Light Path Expressions
Cutter


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Links:
    Pixar Doc (version 20)
    Pixar Doc (version 21)
    OSL Light Path Expressions
    Towards Bidirectional Path Tracing at Pixar



Introduction

This tutorial provides an overview of Cutter's support for scripting Light Path Expressions (LPE). Another tutorial,

    "RifPlugin: LPE"

explains how LPE's can be conveniently tested without using the RenderMan Controls window.


Syntax Coloration

Cutter applies syntax coloration to the text of a document with the file extension ".lpe" - a sample of which is shown below. The following lpe's are those defined by RMS19.


trial.lpe


# specular
lpe:(CS<L.>)|(CD<L.>)|(C<RD>[DS]+<L.>)|(C<RD>[DS]*O)
      
# diffuse 
lpe:CD<L.>
  
# refraction
lpe:(C<T[S]>[DS]+<L.>)|(C<T[S]>[DS]*O)
   
# shadow
lpe:shadows;C[<.D'collector'><.S'collector'>]<L.>

The color scheme can be set in the Prefences window - figure 1.




Figure 1


Popup Menu

A popup menu (right mouse button) can be used to insert one of the standard LPEs. The "Quick Reference" menu item will open Cutter's internal browser with a barebones reminder of the LPE event and scattering tokens. The "Pixar LPE Documentation" menu item will open Pixar's documentation in the external browser.




Figure 2









© 2002- Malcolm Kesson. All rights reserved.