PhotoRealistic RenderMan
Application Note #7

THE PROBLEM

The Renderer currently uses a flat name space and a single symbol table for both its internal definitions and user declared parameters (shader arguments, vertex variables). This can cause problems when a shader argument has the same name as an internal renderer symbol, for example, "origin" as used in the Display command, and "origin" as used as a shader parameter. An RiDeclare can be inserted to change the type of "origin" to the type expected by the shader, but this will cause problems if a subsequent Display command is issued with the parameter "option" specified.

Certain names have been defined as parameters for the standard shaders and the appropriate RiDeclare issued for them. It is strongly recommended that the type of these shader parameters NOT be changed in order to preserve some degree of compatibility with the standard shaders.

PREDEFINED RENDERER SYMBOLS

The following names are reserved for the renderer and must never be used as the names for shader parameters:

GENERAL RI PARAMETERS

PREDEFINED SHADER PARAMETERS

The following shader parameters are pre-defined in the renderer and their types should not be changed:

SHADER PARAMETERS