Add images for cylindrical and spherical mapping

[Travis Cobbs]

I propose that we add the images from the post below to the cylindrical and spherical mapping portions of the TEXMAP spec:

https://forums.ldraw.org/thread-4261-pos...ml#pid6818

[Roland Melkert]

I propose that we add the images from the post below to the cylindrical and spherical mapping portions of the TEXMAP spec:

https://forums.ldraw.org/thread-4261-pos...ml#pid6818

Don't see why not.

Maybe add the texture coordinates to the surfaces?

As those can be confusing, especially for the cylindrical one. As p3 is used to indicate the bottom while that should become 1.0 in texture space. The planer one uses the top which becomes 0.0 in texture space.

In LDCad 1.6b I've adjusted things so the position of 'p3' doesn't matter anymore which might make things easier for part authors. P3 is then only used to calculate the radius and center of the texture by calculating the perpendicular vector to p1-p2. Vertical texture coordinates are then normalized distances to the top plane.