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A traditional ambient occlusion effect can be accomplished by setting the occluded color to black and unoccluded color to white.
Occluded and Unoccluded
Resulting colors for occluded and unoccluded shading.
Controls the number of occlusion samples per camera hit point. More samples reduces can the noise at the cost of increased render time.
Possible values are uniform and cosine (Lambertian).
Sample spread of rays when using cosine distribution. A value of 1.0 gives a perfect Lambertian distribution.
Falloff values greater than zero create a softer look. Values less than zero give a hard edge when combined with max distance.
The max distance at which objects may occlude. Zero is infinite (all objects occlude).
Trace rays in the direction of the surface normal (outside), inverse to the normal (inside), or in both directions.
Add a directional bias to the normal vector. Values must be specified in world space.