Compute a set of box properties at normalised $(x,y,z)$ parameters. To wit, the local plane, the nearest corner and the nearest edge.

Input parameters:

1. Bx → Box to evaluate.
2. Xt → Normalised parameter in the box X direction.
3. Yt → Normalised parameter in the box Y direction.
4. Zt → Normalised parameter in the box Z direction.

Output parameters:

1. Pl → Plane aligned with box orientation at the given parameters.
2. Cc → Box corner closest to the point at the given parameters.
3. Ce → Box edge closest to the point at the given parameters.