HyperShade, RenderMan and Slim use different words to describe
similar concepts. For example, the words shown in bold are equivalent,
HyperShade - material
RenderMan - (surface) shader
Slim - appearance (but also applies to volumes, lights & displacements)
Within its interface, slim does not directly refer to shaders. Instead, it refers to
appearances. From an artists point of view an appearance
is a node that can be connected to other nodes to make a shading network. An imported
appearance, on the other hand, appears as a "stand-alone" node that cannot be
linked to other nodes.
So, what are the diffences between imported and created appearances and
how do they compare to regular RenderMan shaders? The following chart
shows the distinction between an imported appearance and a created appearance - both of which
are called plastic.
- a required shader called plastic.slo and
- an optional file called plastic.slim.
- a file called shadingmodels.slim
What is plastic.slo?
- based on a source code file called plastic.sl
- its a pre-compiled RenderMan shader
- contains info only prman can understood
- static (predefined functionality)
- its parameters can be set only by
explicit values, or
What is plastic.slim?
- a plain text file known as a slim appearance
- defines the GUI for the editor
(the calculations are done by the shader)
If the optional slim appearance file is missing Slim
defines a bare-bones editor for the shader - it may lack
some useful features needed by an artist.
What is shadingmodels.slim?
- not compiled
- a plain text file known as a slim template
- contains info humans can understand about
what its editor should look like (GUI), and
how it should calculate its output values
- dynamic (can be extended via connections)
- its parameters can be set by
connections to other slim files.
Slim generates, on-the-fly, a temporary .sl file that incorporates
the functionality in shadingmodels.slim and the other slim files to which it
may be connected. The temporary .sl file is compiled into a
RenderMan shader by Slim when the preview icon is updated (clicked).
© 2002- Malcolm Kesson. All rights reserved.