Attenuation

Shadow Maps are applied only inside the Light frustum. Pixels outside the Light's frustum are not affected.

The shadows can have a fade effect that mimics the Light lighting ranges (defined by parameters such as Attenuation, HotSpot).

This fade effect can control the fade effect with the light.shadow\attenuation parameter.

Image example

• Left image: The attenuation = 1 à The shadow uses the same attenuation equation of the lighting algorithm.

• Right image: The attenuation = 0 à The shadow it is always at the maximum alpha value specified for this Light.

  

Exclude Back Faces

Consider any Mesh triangle that is not facing the Light to be shadowed without requiring Shadow Maps, because it does not receive any color from the Light.

Because the shadows application shader runs globally on all the Scene pixels (and not on single triangles), the application must check which triangles must be shadowed.

The global parameter, shadowMaps\excludeBackFaces, prevents these back-facing triangles to be darkened twice: once because they receive less light, and a second time when the shadow is applied.

This parameter is switchable because in other lighting setups it may give better results to have shadows applied also to these triangles.

Note: The Shader has fewer instructions when this feature is turned Off. In theory, the code runs faster.

Image example

• Left image: The excludeBackFaces parameter is On.

• Right image: The excludeBackFaces parameter is Off.