Drawing of concave polygon

[Dark_Photon]

I looked this up at one point. Here’s a link to some docs on the gluTess routines, and also to an alternative using the stencil buffer that lets you render concave polygons without tessellation.

Fill Polygons according to winding number rules

Here’s a really old FAQ that has a section on the GLU tessellator routines. Search for “concave” in here: LINK. As for the concave polygon rasterization algorithm GClements mentioned, here’s a short write-up on that: Drawing Filled, Concave Polygons Using the Stencil Buffer. Yes , do keep in mind with modern OpenGL you don’t need multiple stencil passes for this anymore.