Given a plane and a 3D point, transform the 3D point to a 2D coordinate along the plane.

This is harder than it sounds. This is to determine UV coords for any point in space, relative to any plane. The d# part of the equation is irrelevant, because the 3D point's distance from the plane doesn't matter, just it's 2D coordinates relative to that plane.

TextureCoord(x#,y#,z#,nx#,ny#,nz#)
Returns u# and v# values
End Function