Ambient occlusion is a shader-driven effect which is probably best described as a crude version of Global Illumination. It's ( with rare exceptions) a static, precomputed effect so it only works on static geometry. Essentially, areas of a mesh which are occluded by geometry ( the self same object or another ) between it and the lightsource ( hemispherical, like a sunlight ) are darker than areas which are open and not occluded.
It's then normally mixed with a dynamic lighting solution like normal or parallax mapping. If you weren't going to mix it with a dynamic lighting solution, you might just as well precompute vertex or even lightmapping in Gile[s] and leave it at that.
It's then normally mixed with a dynamic lighting solution like normal or parallax mapping. If you weren't going to mix it with a dynamic lighting solution, you might just as well precompute vertex or even lightmapping in Gile[s] and leave it at that.