Quickie this time. How do i make a polygon (triangle/quad) doublesided?

if you dont need different colors/textures on the front/back, just dont enable culling.

if you do, you will have to calculate if front or back faces you using the normal of the polygon (like backface culling, but instead of culling it, render it using "back facing" settings )....

maybe there are better ways, but i dont them =)