void pfxSetupBallJoint(
PfxJoint &joint,
const PfxRigidState &stateA,
const PfxRigidState &stateB,
PfxSolverBody &solverBodyA,
PfxSolverBody &solverBodyB,
PfxFloat timeStep
)
{
PfxVector3 rA = rotate(solverBodyA.m_orientation,joint.m_anchorA);
PfxVector3 rB = rotate(solverBodyB.m_orientation,joint.m_anchorB);
PfxVector3 vA = stateA.getLinearVelocity() + cross(stateA.getAngularVelocity(),rA);
PfxVector3 vB = stateB.getLinearVelocity() + cross(stateB.getAngularVelocity(),rB);
PfxVector3 vAB = vA-vB;
PfxVector3 distance = (stateA.getPosition() + rA) - (stateB.getPosition() + rB);
PfxMatrix3 worldFrameA,worldFrameB;
worldFrameA = PfxMatrix3(solverBodyA.m_orientation) * joint.m_frameA;
worldFrameB = PfxMatrix3(solverBodyB.m_orientation) * joint.m_frameB;
// Linear Constraint
PfxMatrix3 K = PfxMatrix3::scale(PfxVector3(solverBodyA.m_massInv + solverBodyB.m_massInv)) -
crossMatrix(rA) * solverBodyA.m_inertiaInv * crossMatrix(rA) -
crossMatrix(rB) * solverBodyB.m_inertiaInv * crossMatrix(rB);
for(int c=0;c<3;c++) {
PfxJointConstraint &jointConstraint = joint.m_constraints[c];
PfxConstraintRow &constraint = jointConstraint.m_constraintRow;
PfxVector3 normal = worldFrameA[c];
PfxFloat posErr = dot(distance,-normal);
PfxFloat lowerLimit = -jointConstraint.m_maxImpulse;
PfxFloat upperLimit = jointConstraint.m_maxImpulse;
PfxFloat velocityAmp = 1.0f;
pfxCalcLinearLimit(jointConstraint,posErr,velocityAmp,lowerLimit,upperLimit);
PfxFloat denom = dot(K*normal,normal);
constraint.m_rhs = -velocityAmp*dot(vAB,normal);
constraint.m_rhs -= (jointConstraint.m_bias * (-posErr)) / timeStep;
constraint.m_rhs *= jointConstraint.m_weight/denom;
constraint.m_jacDiagInv = jointConstraint.m_weight*velocityAmp/denom;
constraint.m_lowerLimit = lowerLimit;
constraint.m_upperLimit = upperLimit;
pfxStoreVector3(normal,constraint.m_normal);
}
}
void pfxSetupContactConstraint(
PfxConstraintRow &constraintResponse,
PfxConstraintRow &constraintFriction1,
PfxConstraintRow &constraintFriction2,
PfxFloat penetrationDepth,
PfxFloat restitution,
PfxFloat friction,
const PfxVector3 &contactNormal,
const PfxVector3 &contactPointA,
const PfxVector3 &contactPointB,
const PfxRigidState &stateA,
const PfxRigidState &stateB,
PfxSolverBody &solverBodyA,
PfxSolverBody &solverBodyB,
PfxFloat separateBias,
PfxFloat timeStep
)
{
(void)friction;
PfxVector3 rA = rotate(solverBodyA.m_orientation,contactPointA);
PfxVector3 rB = rotate(solverBodyB.m_orientation,contactPointB);
PfxFloat massInvA = solverBodyA.m_massInv;
PfxFloat massInvB = solverBodyB.m_massInv;
PfxMatrix3 inertiaInvA = solverBodyA.m_inertiaInv;
PfxMatrix3 inertiaInvB = solverBodyB.m_inertiaInv;
if(solverBodyA.m_motionType == kPfxMotionTypeOneWay) {
massInvB = 0.0f;
inertiaInvB = PfxMatrix3(0.0f);
}
if(solverBodyB.m_motionType == kPfxMotionTypeOneWay) {
massInvA = 0.0f;
inertiaInvA = PfxMatrix3(0.0f);
}
PfxMatrix3 K = PfxMatrix3::scale(PfxVector3(massInvA + massInvB)) -
crossMatrix(rA) * inertiaInvA * crossMatrix(rA) -
crossMatrix(rB) * inertiaInvB * crossMatrix(rB);
PfxVector3 vA = stateA.getLinearVelocity() + cross(stateA.getAngularVelocity(),rA);
PfxVector3 vB = stateB.getLinearVelocity() + cross(stateB.getAngularVelocity(),rB);
PfxVector3 vAB = vA-vB;
PfxVector3 tangent1,tangent2;
pfxGetPlaneSpace(contactNormal,tangent1,tangent2);
// Contact Constraint
{
PfxVector3 normal = contactNormal;
PfxFloat denom = dot(K*normal,normal);
constraintResponse.m_rhs = -(1.0f+restitution)*dot(vAB,normal); // velocity error
constraintResponse.m_rhs -= (separateBias * SCE_PFX_MIN(0.0f,penetrationDepth+SCE_PFX_CONTACT_SLOP)) / timeStep; // position error
constraintResponse.m_rhs /= denom;
constraintResponse.m_jacDiagInv = 1.0f/denom;
constraintResponse.m_lowerLimit = 0.0f;
constraintResponse.m_upperLimit = SCE_PFX_FLT_MAX;
pfxStoreVector3(normal,constraintResponse.m_normal);
}
// Friction Constraint 1
{
PfxVector3 normal = tangent1;
PfxFloat denom = dot(K*normal,normal);
constraintFriction1.m_jacDiagInv = 1.0f/denom;
constraintFriction1.m_rhs = -dot(vAB,normal);
constraintFriction1.m_rhs *= constraintFriction1.m_jacDiagInv;
constraintFriction1.m_lowerLimit = 0.0f;
constraintFriction1.m_upperLimit = SCE_PFX_FLT_MAX;
pfxStoreVector3(normal,constraintFriction1.m_normal);
}
// Friction Constraint 2
{
PfxVector3 normal = tangent2;
PfxFloat denom = dot(K*normal,normal);
constraintFriction2.m_jacDiagInv = 1.0f/denom;
constraintFriction2.m_rhs = -dot(vAB,normal);
constraintFriction2.m_rhs *= constraintFriction2.m_jacDiagInv;
constraintFriction2.m_lowerLimit = 0.0f;
constraintFriction2.m_upperLimit = SCE_PFX_FLT_MAX;
pfxStoreVector3(normal,constraintFriction2.m_normal);
}
}