Even on a surface closest to the light source, you will always discover minor differences in the values associated with the R texture coordinate(...). This can result in "surface acne"(...). You can mitigate this problem by applying a depth offset when rendering in the shadow map:That balance is not so easy to achieve; as Nvidia says in its papers, it's really matter of art.
glPolygonOffset (factor, 0.0f);
(...)A balance need to be struck when it comes to polygon offset usage.
from OpenGL superbible 4th edition by Richard Wright (Wesley).
Friday, 19 September 2008
Young 3D engines suffer acne
As the engine grows up, I refactor some routine. Cleaner code allows me to use some higher level function, like a 3Ds objects loader. And here appears a well-know issue: z-fighting.