On 3 Sep 1999 17:29:39 -0400, par### [at] fwicom (Ron Parker) wrote:

>On Fri, 03 Sep 1999 21:20:21 GMT, Cliff Bowman wrote:
>>And I'd just been working from conjecture... if such double faces WERE
>>imported into POV, how would it cope I wonder? I'll have to give it a
>>try. I can't help but think that with 2 triangles at the same point
>>POv would have difficulty deciding on which one to render at any given
>>X-Y co-ordinate - sometimes picking the one with the "correct" normal
>>and sometimes picking the other...
>
>It'd probably still work.  POV tends to flip the normal to the "correct"
>orientation anyway, so both triangles would be essentially identical and
>it wouldn't matter which of the two you hit.

I've seen some pretty ugly, gappy .OBJ files imported with other tools
(OBJ2POV IIRC) where the triangles didn't get flipped - which is one
reason I've found announcements like SSS interesting. Figuring a way
to calculate normals for point son a mesh and comparing them to the
original to see if it's pointing the wrong way is something I'd like
to try (later). I'd rather not just recalculate normals in case there
are .OBJ files which actually *use* the normals they supply (for
bumps, dents, etc.).

I've got a good example of an OBJ file with many correct and many
incorrect normals. 3D Win seeems to do a good job of correcting those
facets when it exports to POV, but sadly not when it exports back to
OBJ format (no idea why).

I did try using the OpenGL version of 3D Win to see what it was
holding internally after importing an OBJ, but I can't get it not to
crash my PC :(

So - examining SSS and learning how to calculate normals seems like a
way to go :)


Cheers,

Cliff Bowman
Why not pay my 3D Dr Who site a visit at http://www.who3d.cwc.net/

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