void btHingeConstraint::solveConstraint(btScalar timeStep)
{
btVector3 pivotAInW = m_rbA.getCenterOfMassTransform()*m_rbAFrame.getOrigin();
btVector3 pivotBInW = m_rbB.getCenterOfMassTransform()*m_rbBFrame.getOrigin();
btScalar tau = btScalar(0.3);
//linear part
if (!m_angularOnly)
{
btVector3 rel_pos1 = pivotAInW - m_rbA.getCenterOfMassPosition();
btVector3 rel_pos2 = pivotBInW - m_rbB.getCenterOfMassPosition();
btVector3 vel1 = m_rbA.getVelocityInLocalPoint(rel_pos1);
btVector3 vel2 = m_rbB.getVelocityInLocalPoint(rel_pos2);
btVector3 vel = vel1 - vel2;
for (int i=0;i<3;i++)
{
const btVector3& normal = m_jac[i].m_linearJointAxis;
btScalar jacDiagABInv = btScalar(1.) / m_jac[i].getDiagonal();
btScalar rel_vel;
rel_vel = normal.dot(vel);
//positional error (zeroth order error)
btScalar depth = -(pivotAInW - pivotBInW).dot(normal); //this is the error projected on the normal
btScalar impulse = depth*tau/timeStep * jacDiagABInv - rel_vel * jacDiagABInv;
m_appliedImpulse += impulse;
btVector3 impulse_vector = normal * impulse;
m_rbA.applyImpulse(impulse_vector, pivotAInW - m_rbA.getCenterOfMassPosition());
m_rbB.applyImpulse(-impulse_vector, pivotBInW - m_rbB.getCenterOfMassPosition());
}
}
{
///solve angular part
// get axes in world space
btVector3 axisA = getRigidBodyA().getCenterOfMassTransform().getBasis() * m_rbAFrame.getBasis().getColumn(2);
btVector3 axisB = getRigidBodyB().getCenterOfMassTransform().getBasis() * m_rbBFrame.getBasis().getColumn(2);
const btVector3& angVelA = getRigidBodyA().getAngularVelocity();
const btVector3& angVelB = getRigidBodyB().getAngularVelocity();
btVector3 angVelAroundHingeAxisA = axisA * axisA.dot(angVelA);
btVector3 angVelAroundHingeAxisB = axisB * axisB.dot(angVelB);
btVector3 angAorthog = angVelA - angVelAroundHingeAxisA;
btVector3 angBorthog = angVelB - angVelAroundHingeAxisB;
btVector3 velrelOrthog = angAorthog-angBorthog;
{
//solve orthogonal angular velocity correction
btScalar relaxation = btScalar(1.);
btScalar len = velrelOrthog.length();
if (len > btScalar(0.00001))
{
btVector3 normal = velrelOrthog.normalized();
btScalar denom = getRigidBodyA().computeAngularImpulseDenominator(normal) +
getRigidBodyB().computeAngularImpulseDenominator(normal);
// scale for mass and relaxation
velrelOrthog *= (btScalar(1.)/denom) * m_relaxationFactor;
}
//solve angular positional correction
btVector3 angularError = -axisA.cross(axisB) *(btScalar(1.)/timeStep);
btScalar len2 = angularError.length();
if (len2>btScalar(0.00001))
{
btVector3 normal2 = angularError.normalized();
btScalar denom2 = getRigidBodyA().computeAngularImpulseDenominator(normal2) +
getRigidBodyB().computeAngularImpulseDenominator(normal2);
angularError *= (btScalar(1.)/denom2) * relaxation;
}
m_rbA.applyTorqueImpulse(-velrelOrthog+angularError);
m_rbB.applyTorqueImpulse(velrelOrthog-angularError);
// solve limit
if (m_solveLimit)
{
btScalar amplitude = ( (angVelB - angVelA).dot( axisA )*m_relaxationFactor + m_correction* (btScalar(1.)/timeStep)*m_biasFactor ) * m_limitSign;
btScalar impulseMag = amplitude * m_kHinge;
// Clamp the accumulated impulse
btScalar temp = m_accLimitImpulse;
m_accLimitImpulse = btMax(m_accLimitImpulse + impulseMag, btScalar(0) );
impulseMag = m_accLimitImpulse - temp;
btVector3 impulse = axisA * impulseMag * m_limitSign;
m_rbA.applyTorqueImpulse(impulse);
m_rbB.applyTorqueImpulse(-impulse);
}
}
//apply motor
if (m_enableAngularMotor)
{
//todo: add limits too
btVector3 angularLimit(0,0,0);
btVector3 velrel = angVelAroundHingeAxisA - angVelAroundHingeAxisB;
btScalar projRelVel = velrel.dot(axisA);
btScalar desiredMotorVel = m_motorTargetVelocity;
btScalar motor_relvel = desiredMotorVel - projRelVel;
btScalar unclippedMotorImpulse = m_kHinge * motor_relvel;;
//todo: should clip against accumulated impulse
btScalar clippedMotorImpulse = unclippedMotorImpulse > m_maxMotorImpulse ? m_maxMotorImpulse : unclippedMotorImpulse;
clippedMotorImpulse = clippedMotorImpulse < -m_maxMotorImpulse ? -m_maxMotorImpulse : clippedMotorImpulse;
btVector3 motorImp = clippedMotorImpulse * axisA;
m_rbA.applyTorqueImpulse(motorImp+angularLimit);
m_rbB.applyTorqueImpulse(-motorImp-angularLimit);
}
}
}
void btHingeConstraint::solveConstraintObsolete(btSolverBody& bodyA,btSolverBody& bodyB,btScalar timeStep)
{
///for backwards compatibility during the transition to 'getInfo/getInfo2'
if (m_useSolveConstraintObsolete)
{
btVector3 pivotAInW = m_rbA.getCenterOfMassTransform()*m_rbAFrame.getOrigin();
btVector3 pivotBInW = m_rbB.getCenterOfMassTransform()*m_rbBFrame.getOrigin();
btScalar tau = btScalar(0.3);
//linear part
if (!m_angularOnly)
{
btVector3 rel_pos1 = pivotAInW - m_rbA.getCenterOfMassPosition();
btVector3 rel_pos2 = pivotBInW - m_rbB.getCenterOfMassPosition();
btVector3 vel1,vel2;
bodyA.getVelocityInLocalPointObsolete(rel_pos1,vel1);
bodyB.getVelocityInLocalPointObsolete(rel_pos2,vel2);
btVector3 vel = vel1 - vel2;
for (int i=0;i<3;i++)
{
const btVector3& normal = m_jac[i].m_linearJointAxis;
btScalar jacDiagABInv = btScalar(1.) / m_jac[i].getDiagonal();
btScalar rel_vel;
rel_vel = normal.dot(vel);
//positional error (zeroth order error)
btScalar depth = -(pivotAInW - pivotBInW).dot(normal); //this is the error projected on the normal
btScalar impulse = depth*tau/timeStep * jacDiagABInv - rel_vel * jacDiagABInv;
m_appliedImpulse += impulse;
btVector3 impulse_vector = normal * impulse;
btVector3 ftorqueAxis1 = rel_pos1.cross(normal);
btVector3 ftorqueAxis2 = rel_pos2.cross(normal);
bodyA.applyImpulse(normal*m_rbA.getInvMass(), m_rbA.getInvInertiaTensorWorld()*ftorqueAxis1,impulse);
bodyB.applyImpulse(normal*m_rbB.getInvMass(), m_rbB.getInvInertiaTensorWorld()*ftorqueAxis2,-impulse);
}
}
{
///solve angular part
// get axes in world space
btVector3 axisA = getRigidBodyA().getCenterOfMassTransform().getBasis() * m_rbAFrame.getBasis().getColumn(2);
btVector3 axisB = getRigidBodyB().getCenterOfMassTransform().getBasis() * m_rbBFrame.getBasis().getColumn(2);
btVector3 angVelA;
bodyA.getAngularVelocity(angVelA);
btVector3 angVelB;
bodyB.getAngularVelocity(angVelB);
btVector3 angVelAroundHingeAxisA = axisA * axisA.dot(angVelA);
btVector3 angVelAroundHingeAxisB = axisB * axisB.dot(angVelB);
btVector3 angAorthog = angVelA - angVelAroundHingeAxisA;
btVector3 angBorthog = angVelB - angVelAroundHingeAxisB;
btVector3 velrelOrthog = angAorthog-angBorthog;
{
//solve orthogonal angular velocity correction
btScalar len = velrelOrthog.length();
if (len > btScalar(0.00001))
{
btVector3 normal = velrelOrthog.normalized();
btScalar denom = getRigidBodyA().computeAngularImpulseDenominator(normal) +
getRigidBodyB().computeAngularImpulseDenominator(normal);
// scale for mass and relaxation
//velrelOrthog *= (btScalar(1.)/denom) * m_relaxationFactor;
bodyA.applyImpulse(btVector3(0,0,0), m_rbA.getInvInertiaTensorWorld()*velrelOrthog,-(btScalar(1.)/denom));
bodyB.applyImpulse(btVector3(0,0,0), m_rbB.getInvInertiaTensorWorld()*velrelOrthog,(btScalar(1.)/denom));
}
//solve angular positional correction
btVector3 angularError = axisA.cross(axisB) *(btScalar(1.)/timeStep);
btScalar len2 = angularError.length();
if (len2>btScalar(0.00001))
{
btVector3 normal2 = angularError.normalized();
btScalar denom2 = getRigidBodyA().computeAngularImpulseDenominator(normal2) +
getRigidBodyB().computeAngularImpulseDenominator(normal2);
//angularError *= (btScalar(1.)/denom2) * relaxation;
bodyA.applyImpulse(btVector3(0,0,0), m_rbA.getInvInertiaTensorWorld()*angularError,(btScalar(1.)/denom2));
bodyB.applyImpulse(btVector3(0,0,0), m_rbB.getInvInertiaTensorWorld()*angularError,-(btScalar(1.)/denom2));
}
// solve limit
if (m_solveLimit)
{
btScalar amplitude = ( (angVelB - angVelA).dot( axisA )*m_relaxationFactor + m_correction* (btScalar(1.)/timeStep)*m_biasFactor ) * m_limitSign;
btScalar impulseMag = amplitude * m_kHinge;
// Clamp the accumulated impulse
btScalar temp = m_accLimitImpulse;
m_accLimitImpulse = btMax(m_accLimitImpulse + impulseMag, btScalar(0) );
impulseMag = m_accLimitImpulse - temp;
bodyA.applyImpulse(btVector3(0,0,0), m_rbA.getInvInertiaTensorWorld()*axisA,impulseMag * m_limitSign);
bodyB.applyImpulse(btVector3(0,0,0), m_rbB.getInvInertiaTensorWorld()*axisA,-(impulseMag * m_limitSign));
}
}
//apply motor
if (m_enableAngularMotor)
{
//todo: add limits too
btVector3 angularLimit(0,0,0);
btVector3 velrel = angVelAroundHingeAxisA - angVelAroundHingeAxisB;
btScalar projRelVel = velrel.dot(axisA);
btScalar desiredMotorVel = m_motorTargetVelocity;
btScalar motor_relvel = desiredMotorVel - projRelVel;
btScalar unclippedMotorImpulse = m_kHinge * motor_relvel;;
// accumulated impulse clipping:
btScalar fMaxImpulse = m_maxMotorImpulse;
btScalar newAccImpulse = m_accMotorImpulse + unclippedMotorImpulse;
btScalar clippedMotorImpulse = unclippedMotorImpulse;
if (newAccImpulse > fMaxImpulse)
{
newAccImpulse = fMaxImpulse;
clippedMotorImpulse = newAccImpulse - m_accMotorImpulse;
}
else if (newAccImpulse < -fMaxImpulse)
{
newAccImpulse = -fMaxImpulse;
clippedMotorImpulse = newAccImpulse - m_accMotorImpulse;
}
m_accMotorImpulse += clippedMotorImpulse;
bodyA.applyImpulse(btVector3(0,0,0), m_rbA.getInvInertiaTensorWorld()*axisA,clippedMotorImpulse);
bodyB.applyImpulse(btVector3(0,0,0), m_rbB.getInvInertiaTensorWorld()*axisA,-clippedMotorImpulse);
}
}
}
}
void HingeJointSW::solve(float p_step) {
Vector3 pivotAInW = A->get_transform().xform(m_rbAFrame.origin);
Vector3 pivotBInW = B->get_transform().xform(m_rbBFrame.origin);
//real_t tau = real_t(0.3);
//linear part
if (!m_angularOnly) {
Vector3 rel_pos1 = pivotAInW - A->get_transform().origin;
Vector3 rel_pos2 = pivotBInW - B->get_transform().origin;
Vector3 vel1 = A->get_velocity_in_local_point(rel_pos1);
Vector3 vel2 = B->get_velocity_in_local_point(rel_pos2);
Vector3 vel = vel1 - vel2;
for (int i = 0; i < 3; i++) {
const Vector3 &normal = m_jac[i].m_linearJointAxis;
real_t jacDiagABInv = real_t(1.) / m_jac[i].getDiagonal();
real_t rel_vel;
rel_vel = normal.dot(vel);
//positional error (zeroth order error)
real_t depth = -(pivotAInW - pivotBInW).dot(normal); //this is the error projected on the normal
real_t impulse = depth * tau / p_step * jacDiagABInv - rel_vel * jacDiagABInv;
m_appliedImpulse += impulse;
Vector3 impulse_vector = normal * impulse;
A->apply_impulse(pivotAInW - A->get_transform().origin, impulse_vector);
B->apply_impulse(pivotBInW - B->get_transform().origin, -impulse_vector);
}
}
{
///solve angular part
// get axes in world space
Vector3 axisA = A->get_transform().basis.xform(m_rbAFrame.basis.get_axis(2));
Vector3 axisB = B->get_transform().basis.xform(m_rbBFrame.basis.get_axis(2));
const Vector3 &angVelA = A->get_angular_velocity();
const Vector3 &angVelB = B->get_angular_velocity();
Vector3 angVelAroundHingeAxisA = axisA * axisA.dot(angVelA);
Vector3 angVelAroundHingeAxisB = axisB * axisB.dot(angVelB);
Vector3 angAorthog = angVelA - angVelAroundHingeAxisA;
Vector3 angBorthog = angVelB - angVelAroundHingeAxisB;
Vector3 velrelOrthog = angAorthog - angBorthog;
{
//solve orthogonal angular velocity correction
real_t relaxation = real_t(1.);
real_t len = velrelOrthog.length();
if (len > real_t(0.00001)) {
Vector3 normal = velrelOrthog.normalized();
real_t denom = A->compute_angular_impulse_denominator(normal) +
B->compute_angular_impulse_denominator(normal);
// scale for mass and relaxation
velrelOrthog *= (real_t(1.) / denom) * m_relaxationFactor;
}
//solve angular positional correction
Vector3 angularError = -axisA.cross(axisB) * (real_t(1.) / p_step);
real_t len2 = angularError.length();
if (len2 > real_t(0.00001)) {
Vector3 normal2 = angularError.normalized();
real_t denom2 = A->compute_angular_impulse_denominator(normal2) +
B->compute_angular_impulse_denominator(normal2);
angularError *= (real_t(1.) / denom2) * relaxation;
}
A->apply_torque_impulse(-velrelOrthog + angularError);
B->apply_torque_impulse(velrelOrthog - angularError);
// solve limit
if (m_solveLimit) {
real_t amplitude = ((angVelB - angVelA).dot(axisA) * m_relaxationFactor + m_correction * (real_t(1.) / p_step) * m_biasFactor) * m_limitSign;
real_t impulseMag = amplitude * m_kHinge;
// Clamp the accumulated impulse
real_t temp = m_accLimitImpulse;
m_accLimitImpulse = MAX(m_accLimitImpulse + impulseMag, real_t(0));
impulseMag = m_accLimitImpulse - temp;
Vector3 impulse = axisA * impulseMag * m_limitSign;
A->apply_torque_impulse(impulse);
B->apply_torque_impulse(-impulse);
}
}
//apply motor
if (m_enableAngularMotor) {
//todo: add limits too
Vector3 angularLimit(0, 0, 0);
Vector3 velrel = angVelAroundHingeAxisA - angVelAroundHingeAxisB;
real_t projRelVel = velrel.dot(axisA);
real_t desiredMotorVel = m_motorTargetVelocity;
real_t motor_relvel = desiredMotorVel - projRelVel;
real_t unclippedMotorImpulse = m_kHinge * motor_relvel;
//todo: should clip against accumulated impulse
real_t clippedMotorImpulse = unclippedMotorImpulse > m_maxMotorImpulse ? m_maxMotorImpulse : unclippedMotorImpulse;
clippedMotorImpulse = clippedMotorImpulse < -m_maxMotorImpulse ? -m_maxMotorImpulse : clippedMotorImpulse;
Vector3 motorImp = clippedMotorImpulse * axisA;
A->apply_torque_impulse(motorImp + angularLimit);
B->apply_torque_impulse(-motorImp - angularLimit);
}
}
}