One way to reduce noise for ao occlusion is to do blur the occlusion values.
8 Samples, Blur-value:0
8 Samples, Blur-value: 2
With this patch, this can be done by using the 'Blur' slider below the sample control. (defaults
to 2, 0 means no blur)
The way this is done currently is by splitting up the 'clay' pass (which uses clay_frag.glsl) into two passes:
One that does the occlusion checks and stores them into the color buffer(r: cavity, g: edges).
We then blit the color buffer into a temporary texture and use it for the second pass, which does the actual
materials and blurs+applies the ao from a texture.
As a result of this, we have to draw the scene 3 times. Doing deferred shading would solve this, but I don't
know whether there are any changes to the material system on the radar, in which case it would probably be
better to wait first.
Another solution would be to do the depth prepass and AO pass in one go, however that would still mean have
to draw the scene twice. Also, we'd have to do unnecessary ao calculations where triangles overlap on the screen.