| 1 | /* |
|---|
| 2 | Bullet Continuous Collision Detection and Physics Library |
|---|
| 3 | Copyright (c) 2003-2006 Erwin Coumans http://continuousphysics.com/Bullet/ |
|---|
| 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 | |
|---|
| 16 | #ifndef JACOBIAN_ENTRY_H |
|---|
| 17 | #define JACOBIAN_ENTRY_H |
|---|
| 18 | |
|---|
| 19 | #include "LinearMath/btVector3.h" |
|---|
| 20 | #include "BulletDynamics/Dynamics/btRigidBody.h" |
|---|
| 21 | |
|---|
| 22 | |
|---|
| 23 | //notes: |
|---|
| 24 | // Another memory optimization would be to store m_1MinvJt in the remaining 3 w components |
|---|
| 25 | // which makes the btJacobianEntry memory layout 16 bytes |
|---|
| 26 | // if you only are interested in angular part, just feed massInvA and massInvB zero |
|---|
| 27 | |
|---|
| 28 | /// Jacobian entry is an abstraction that allows to describe constraints |
|---|
| 29 | /// it can be used in combination with a constraint solver |
|---|
| 30 | /// Can be used to relate the effect of an impulse to the constraint error |
|---|
| 31 | class btJacobianEntry |
|---|
| 32 | { |
|---|
| 33 | public: |
|---|
| 34 | btJacobianEntry() {}; |
|---|
| 35 | //constraint between two different rigidbodies |
|---|
| 36 | btJacobianEntry( |
|---|
| 37 | const btMatrix3x3& world2A, |
|---|
| 38 | const btMatrix3x3& world2B, |
|---|
| 39 | const btVector3& rel_pos1,const btVector3& rel_pos2, |
|---|
| 40 | const btVector3& jointAxis, |
|---|
| 41 | const btVector3& inertiaInvA, |
|---|
| 42 | const btScalar massInvA, |
|---|
| 43 | const btVector3& inertiaInvB, |
|---|
| 44 | const btScalar massInvB) |
|---|
| 45 | :m_linearJointAxis(jointAxis) |
|---|
| 46 | { |
|---|
| 47 | m_aJ = world2A*(rel_pos1.cross(m_linearJointAxis)); |
|---|
| 48 | m_bJ = world2B*(rel_pos2.cross(-m_linearJointAxis)); |
|---|
| 49 | m_0MinvJt = inertiaInvA * m_aJ; |
|---|
| 50 | m_1MinvJt = inertiaInvB * m_bJ; |
|---|
| 51 | m_Adiag = massInvA + m_0MinvJt.dot(m_aJ) + massInvB + m_1MinvJt.dot(m_bJ); |
|---|
| 52 | |
|---|
| 53 | btAssert(m_Adiag > btScalar(0.0)); |
|---|
| 54 | } |
|---|
| 55 | |
|---|
| 56 | //angular constraint between two different rigidbodies |
|---|
| 57 | btJacobianEntry(const btVector3& jointAxis, |
|---|
| 58 | const btMatrix3x3& world2A, |
|---|
| 59 | const btMatrix3x3& world2B, |
|---|
| 60 | const btVector3& inertiaInvA, |
|---|
| 61 | const btVector3& inertiaInvB) |
|---|
| 62 | :m_linearJointAxis(btVector3(btScalar(0.),btScalar(0.),btScalar(0.))) |
|---|
| 63 | { |
|---|
| 64 | m_aJ= world2A*jointAxis; |
|---|
| 65 | m_bJ = world2B*-jointAxis; |
|---|
| 66 | m_0MinvJt = inertiaInvA * m_aJ; |
|---|
| 67 | m_1MinvJt = inertiaInvB * m_bJ; |
|---|
| 68 | m_Adiag = m_0MinvJt.dot(m_aJ) + m_1MinvJt.dot(m_bJ); |
|---|
| 69 | |
|---|
| 70 | btAssert(m_Adiag > btScalar(0.0)); |
|---|
| 71 | } |
|---|
| 72 | |
|---|
| 73 | //angular constraint between two different rigidbodies |
|---|
| 74 | btJacobianEntry(const btVector3& axisInA, |
|---|
| 75 | const btVector3& axisInB, |
|---|
| 76 | const btVector3& inertiaInvA, |
|---|
| 77 | const btVector3& inertiaInvB) |
|---|
| 78 | : m_linearJointAxis(btVector3(btScalar(0.),btScalar(0.),btScalar(0.))) |
|---|
| 79 | , m_aJ(axisInA) |
|---|
| 80 | , m_bJ(-axisInB) |
|---|
| 81 | { |
|---|
| 82 | m_0MinvJt = inertiaInvA * m_aJ; |
|---|
| 83 | m_1MinvJt = inertiaInvB * m_bJ; |
|---|
| 84 | m_Adiag = m_0MinvJt.dot(m_aJ) + m_1MinvJt.dot(m_bJ); |
|---|
| 85 | |
|---|
| 86 | btAssert(m_Adiag > btScalar(0.0)); |
|---|
| 87 | } |
|---|
| 88 | |
|---|
| 89 | //constraint on one rigidbody |
|---|
| 90 | btJacobianEntry( |
|---|
| 91 | const btMatrix3x3& world2A, |
|---|
| 92 | const btVector3& rel_pos1,const btVector3& rel_pos2, |
|---|
| 93 | const btVector3& jointAxis, |
|---|
| 94 | const btVector3& inertiaInvA, |
|---|
| 95 | const btScalar massInvA) |
|---|
| 96 | :m_linearJointAxis(jointAxis) |
|---|
| 97 | { |
|---|
| 98 | m_aJ= world2A*(rel_pos1.cross(jointAxis)); |
|---|
| 99 | m_bJ = world2A*(rel_pos2.cross(-jointAxis)); |
|---|
| 100 | m_0MinvJt = inertiaInvA * m_aJ; |
|---|
| 101 | m_1MinvJt = btVector3(btScalar(0.),btScalar(0.),btScalar(0.)); |
|---|
| 102 | m_Adiag = massInvA + m_0MinvJt.dot(m_aJ); |
|---|
| 103 | |
|---|
| 104 | btAssert(m_Adiag > btScalar(0.0)); |
|---|
| 105 | } |
|---|
| 106 | |
|---|
| 107 | btScalar getDiagonal() const { return m_Adiag; } |
|---|
| 108 | |
|---|
| 109 | // for two constraints on the same rigidbody (for example vehicle friction) |
|---|
| 110 | btScalar getNonDiagonal(const btJacobianEntry& jacB, const btScalar massInvA) const |
|---|
| 111 | { |
|---|
| 112 | const btJacobianEntry& jacA = *this; |
|---|
| 113 | btScalar lin = massInvA * jacA.m_linearJointAxis.dot(jacB.m_linearJointAxis); |
|---|
| 114 | btScalar ang = jacA.m_0MinvJt.dot(jacB.m_aJ); |
|---|
| 115 | return lin + ang; |
|---|
| 116 | } |
|---|
| 117 | |
|---|
| 118 | |
|---|
| 119 | |
|---|
| 120 | // for two constraints on sharing two same rigidbodies (for example two contact points between two rigidbodies) |
|---|
| 121 | btScalar getNonDiagonal(const btJacobianEntry& jacB,const btScalar massInvA,const btScalar massInvB) const |
|---|
| 122 | { |
|---|
| 123 | const btJacobianEntry& jacA = *this; |
|---|
| 124 | btVector3 lin = jacA.m_linearJointAxis * jacB.m_linearJointAxis; |
|---|
| 125 | btVector3 ang0 = jacA.m_0MinvJt * jacB.m_aJ; |
|---|
| 126 | btVector3 ang1 = jacA.m_1MinvJt * jacB.m_bJ; |
|---|
| 127 | btVector3 lin0 = massInvA * lin ; |
|---|
| 128 | btVector3 lin1 = massInvB * lin; |
|---|
| 129 | btVector3 sum = ang0+ang1+lin0+lin1; |
|---|
| 130 | return sum[0]+sum[1]+sum[2]; |
|---|
| 131 | } |
|---|
| 132 | |
|---|
| 133 | btScalar getRelativeVelocity(const btVector3& linvelA,const btVector3& angvelA,const btVector3& linvelB,const btVector3& angvelB) |
|---|
| 134 | { |
|---|
| 135 | btVector3 linrel = linvelA - linvelB; |
|---|
| 136 | btVector3 angvela = angvelA * m_aJ; |
|---|
| 137 | btVector3 angvelb = angvelB * m_bJ; |
|---|
| 138 | linrel *= m_linearJointAxis; |
|---|
| 139 | angvela += angvelb; |
|---|
| 140 | angvela += linrel; |
|---|
| 141 | btScalar rel_vel2 = angvela[0]+angvela[1]+angvela[2]; |
|---|
| 142 | return rel_vel2 + SIMD_EPSILON; |
|---|
| 143 | } |
|---|
| 144 | //private: |
|---|
| 145 | |
|---|
| 146 | btVector3 m_linearJointAxis; |
|---|
| 147 | btVector3 m_aJ; |
|---|
| 148 | btVector3 m_bJ; |
|---|
| 149 | btVector3 m_0MinvJt; |
|---|
| 150 | btVector3 m_1MinvJt; |
|---|
| 151 | //Optimization: can be stored in the w/last component of one of the vectors |
|---|
| 152 | btScalar m_Adiag; |
|---|
| 153 | |
|---|
| 154 | }; |
|---|
| 155 | |
|---|
| 156 | #endif //JACOBIAN_ENTRY_H |
|---|
