I tried googling and searching on stack but I didn\'t find anything :-(
( Mapping irregular shapes or other polygons (cartoons, sprites) to triangles in OpenGL ES )
In non-ES OpenGL one would tend to use the tessellator from the GL Utility (glu) library. I found this project which aims to make glu available for the iPhone and it claims to support polygon tessellation - if it works, then it would be a good option.