View Full Version : "vt" OBJ and "st" RIB

06 June 2005, 09:28 AM
Hello everybody,

Since there is not yet output for UV 's (obj or rib) in Silo, I have a crucial question concerning UV maps. First of all, I do little basic programation of a generator for my own purpose. At this stage it is an application that generates simple (and/or complex) 3d shapes and its output is a RIB file ready for rendering Art Imagery. And I want to include uv mapping (textures) in my program.

My request is: :hmm:
How to convert OBJ "vt" data in an identical RIB "st" data that is readable by renderman (3Delight), I didn't find any documentation on writing "st" data to map images to the models I want?

Is there anyone who can help me to find a link, a tutorial or a book that discribes the process of writing this particular stuff. Or if it already exist some converter that can do this.

Any suggestion ?
Thank you so much.


PS: same topic is actually posted on the Silo forum

06 June 2005, 05:41 PM
I assume that you have the spec for OBJ. OBJ mostly uses a vertex-face method of assigning UVs, allowing discontinuous UV mappings.

In RIB, you'll want to use face-varying st coordinates. The spec is here:

Advanced Renderman is a good book for explaining some of these issues.
Another idea is to use a package that supports UV mapping and rib output, and learn by example - the spec will probably make more sense that way.

06 June 2005, 05:53 AM
Hi nurcc,

In RIB, you'll want to use face-varying st coordinates
That's it ... "facevarying float st[2]" is right, I recieved yesterday a fast and complete response from 3Delight. Sorry but I'm not already enough familiar with Renderman, so my learning curve continues.

Another idea is to use a package that supports UV mapping and rib output
For UV and rib output the only packages I checked are only plugins of applications that I don't own or are'nt running on OSX. So I'll try to do it myself for now because the generator, I'm working on, must control the texture placement of the generated shapes.
Anyways thank you for the input,


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06 June 2005, 05:53 AM
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