On Wed, 01 Sep 1999 06:11:34 GMT, NOS### [at] ibmnet (Thomas
Baier) wrote:

[snip]
>I have found and tested some very strange OBJ files with missing
>vertices, wrong face to vertex links, double faces and lots of
>degenerated faces.
>
>3DWin tries to fix this errors and throws out such faces.
>
OBJ files do seem to be annoyingly... poorly written, don't they?
Degenerate faces is the first problem that surprised me (closely
followed by faces with 26 verteces - which I think I've now sussed).
the number of degenerate faces the average .OBJ contains is almost
depressing.

Double faces I think I know the reason for. A lot of modellers seem to
get the normals *wrong* and so users sometimes make a copy of the
model, flip the normals, and combine the two sets of meshes.

Dirty, and probably works in many cases (i.e. patches holes) but time
and memory are both wasted. I can't help but feel it'd cause some
renderers to cough and splutter too  - though as I've not knowingly
come across this yet I don't know how much POV "likes" or dislikes it.

I'd expect there to be "coincident faces" (is that the term?) problems
though.


Cheers,

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

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