RSL functions that communicate between surface shaders and light shaders are solar(),illuminate(), and illuminance().
These functions create the light-projecting effect we've come accustomed to.
Since lights are shaders, they are capable of the same RSL functions that surface shaders perform.
Occlusion, color bleed, texture mapping, displacements - anything a surface shader can do a light shader can do as well.
Figure 01 is the simplest light shader - the ambient light.
Ambient lights hold no contraints for their lighting functions - meaning an ambient light source illuminates top and bottom - front and back.
|
|
Figure 02: Light Shader Tag in .rib |