it's not meant to be realtime. the above screen took about 15 seconds to render for 640x480 and 8 rays per pixel. it was just an experiment. ambient occlusion is a kind of fake global illumination method you can also use with the renderers of tools like maya. i thought it maybe would be nice to record animations with 3dgs and then output movies with this method but getting good results without too much noise is harder than i thought. of course you could also mix in the textures of the geometry. it could also be used to bake the shadows into textures.

the tga just has to be 24bit and the same size as your screen resolution.