//bilateral constraint between two dynamic objects
void resolveSingleBilateral(btRigidBody& body1, const btVector3& pos1,
btRigidBody& body2, const btVector3& pos2,
btScalar distance, const btVector3& normal,btScalar& impulse ,btScalar timeStep)
{
(void)timeStep;
(void)distance;
btScalar normalLenSqr = normal.length2();
btAssert(btFabs(normalLenSqr) < btScalar(1.1));
if (normalLenSqr > btScalar(1.1))
{
impulse = btScalar(0.);
return;
}
btVector3 rel_pos1 = pos1 - body1.getCenterOfMassPosition();
btVector3 rel_pos2 = pos2 - body2.getCenterOfMassPosition();
//this jacobian entry could be re-used for all iterations
btVector3 vel1 = body1.getVelocityInLocalPoint(rel_pos1);
btVector3 vel2 = body2.getVelocityInLocalPoint(rel_pos2);
btVector3 vel = vel1 - vel2;
btJacobianEntry jac(body1.getCenterOfMassTransform().getBasis().transpose(),
body2.getCenterOfMassTransform().getBasis().transpose(),
rel_pos1,rel_pos2,normal,body1.getInvInertiaDiagLocal(),body1.getInvMass(),
body2.getInvInertiaDiagLocal(),body2.getInvMass());
btScalar jacDiagAB = jac.getDiagonal();
btScalar jacDiagABInv = btScalar(1.) / jacDiagAB;
btScalar rel_vel = jac.getRelativeVelocity(
body1.getLinearVelocity(),
body1.getCenterOfMassTransform().getBasis().transpose() * body1.getAngularVelocity(),
body2.getLinearVelocity(),
body2.getCenterOfMassTransform().getBasis().transpose() * body2.getAngularVelocity());
btScalar a;
a=jacDiagABInv;
rel_vel = normal.dot(vel);
//todo: move this into proper structure
btScalar contactDamping = btScalar(0.2);
#ifdef ONLY_USE_LINEAR_MASS
btScalar massTerm = btScalar(1.) / (body1.getInvMass() + body2.getInvMass());
impulse = - contactDamping * rel_vel * massTerm;
#else
btScalar velocityImpulse = -contactDamping * rel_vel * jacDiagABInv;
impulse = velocityImpulse;
#endif
}
void btWheelInfo::updateWheel(const btRigidBody& chassis,RaycastInfo& raycastInfo)
{
(void)raycastInfo;
if (m_raycastInfo.m_isInContact)
{
btScalar project= m_raycastInfo.m_contactNormalWS.dot( m_raycastInfo.m_wheelDirectionWS );
btVector3 chassis_velocity_at_contactPoint;
btVector3 relpos = m_raycastInfo.m_contactPointWS - chassis.getCenterOfMassPosition();
chassis_velocity_at_contactPoint = chassis.getVelocityInLocalPoint( relpos );
btScalar projVel = m_raycastInfo.m_contactNormalWS.dot( chassis_velocity_at_contactPoint );
if ( project >= btScalar(-0.1))
{
m_suspensionRelativeVelocity = btScalar(0.0);
m_clippedInvContactDotSuspension = btScalar(1.0) / btScalar(0.1);
}
else
{
btScalar inv = btScalar(-1.) / project;
m_suspensionRelativeVelocity = projVel * inv;
m_clippedInvContactDotSuspension = inv;
}
}
else // Not in contact : position wheel in a nice (rest length) position
{
m_raycastInfo.m_suspensionLength = this->getSuspensionRestLength();
m_suspensionRelativeVelocity = btScalar(0.0);
m_raycastInfo.m_contactNormalWS = -m_raycastInfo.m_wheelDirectionWS;
m_clippedInvContactDotSuspension = btScalar(1.0);
}
}
btScalar btTranslationalLimitMotor::solveLinearAxis(
btScalar timeStep,
btScalar jacDiagABInv,
btRigidBody& body1,const btVector3 &pointInA,
btRigidBody& body2,const btVector3 &pointInB,
int limit_index,
const btVector3 & axis_normal_on_a,
const btVector3 & anchorPos)
{
///find relative velocity
// btVector3 rel_pos1 = pointInA - body1.getCenterOfMassPosition();
// btVector3 rel_pos2 = pointInB - body2.getCenterOfMassPosition();
btVector3 rel_pos1 = anchorPos - body1.getCenterOfMassPosition();
btVector3 rel_pos2 = anchorPos - body2.getCenterOfMassPosition();
btVector3 vel1 = body1.getVelocityInLocalPoint(rel_pos1);
btVector3 vel2 = body2.getVelocityInLocalPoint(rel_pos2);
btVector3 vel = vel1 - vel2;
btScalar rel_vel = axis_normal_on_a.dot(vel);
/// apply displacement correction
//positional error (zeroth order error)
btScalar depth = -(pointInA - pointInB).dot(axis_normal_on_a);
btScalar lo = btScalar(-BT_LARGE_FLOAT);
btScalar hi = btScalar(BT_LARGE_FLOAT);
btScalar minLimit = m_lowerLimit[limit_index];
btScalar maxLimit = m_upperLimit[limit_index];
//handle the limits
if (minLimit < maxLimit)
{
{
if (depth > maxLimit)
{
depth -= maxLimit;
lo = btScalar(0.);
}
else
{
if (depth < minLimit)
{
depth -= minLimit;
hi = btScalar(0.);
}
else
{
return 0.0f;
}
}
}
}
btScalar normalImpulse= m_limitSoftness*(m_restitution*depth/timeStep - m_damping*rel_vel) * jacDiagABInv;
btScalar oldNormalImpulse = m_accumulatedImpulse[limit_index];
btScalar sum = oldNormalImpulse + normalImpulse;
m_accumulatedImpulse[limit_index] = sum > hi ? btScalar(0.) : sum < lo ? btScalar(0.) : sum;
normalImpulse = m_accumulatedImpulse[limit_index] - oldNormalImpulse;
btVector3 impulse_vector = axis_normal_on_a * normalImpulse;
body1.applyImpulse( impulse_vector, rel_pos1);
body2.applyImpulse(-impulse_vector, rel_pos2);
return normalImpulse;
}
void btSliderConstraint::solveConstraintInt(btRigidBody& rbA, btRigidBody& rbB)
{
int i;
// linear
btVector3 velA = rbA.getVelocityInLocalPoint(m_relPosA);
btVector3 velB = rbB.getVelocityInLocalPoint(m_relPosB);
btVector3 vel = velA - velB;
for(i = 0; i < 3; i++)
{
const btVector3& normal = m_jacLin[i].m_linearJointAxis;
btScalar rel_vel = normal.dot(vel);
// calculate positional error
btScalar depth = m_depth[i];
// get parameters
btScalar softness = (i) ? m_softnessOrthoLin : (m_solveLinLim ? m_softnessLimLin : m_softnessDirLin);
btScalar restitution = (i) ? m_restitutionOrthoLin : (m_solveLinLim ? m_restitutionLimLin : m_restitutionDirLin);
btScalar damping = (i) ? m_dampingOrthoLin : (m_solveLinLim ? m_dampingLimLin : m_dampingDirLin);
// calcutate and apply impulse
btScalar normalImpulse = softness * (restitution * depth / m_timeStep - damping * rel_vel) * m_jacLinDiagABInv[i];
btVector3 impulse_vector = normal * normalImpulse;
rbA.applyImpulse( impulse_vector, m_relPosA);
rbB.applyImpulse(-impulse_vector, m_relPosB);
if(m_poweredLinMotor && (!i))
{ // apply linear motor
if(m_accumulatedLinMotorImpulse < m_maxLinMotorForce)
{
btScalar desiredMotorVel = m_targetLinMotorVelocity;
btScalar motor_relvel = desiredMotorVel + rel_vel;
normalImpulse = -motor_relvel * m_jacLinDiagABInv[i];
// clamp accumulated impulse
btScalar new_acc = m_accumulatedLinMotorImpulse + btFabs(normalImpulse);
if(new_acc > m_maxLinMotorForce)
{
new_acc = m_maxLinMotorForce;
}
btScalar del = new_acc - m_accumulatedLinMotorImpulse;
if(normalImpulse < btScalar(0.0))
{
normalImpulse = -del;
}
else
{
normalImpulse = del;
}
m_accumulatedLinMotorImpulse = new_acc;
// apply clamped impulse
impulse_vector = normal * normalImpulse;
rbA.applyImpulse( impulse_vector, m_relPosA);
rbB.applyImpulse(-impulse_vector, m_relPosB);
}
}
}
// angular
// get axes in world space
btVector3 axisA = m_calculatedTransformA.getBasis().getColumn(0);
btVector3 axisB = m_calculatedTransformB.getBasis().getColumn(0);
const btVector3& angVelA = rbA.getAngularVelocity();
const btVector3& angVelB = rbB.getAngularVelocity();
btVector3 angVelAroundAxisA = axisA * axisA.dot(angVelA);
btVector3 angVelAroundAxisB = axisB * axisB.dot(angVelB);
btVector3 angAorthog = angVelA - angVelAroundAxisA;
btVector3 angBorthog = angVelB - angVelAroundAxisB;
btVector3 velrelOrthog = angAorthog-angBorthog;
//solve orthogonal angular velocity correction
btScalar len = velrelOrthog.length();
if (len > btScalar(0.00001))
{
btVector3 normal = velrelOrthog.normalized();
btScalar denom = rbA.computeAngularImpulseDenominator(normal) + rbB.computeAngularImpulseDenominator(normal);
velrelOrthog *= (btScalar(1.)/denom) * m_dampingOrthoAng * m_softnessOrthoAng;
}
//solve angular positional correction
btVector3 angularError = axisA.cross(axisB) *(btScalar(1.)/m_timeStep);
btScalar len2 = angularError.length();
if (len2>btScalar(0.00001))
{
btVector3 normal2 = angularError.normalized();
btScalar denom2 = rbA.computeAngularImpulseDenominator(normal2) + rbB.computeAngularImpulseDenominator(normal2);
angularError *= (btScalar(1.)/denom2) * m_restitutionOrthoAng * m_softnessOrthoAng;
}
// apply impulse
rbA.applyTorqueImpulse(-velrelOrthog+angularError);
rbB.applyTorqueImpulse(velrelOrthog-angularError);
btScalar impulseMag;
//solve angular limits
if(m_solveAngLim)
{
impulseMag = (angVelB - angVelA).dot(axisA) * m_dampingLimAng + m_angDepth * m_restitutionLimAng / m_timeStep;
impulseMag *= m_kAngle * m_softnessLimAng;
}
else
{
impulseMag = (angVelB - angVelA).dot(axisA) * m_dampingDirAng + m_angDepth * m_restitutionDirAng / m_timeStep;
impulseMag *= m_kAngle * m_softnessDirAng;
}
btVector3 impulse = axisA * impulseMag;
rbA.applyTorqueImpulse(impulse);
rbB.applyTorqueImpulse(-impulse);
//apply angular motor
if(m_poweredAngMotor)
{
if(m_accumulatedAngMotorImpulse < m_maxAngMotorForce)
{
btVector3 velrel = angVelAroundAxisA - angVelAroundAxisB;
btScalar projRelVel = velrel.dot(axisA);
btScalar desiredMotorVel = m_targetAngMotorVelocity;
btScalar motor_relvel = desiredMotorVel - projRelVel;
btScalar angImpulse = m_kAngle * motor_relvel;
// clamp accumulated impulse
btScalar new_acc = m_accumulatedAngMotorImpulse + btFabs(angImpulse);
if(new_acc > m_maxAngMotorForce)
{
new_acc = m_maxAngMotorForce;
}
btScalar del = new_acc - m_accumulatedAngMotorImpulse;
if(angImpulse < btScalar(0.0))
{
angImpulse = -del;
}
else
{
angImpulse = del;
}
m_accumulatedAngMotorImpulse = new_acc;
// apply clamped impulse
btVector3 motorImp = angImpulse * axisA;
m_rbA.applyTorqueImpulse(motorImp);
m_rbB.applyTorqueImpulse(-motorImp);
}
}
} // btSliderConstraint::solveConstraint()
