private static double TransformToAxis(CollisionBox box, Vector3d axis)
{
return
(box.HalfSize.x * Vector3d.AbsDot(axis, box.GetAxis(0)) +
box.HalfSize.y * Vector3d.AbsDot(axis, box.GetAxis(1)) +
box.HalfSize.z * Vector3d.AbsDot(axis, box.GetAxis(2)));
}
/// <summary>
/// This function checks if the two boxes overlap
/// along the given axis.The final parameter toCentre
/// is used to pass in the vector between the boxes centre
/// points, to avoid having to recalculate it each time.
/// </summary>
private static bool OverlapOnAxis(CollisionBox one, CollisionBox two, Vector3d axis, Vector3d toCentre)
{
// Project the half-size of one onto axis
double oneProject = TransformToAxis(one, axis);
double twoProject = TransformToAxis(two, axis);
// Project this onto the axis
double distance = Vector3d.AbsDot(toCentre, axis);
// Check for overlap
return(distance < oneProject + twoProject);
}
/// <summary>
/// This function checks if the two boxes overlap
/// along the given axis, returning the ammount of overlap.
/// The final parameter toCentre
/// is used to pass in the vector between the boxes centre
/// points, to avoid having to recalculate it each time.
/// </summary>
private static double PenetrationOnAxis(CollisionBox one, CollisionBox two, Vector3d axis, Vector3d toCentre)
{
// Project the half-size of one onto axis
double oneProject = TransformToAxis(one, axis);
double twoProject = TransformToAxis(two, axis);
// Project this onto the axis
double distance = Vector3d.AbsDot(toCentre, axis);
// Return the overlap (i.e. positive indicates
// overlap, negative indicates separation).
return(oneProject + twoProject - distance);
}
