// create constraint
void MBulletContext::createConstraint(unsigned int * constraintId, unsigned int parentObjectId, unsigned int objectId, const MVector3 & pivot, bool disableParentCollision)
{
btRigidBody * bA = btRigidBody::upcast(m_collisionObjects[parentObjectId]);
btRigidBody * bB = btRigidBody::upcast(m_collisionObjects[objectId]);
if(bA && bB)
{
bA->setActivationState(DISABLE_DEACTIVATION);
bB->setActivationState(DISABLE_DEACTIVATION);
*constraintId = m_constraints.size();
MVector3 position, euler;
MQuaternion rotation;
MMatrix4x4 matrix, matrix1, matrix2, rotMatrix;
rotMatrix.setRotationEuler(90, 0, 0);
getObjectTransform(parentObjectId, &position, &rotation);
matrix1.setRotationAxis(rotation.getAngle(), rotation.getAxis());
matrix1.setTranslationPart(position);
getObjectTransform(objectId, &position, &rotation);
matrix2.setRotationAxis(rotation.getAngle(), rotation.getAxis());
matrix2.setTranslationPart(position + matrix2.getRotatedVector3(pivot));
matrix = (matrix1.getInverse() * matrix2) * rotMatrix;
euler = matrix.getEulerAngles();
position = matrix.getTranslationPart();
rotation.setFromAngles(euler.x, euler.y, euler.z);
btTransform frameInA, frameInB;
frameInA = btTransform::getIdentity();
frameInA.setOrigin(btVector3(position.x, position.y, position.z));
frameInA.setRotation(btQuaternion(rotation.values[0], rotation.values[1], rotation.values[2], rotation.values[3]));
rotation.setFromAngles(90, 0, 0);
frameInB = btTransform::getIdentity();
frameInB.setOrigin(btVector3(pivot.x, pivot.y, pivot.z));
frameInB.setRotation(btQuaternion(rotation.values[0], rotation.values[1], rotation.values[2], rotation.values[3]));
btGeneric6DofSpringConstraint * constraint = new btGeneric6DofSpringConstraint(
*bA, *bB, frameInA, frameInB, true
);
m_constraints.push_back(constraint);
m_dynamicsWorld->addConstraint(constraint, disableParentCollision);
}
}
