150 lines
5.3 KiB
C++
150 lines
5.3 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.
|
|
*/
|
|
|
|
#ifndef BT_JACOBIAN_ENTRY_H
|
|
#define BT_JACOBIAN_ENTRY_H
|
|
|
|
#include "LinearMath/btMatrix3x3.h"
|
|
|
|
//notes:
|
|
// Another memory optimization would be to store m_1MinvJt in the remaining 3 w components
|
|
// which makes the btJacobianEntry memory layout 16 bytes
|
|
// if you only are interested in angular part, just feed massInvA and massInvB zero
|
|
|
|
/// Jacobian entry is an abstraction that allows to describe constraints
|
|
/// it can be used in combination with a constraint solver
|
|
/// Can be used to relate the effect of an impulse to the constraint error
|
|
ATTRIBUTE_ALIGNED16(class)
|
|
btJacobianEntry
|
|
{
|
|
public:
|
|
btJacobianEntry(){};
|
|
//constraint between two different rigidbodies
|
|
btJacobianEntry(
|
|
const btMatrix3x3& world2A,
|
|
const btMatrix3x3& world2B,
|
|
const btVector3& rel_pos1, const btVector3& rel_pos2,
|
|
const btVector3& jointAxis,
|
|
const btVector3& inertiaInvA,
|
|
const btScalar massInvA,
|
|
const btVector3& inertiaInvB,
|
|
const btScalar massInvB)
|
|
: m_linearJointAxis(jointAxis)
|
|
{
|
|
m_aJ = world2A * (rel_pos1.cross(m_linearJointAxis));
|
|
m_bJ = world2B * (rel_pos2.cross(-m_linearJointAxis));
|
|
m_0MinvJt = inertiaInvA * m_aJ;
|
|
m_1MinvJt = inertiaInvB * m_bJ;
|
|
m_Adiag = massInvA + m_0MinvJt.dot(m_aJ) + massInvB + m_1MinvJt.dot(m_bJ);
|
|
|
|
btAssert(m_Adiag > btScalar(0.0));
|
|
}
|
|
|
|
//angular constraint between two different rigidbodies
|
|
btJacobianEntry(const btVector3& jointAxis,
|
|
const btMatrix3x3& world2A,
|
|
const btMatrix3x3& world2B,
|
|
const btVector3& inertiaInvA,
|
|
const btVector3& inertiaInvB)
|
|
: m_linearJointAxis(btVector3(btScalar(0.), btScalar(0.), btScalar(0.)))
|
|
{
|
|
m_aJ = world2A * jointAxis;
|
|
m_bJ = world2B * -jointAxis;
|
|
m_0MinvJt = inertiaInvA * m_aJ;
|
|
m_1MinvJt = inertiaInvB * m_bJ;
|
|
m_Adiag = m_0MinvJt.dot(m_aJ) + m_1MinvJt.dot(m_bJ);
|
|
|
|
btAssert(m_Adiag > btScalar(0.0));
|
|
}
|
|
|
|
//angular constraint between two different rigidbodies
|
|
btJacobianEntry(const btVector3& axisInA,
|
|
const btVector3& axisInB,
|
|
const btVector3& inertiaInvA,
|
|
const btVector3& inertiaInvB)
|
|
: m_linearJointAxis(btVector3(btScalar(0.), btScalar(0.), btScalar(0.))), m_aJ(axisInA), m_bJ(-axisInB)
|
|
{
|
|
m_0MinvJt = inertiaInvA * m_aJ;
|
|
m_1MinvJt = inertiaInvB * m_bJ;
|
|
m_Adiag = m_0MinvJt.dot(m_aJ) + m_1MinvJt.dot(m_bJ);
|
|
|
|
btAssert(m_Adiag > btScalar(0.0));
|
|
}
|
|
|
|
//constraint on one rigidbody
|
|
btJacobianEntry(
|
|
const btMatrix3x3& world2A,
|
|
const btVector3& rel_pos1, const btVector3& rel_pos2,
|
|
const btVector3& jointAxis,
|
|
const btVector3& inertiaInvA,
|
|
const btScalar massInvA)
|
|
: m_linearJointAxis(jointAxis)
|
|
{
|
|
m_aJ = world2A * (rel_pos1.cross(jointAxis));
|
|
m_bJ = world2A * (rel_pos2.cross(-jointAxis));
|
|
m_0MinvJt = inertiaInvA * m_aJ;
|
|
m_1MinvJt = btVector3(btScalar(0.), btScalar(0.), btScalar(0.));
|
|
m_Adiag = massInvA + m_0MinvJt.dot(m_aJ);
|
|
|
|
btAssert(m_Adiag > btScalar(0.0));
|
|
}
|
|
|
|
btScalar getDiagonal() const { return m_Adiag; }
|
|
|
|
// for two constraints on the same rigidbody (for example vehicle friction)
|
|
btScalar getNonDiagonal(const btJacobianEntry& jacB, const btScalar massInvA) const
|
|
{
|
|
const btJacobianEntry& jacA = *this;
|
|
btScalar lin = massInvA * jacA.m_linearJointAxis.dot(jacB.m_linearJointAxis);
|
|
btScalar ang = jacA.m_0MinvJt.dot(jacB.m_aJ);
|
|
return lin + ang;
|
|
}
|
|
|
|
// for two constraints on sharing two same rigidbodies (for example two contact points between two rigidbodies)
|
|
btScalar getNonDiagonal(const btJacobianEntry& jacB, const btScalar massInvA, const btScalar massInvB) const
|
|
{
|
|
const btJacobianEntry& jacA = *this;
|
|
btVector3 lin = jacA.m_linearJointAxis * jacB.m_linearJointAxis;
|
|
btVector3 ang0 = jacA.m_0MinvJt * jacB.m_aJ;
|
|
btVector3 ang1 = jacA.m_1MinvJt * jacB.m_bJ;
|
|
btVector3 lin0 = massInvA * lin;
|
|
btVector3 lin1 = massInvB * lin;
|
|
btVector3 sum = ang0 + ang1 + lin0 + lin1;
|
|
return sum[0] + sum[1] + sum[2];
|
|
}
|
|
|
|
btScalar getRelativeVelocity(const btVector3& linvelA, const btVector3& angvelA, const btVector3& linvelB, const btVector3& angvelB)
|
|
{
|
|
btVector3 linrel = linvelA - linvelB;
|
|
btVector3 angvela = angvelA * m_aJ;
|
|
btVector3 angvelb = angvelB * m_bJ;
|
|
linrel *= m_linearJointAxis;
|
|
angvela += angvelb;
|
|
angvela += linrel;
|
|
btScalar rel_vel2 = angvela[0] + angvela[1] + angvela[2];
|
|
return rel_vel2 + SIMD_EPSILON;
|
|
}
|
|
//private:
|
|
|
|
btVector3 m_linearJointAxis;
|
|
btVector3 m_aJ;
|
|
btVector3 m_bJ;
|
|
btVector3 m_0MinvJt;
|
|
btVector3 m_1MinvJt;
|
|
//Optimization: can be stored in the w/last component of one of the vectors
|
|
btScalar m_Adiag;
|
|
};
|
|
|
|
#endif //BT_JACOBIAN_ENTRY_H
|