View Full Version : 3-sided patches

12 December 2003, 05:53 PM
Does anyone know the formulas/algorithm/math to make these work? I understand 4-sided patches, but the damned book doesn't say anything about 3-sided patches....

Help :(

12 December 2003, 06:00 PM
Oh to be more specific I'm looking into Bezier patches.
Thanks :)

12 December 2003, 08:36 AM
Check out ATI's developers section for information on N-Patches. Essentially what they do is to convert each triangle in a mesh into a bezier triangle, and then tesselate that. IIRC there are a couple of pdfs on their site that outline how to (a) get bezier control points from just a triangle's vertices+normals, and (b) how to render bezier triangles.

Look for the paper "Curved PN Triangles" on this ( page (links to


Ash Henstock
12 December 2003, 10:34 AM
There's an N-patches article ( on gamasutra. You'll need to register at gamasutra if you havn't already.

12 December 2003, 02:50 PM
Thanks a lot! :):)
These'll take some digesting :p

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