void CylindricalBirefringentMaterial::rotationAxis( arma::vec &axis)
{
// If there is some kind of cylindrical symmetry, two of the principal
// inertia should be equal.
double I12 = principalInertia(0)-principalInertia(1);
double I13 = principalInertia(0)-principalInertia(2);
double I23 = principalInertia(1)-principalInertia(2);
if (( abs(I12) < abs(I13) ) && ( abs(I12) < abs(I23) ))
{
// 1 and 2 is most similar
axis = principalAxes.col(2);
princAxis = 2;
}
else if (( abs(I13) < abs(I12) ) && ( abs(I13) < abs(I23) ))
{
// 1 and 3 is most similar
axis = principalAxes.col(1);
princAxis = 1;
}
else
{
// 2 and 3 is most similar
axis = principalAxes.col(0);
princAxis = 0;
}
}
bool csBulletRigidBody::AddBulletObject ()
{
// TODO: don't recompute everything if the internal scale hasn't changed
if (insideWorld)
RemoveBulletObject ();
btVector3 localInertia (0.0f, 0.0f, 0.0f);
float mass = GetMass ();
btCollisionShape* shape;
btTransform principalAxis;
principalAxis.setIdentity ();
btVector3 principalInertia(0,0,0);
//Create btRigidBody
if (compoundShape)
{
int shapeCount = compoundShape->getNumChildShapes ();
CS_ALLOC_STACK_ARRAY(btScalar, masses, shapeCount);
for (int i = 0; i < shapeCount; i++)
masses[i] = density * colliders[i]->GetVolume ();
if (shapeChanged)
{
compoundShape->calculatePrincipalAxisTransform
(masses, principalAxis, principalInertia);
// apply principal axis
// creation is faster using a new compound to store the shifted children
btCompoundShape* newCompoundShape = new btCompoundShape();
for (int i = 0; i < shapeCount; i++)
{
btTransform newChildTransform =
principalAxis.inverse() * compoundShape->getChildTransform (i);
newCompoundShape->addChildShape(newChildTransform,
compoundShape->getChildShape (i));
shapeChanged = false;
}
delete compoundShape;
compoundShape = newCompoundShape;
}
shape = compoundShape;
}
else
{
shape = colliders[0]->shape;
principalAxis = CSToBullet (relaTransforms[0], system->getInternalScale ());
}
// create new motion state
btTransform trans;
motionState->getWorldTransform (trans);
trans = trans * motionState->inversePrincipalAxis;
delete motionState;
motionState = new csBulletMotionState (this, trans * principalAxis,
principalAxis);
//shape->calculateLocalInertia (mass, localInertia);
btRigidBody::btRigidBodyConstructionInfo infos (mass, motionState,
shape, localInertia);
infos.m_friction = friction;
infos.m_restitution = elasticity;
infos.m_linearDamping = linearDampening;
infos.m_angularDamping = angularDampening;
// create new rigid body
btBody = new btRigidBody (infos);
btObject = btBody;
if (haveStaticColliders > 0)
physicalState = CS::Physics::STATE_STATIC;
SetState (physicalState);
sector->bulletWorld->addRigidBody (btBody, collGroup.value, collGroup.mask);
btBody->setUserPointer (dynamic_cast<CS::Collisions::iCollisionObject*> (
dynamic_cast<csBulletCollisionObject*>(this)));
insideWorld = true;
return true;
}
