The random material allows you to randomly assign a set of five materials, with a given importance (probability), to a set of objects. This is useful to randomly assigned materials to trees, buildings, props, etc. It is possible to chain this material to assign more materials.
Material[1...5]
Specifies the material to use
Importance[1..5]
Specifies the importance, relative to all other materials, of this material. Note that importance doesn't have to be in the [0..1] range.
Seed
A random seed to produce different variations for the same sert of parameters.
