:
|
|
{
|
|
btVector3 u1 = m_rbA.getCenterOfMassTransform().getBasis() * m_frameInA.getBasis().getColumn(0);
|
|
btVector3 u2 = m_rbB.getCenterOfMassTransform().getBasis() * m_frameInB.getBasis().getColumn(0);
|
|
btVector3 v2 = m_rbB.getCenterOfMassTransform().getBasis() * m_frameInB.getBasis().getColumn(1);
|
|
|
|
btScalar s = u1.dot(v2);
|
|
btScalar c = u1.dot(u2);
|
|
|
|
angle = btAtan2( s, c );
|
|
}
|
|
break;
|
|
default: assert ( 0 ) ; break ;
|
|
}
|
|
|
|
return angle;
|
|
}
|
|
|