how do divide a simple,non-monotonic polygon into a set of monotone polygons in openGL? jjia83@yahoo.com

Monotonic? Do you mean convex? If so, it has been discussed on this list and others. Otherwise, what do you mean by monotonic?

If memory serves, a function is “monotonic” if the first derivative doesnt change the sign, so I think he means a non-planar polygon where the tangent does change the sign, I may be wrong though.

Anyway any non-planar, non-convex polygon needs to be tesselated into triangles (which are naturally convex and planar) by either using a gluTesselator or a user supplied function.

thank you for reply me.

actually i wanna know how to write a code to divide a simple, non-monotonic polygon into a set og monotone polygons.

it used to have merge vertices and split vertices.

i only know the theory about it but dunno how to write a code in openGL.

anyone can help?

thank a lot.