Slim File Format

Background
Global Context
Context Summary
Keyword Summary

Background 

We use the Slim file format to encapsulate the state of Slim and to represent Slim extensions.  The format is syntactically very simple and is based on the TCL programming language (see http://tcl.sourceforge.net/).  A TCL based parser can be built up quite trivially given the knowledge that each context, described below, supports a predefined set of legal commands.  This notion that a only a certain set of keywords is meaningful at a given point in the parsing process is fundamental to all file formats and can be represented in modern TCL (post 8.0) using TCL's namespace facility.  To write a TCL parser for the .slim file format, one could simply construct a number of namespaces each of which represents a parsing context and is comprised of a set of procedures which embody the set of keywords available in that context.   Each keyword is implemented as a procedure whose arguments can either be fixed or variable in number according to standard TCL practice.  Now, in order to parse a file, one must simply source it into the appropriate TCL context.  The implementations of the keyword procedure  must simply pull the arguments from their argument list and do something with them.  Where keywords are used to represent hierarchical structure, the implementation must also make recursive calls to TCL's namespace eval command.

But, hey, we've already written such a parser so why should you care about the details?  Suffice it to say that, well, people ask.  In any event, the syntactic structure of .slim files is so simple that it may not be necessary to actually parse them.   Simple sed or perl scripts could also be used to process them in interesting and automated ways.  In any event we've included a stripped down version of a .slim file parser here for your perusal.  Note that to put this parser to useful purpose you'll need to implement objects that accept all the messages and build up appropriate state.

But back to the task at hand.  What exactly is the .slim file format?  The first thing to keep in mind is that its actually just a TCL script.  As such it abides by all the standard TCL conventions for commenting, new lines, braces and quotes.  A .slim file is parsed by simply sourcing it into an appropriately prepared TCL interpreter.
 

Global Context 

At the outermost scope, a Slim file must contain one or more slim commands.  All slim data is nested within in the body of the slim command.  Here's the format of the slim command:

slim version type creator body

Here, type can be one of: extensions, palette or appearance.

And here's a skeleton of a .slim file containing an encapsulated palette:

slim 1 palette slim {
    palette plt1 {
        function shadingmodel "Blinn_80" "pixar,Blinn" {
            identity 0ZgCEW39ZIB00000
            description {Mimics the Maya Blinn shader.}
            master {$torShaders/$INSTANCENAME}
            previewinfo {
               shadingrate 5
               objectsize 1
               objectshape Sphere
               frame 1
            }
            parameter color SurfaceColor {
              default {0 .25 1}
              provider connection
              detail varying {}
              label {Surface Color}
              connection 0ZgCEW39Z-F00000
            }
           ... more parameters...
        }
        ... more functions and instances ...
    }
    ... more palettes ...
}

As you can glean from this example context is everything.  For example, the identity command is only meaningful in the context of an object that has an identity.  Palette commands are only meaningful in places where palettes are expected and not, for example, where parameters are expected.

The remainder of this document details the various parsing contexts and the commands, or keywords, that are meaningful in these contexts.   Keep in mind that,  while the .slim file format is rather general, it is used for three primary purposes:

1. To store Slim extensions - templates, custom UIs
2. To encapsulate the current Slim state
3. To encapsulate a single Slim appearance.

• the output of the toslim utility program.   When you import a .slo file, Slim uses the toslim utility to generate temporary .slim files.
• the templates that ship with the system.   These can be found at $RATTREE/lib/slim.
• the results of saving one of your palettes.