Questions specific to rendering Mental Ray in ShadeTree.

    
    You need to have the C++ compiler installed. At your SGI's unix
    prompt, type:

	[you@IRIS]: versions | grep -i c++.compiler
	I  c++_dev.man.c++      12/06/95  C++ Compiler Man Pages
	I  c++_dev.sw.c++       12/06/95  C++ Compiler

    Is ray.irix5 in your path? In your shell, type:

	ray.irix5 -version

    This should advertise which version of Mental Ray you're running.
    If you get 'ray.irix5: Command not found', then consult your sysadmin
    to make sure your Softimage environment is properly setup, and that
    Softimage has the Mental Ray option installed.

    Bring up the Render Options Editor (Render -> Render Options), and make 
    sure:

	> 'Trace' is on
	> 'Shadows' is on
	> 'Shadow Factor' is a value less than 1.0 (try 0.25)

    Make sure 'Para-Approx' in the Render Options Editor is set correctly.
    A value of 1.0 will give a shrink-wrap look for displacements. Crank this
    number up to slow your renders, but improve details in displacements.

    Unfortunately, the 'patch' is made of 4 vertices, whereas the sphere
    has many vertices.

    This means you need to set your parametric approximation to a high number
    on patches (like 200), and adjust it down to a lower number on the sphere
    (like 10) to get similar results.

    If the ShadeTree patch had the same number of verts as the sphere, this
    wouldn't be necessary, but sometimes it's good to compare how a lores 
    object reacts to a shader. <I>Ok, it was a mistake, I admit it ;)</I>

    Same reason as above. 
    
    When rendering on the patch, set your parametric approximation to about 
    20x the value you use on spheres and cylinders.

    Questions specific to writing shaders.