This node allows a surface to look different depending on whether it is seen through reflections, refractions, or GI. With this material you can get a fine control over the color bleeding, reflections, refractions, and shadows of the objects.
Environment Priority - this specifies how to determine the environment to use if a reflected or refracted ray goes through several materials each of which has an environment override.
Base - this is the material V-Ray will use while rendering the object.
GI - this is the material V-Ray will use while calculating the GI solution.
Reflection - this is the material V-Ray will use to render the object with, when the object is seen in reflections.
Refraction - this is the material V-Ray will use to render the object with, when the object is seen in refractions
Shadow - this is the material that will be used to render shadows cast from the object.
Environment - this is an environment override for the Base Material
