Proposed Shader Improvements

Overview

This document is a place to collect all proposals for shader changes/improvements/issues.

Issues

• When material is unloaded, the state of the Property may not get restored --- vtkProperty should keep an internal state of the property before the material was loaded and restore to that state when the material is unloaded.
• The XML attribute names could be a little clearer, some suggestions:

   -'ivar' refers to instance variables on vtk objects
   -'value' refers to numeric values or defined constants in the case of Cg transformation matrix settings.
   -'shader_var' refers to the name of particular hardware shader variables

   For the tags PropertyUniform, CameraUniform, LightUniform the current construction:
       <PropertyUniform value="Ambient" name="property.Ambient"> </PropertyUniform>
     would become:
       <PropertyUniform ivar="Ambient" shader_var="property.Ambient"> </PropertyUniform>

   For tages that describe values for ivars for vtkProperty:
      <PropertyUniform name="DiffuseColor" value="0.85 0.05 0.15"> </PropertyUniform>
    would become
      <PropertyUniform ivar="DiffuseColor" value="0.85 0.05 0.15"> </PropertyUniform>