Small surface perturbations can be supported by means of displacement shaders. Typically, a displacement shader will give an irregular or indented appearance to an otherwise smooth surface by modifying the surface normal vector that is used in subsequent shading calculations.
Displacement shaders are used to represent features that would be difficult, impossible or inefficient if conventional modeling techniques were used. For example, rough metal castings and the regular indentations produced by pressed sheet metal can be simulated.
We provide herewith names and descriptions of displacement shaders:
"casting"
A cast metal-like finish.
"rough"
A rough, undulating finish.
"wrapped bump map"
A bump map displacement derived from an image file.
"wrapped dimple"
A regular dimpled appearance.
"wrapped knurl"
A knurled appearance.
"wrapped rough"
A wrapped rough, cast metal-like finish.
"wrapped tread plate"
A tread plate pattern.