Jordan wrote:
> 
> I have some questions about polygons (when used in meshes in
> particular) that are probably going to seem sorta dumb.  First of all,
> are they limited to 3 or 4 edges, and if so, why?

No.  However, many of the cool things done with polygons in a mesh,
such as surface subidvision, work best with triangles or quadrilaterals.

For instance, the Loop surface requires triangles and generates
triangles, while the Catmull-Clark surface can take any shape polygon,
but generates four-siders.

An important caveat:  The mesh object used by POV-Ray uses only
triangles (although this may change in the future).  Fortunately,
other polygons are rather easily divisible into triangles.

> Secondly, does every edge of every polygon in a mesh have to be shared
> by one (and only one) neighboring polygon?  For example,
> 
>  -----------
> |     |     |
> | 1   | 2   |
> |_____|     |
> |     |     |
> | 3   |     |
> |_____|_____|
> 
> would be wrong, but,
> 
>  -----------
> |     |     |
> | 1   | 2   |
> |_____|_____|
> |     |     |
> | 4   | 3   |
> |_____|_____|
> 
> would be fine.  If so, why?

Not the case.  In POV-Ray the mesh would be comprised of triangles,
and you could butt two triangles against the edge of a third, but
keeping the results seamless would be difficult.

If for some reason you are unwilling to divide your quadrilaterals,
pentagons, etc., into triangles, then in POV-Ray you will have to use a
union of polygons instead of a mesh.  By doing so you will miss out on
a great number of advantages that the mesh object has, but sometimes
it can't be avoided.

As for the behaviors of other renderers, I can't say.

> These questions have really been nagging at me
> lately, so any enlightenment you guys can provide would be very
> appreciated.  Thanks in advance.

Glad to be of service.

Regards,
John
-- 
ICQ: 46085459

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