Fix SSAO or find alternative

[xycaleth]

I believe SSAO is broken at the moment and/or impacts FPS quite a lot.

Need to investigate whether this is worth fixing, or if there are better alternatives.

[SomaZ]

SmileTheory changed the ssao shader in the ioquake repository. maybe you want to look over the changes he made.

[DT85]

I say just dump it if it's not performing well and just put HBAO as a possible distant future enhancement.

[SomaZ]

I guess the SSAO performs so badly because you have to compute the normals of the scene (also multiple times) instead of getting them in the first place. Another guess is that there is no real fix for it right now. The hbao shader i wrote has some bugs right now, but with the help of xycaleth we might get it working properly.