forked from bartvdbraak/blender
130 lines
4.1 KiB
C++
130 lines
4.1 KiB
C++
/*
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* Copyright (c) 2005 Erwin Coumans http://www.erwincoumans.com
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*
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* Permission to use, copy, modify, distribute and sell this software
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* and its documentation for any purpose is hereby granted without fee,
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* provided that the above copyright notice appear in all copies.
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* Erwin Coumans makes no representations about the suitability
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* of this software for any purpose.
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* It is provided "as is" without express or implied warranty.
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*/
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#ifndef JACOBIAN_ENTRY_H
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#define JACOBIAN_ENTRY_H
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#include "SimdVector3.h"
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#include "Dynamics/RigidBody.h"
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//notes:
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// Another memory optimization would be to store m_MbJ in the remaining 3 w components
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// which makes the JacobianEntry memory layout 16 bytes
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// if you only are interested in angular part, just feed massInvA and massInvB zero
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/// Jacobian entry is an abstraction that allows to describe constraints
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/// it can be used in combination with a constraint solver
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/// Can be used to relate the effect of an impulse to the constraint error
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class JacobianEntry
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{
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public:
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JacobianEntry() {};
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//constraint between two different rigidbodies
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JacobianEntry(
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const SimdMatrix3x3& world2A,
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const SimdMatrix3x3& world2B,
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const SimdVector3& rel_pos1,const SimdVector3& rel_pos2,
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const SimdVector3& normal,
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const SimdVector3& inertiaInvA,
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const SimdScalar massInvA,
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const SimdVector3& inertiaInvB,
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const SimdScalar massInvB)
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:m_normalAxis(normal)
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{
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m_aJ = world2A*(rel_pos1.cross(normal));
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m_bJ = world2B*(rel_pos2.cross(normal));
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m_MaJ = inertiaInvA * m_aJ;
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m_MbJ = inertiaInvB * m_bJ;
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m_jacDiagAB = massInvA + m_MaJ.dot(m_aJ) + massInvB + m_MbJ.dot(m_bJ);
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}
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//angular constraint between two different rigidbodies
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JacobianEntry(const SimdVector3& normal,
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const SimdMatrix3x3& world2A,
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const SimdMatrix3x3& world2B,
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const SimdVector3& inertiaInvA,
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const SimdVector3& inertiaInvB)
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:m_normalAxis(normal)
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{
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m_aJ= world2A*normal;
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m_bJ = world2B*-normal;
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m_MaJ = inertiaInvA * m_aJ;
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m_MbJ = inertiaInvB * m_bJ;
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m_jacDiagAB = m_MaJ.dot(m_aJ) + m_MbJ.dot(m_bJ);
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}
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//constraint on one rigidbody
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JacobianEntry(
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const SimdMatrix3x3& world2A,
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const SimdVector3& rel_pos1,const SimdVector3& rel_pos2,
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const SimdVector3& normal,
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const SimdVector3& inertiaInvA,
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const SimdScalar massInvA)
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:m_normalAxis(normal)
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{
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m_aJ= world2A*(rel_pos1.cross(normal));
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m_bJ = world2A*(rel_pos2.cross(normal));
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m_MaJ = inertiaInvA * m_aJ;
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m_MbJ = SimdVector3(0.f,0.f,0.f);
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m_jacDiagAB = massInvA + m_MaJ.dot(m_aJ);
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}
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SimdScalar getDiagonal() const { return m_jacDiagAB; }
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// for two constraints on the same rigidbody (for example vehicle friction)
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SimdScalar getNonDiagonal(const JacobianEntry& jacB, const SimdScalar massInvA) const
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{
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const JacobianEntry& jacA = *this;
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SimdScalar lin = massInvA * jacA.m_normalAxis.dot(jacB.m_normalAxis);
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SimdScalar ang = jacA.m_MaJ.dot(jacB.m_aJ);
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return lin + ang;
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}
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// for two constraints on sharing two same rigidbodies (for example two contact points between two rigidbodies)
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SimdScalar getNonDiagonal(const JacobianEntry& jacB,const SimdScalar massInvA,const SimdScalar massInvB) const
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{
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const JacobianEntry& jacA = *this;
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SimdVector3 lin = jacA.m_normalAxis * jacB.m_normalAxis;
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SimdVector3 ang0 = jacA.m_MaJ * jacB.m_aJ;
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SimdVector3 ang1 = jacA.m_MbJ * jacB.m_bJ;
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SimdVector3 lin0 = massInvA * lin ;
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SimdVector3 lin1 = massInvB * lin;
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SimdVector3 sum = ang0+ang1+lin0+lin1;
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return sum[0]+sum[1]+sum[2];
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}
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SimdScalar getRelativeVelocity(const SimdVector3& linvelA,const SimdVector3& angvelA,const SimdVector3& linvelB,const SimdVector3& angvelB)
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{
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SimdVector3 linrel = linvelA - linvelB;
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SimdVector3 angvela = angvelA * m_aJ;
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SimdVector3 angvelb = angvelB * m_bJ;
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linrel *= m_normalAxis;
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angvela += angvelb;
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angvela += linrel;
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SimdScalar rel_vel2 = angvela[0]+angvela[1]+angvela[2];
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return rel_vel2 + SIMD_EPSILON;
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}
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//private:
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SimdVector3 m_normalAxis;
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SimdVector3 m_aJ;
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SimdVector3 m_bJ;
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SimdVector3 m_MaJ;
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SimdVector3 m_MbJ;
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//Optimization: can be stored in the w/last component of one of the vectors
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SimdScalar m_jacDiagAB;
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};
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#endif //JACOBIAN_ENTRY_H
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