Shading Language

Aqsis supports shaders written in the RenderMan Shading Language, RSL or simply SL for short. Shaders written for most other RenderMan implementations are compatible with Aqsis, and vice versa. Shaders written in SL are compiled by ‘‘aqsl’’ to an intermediate text-based format for efficient shader execution. The compiled shader format is unique to Aqsis, and not compatible with other renderers.

RSL Standard Conformance

Aqsis supports the following shader types defined in the RenderMan standard:

• Surface shaders
• Displacement shaders
• Light source shaders
• Volume shaders
• Imager shaders

All standard language constructs and RSL built-in functions are supported. Shaders written for other RenderMan-compliant renderers should compile and work with Aqsis. The RSL function trace() is formally allowed in shaders but always returns black, because Aqsis is a strict Reyes renderer and does not (yet) incorporate a ray tracing subsystem.

RSL Extensions

As an extension inspired by NVidia’s abandoned renderer Gelato, Aqsis also supports layered shaders, which enables the use of several separate shaders of the same type to compose a desired effect. Shaders are connected by using output variables from one as input variables to the next, in a flexible manner that allows shaders to work together even if they were not originally designed for that purpose.

The syntax of layered shaders is described in the article [[guide:layered_shaders|Layered Shaders]].