[Radiance-general] Re: obj2rad failing

[Greg Ward]

Hi Erwin,

The problem with that face is that it refers to vertex normals 29760,  
29761, and 29763, whereas you've only defined 544 normals up until  
that point in the file.  It is illegal to refer to an undefined index  
in obj2rad, hence the reported error.  None of the other OBJ file  
converters will like it, either.  The faces up until that point in  
the file don't use vertex normals, so they pass without complaint.

-Greg

P.S.  To those of you confused by this exchange, Erwin sent me his  
OBJ file in a separate e-mail at my request.

> From: "Erwin Zierler" <radiance at rendigo.com>
> Date: October 7, 2008 3:19:01 PM PDT
>
> Hi all,
>
> I am currently testing differrent converters with what you could  
> call 'real-world' scene files originating from differrent CAD  
> systems and modellers. While exploring the capabilities of obj2rad  
> I noticed that it fails on a OBJ File (exported from ArchiCAD) with  
> the following error:
>
> example.obj: Wavefront syntax error near line 167037: Bad face
>
> Here is the 'bad' part of the file (line 167037 - 167041)
>
> f  29760/83929/29760 29761/83930/29761 29762/83931/29762  
> 29763/83932/29763
> vt 42.5353 8.46865
> vt 42.5353 8.474
> vt 42.53 8.474
> vt 42.53 8.469
>
> Other parts of the obj file work fine:
>
> f  29682/83789 29683/83790 29684/83791 29685/83792
> vt -0.019984 -0.400179
> vt 8.56333 -0.400179
> vt 8.58332 0
> vt 0 0
>
> The OBJ file format specification tells me that both 'f' lines are  
> perfectly legal:
>
> Using v, vt, and vn to represent geometric vertices, texture vertices,
> and vertex normals, the statement would read:
>
>     f v/vt/vn v/vt/vn v/vt/vn v/vt/vn
>
> But obj2rad doesn't seem to like the 3rd number(s) vn which are  
> supposed to represent the vertex normals. The obj2rad man page  
> doesn't go into much detail about the 'f' statement with respect to  
> allowed format. Running obj2rad -f (ignoring vertex normal  
> information) also fails on the exact same line.
>
> I will try to get ahold of some smaller ArchiCAD OBJ exports now  
> and see if I can narrow down the problem. If anyone has some ideas  
> or similar experiences I would sure appreciate to hear from you!
> TIA,
>  Erwin