Parameters for rendering test scenes from Eric Haines' "Standard
Procedural Databases" (SPD) project.

   http://www.acm.org/pubs/tog/resources/SPD/

The SPD programs output scenes in "NFF" format by default, so can be
input to snogray standard input by using -Inff option.

The scene lighting levels seem to be pretty much random, so use the
snogray -L option as appropriate to adjust (suggested values are given
below).

Note that the reference pictures on the website use povray, which by
default uses linear light falloff, not r-squared; snogray always uses
r-squared.


General invocation is like:

   ../spd3_13/teapot | snogray -Inff -L3 -s512x512 - /tmp/teapot.png


Here are lighting options for each scene, to match reference images:

   teapot	 -L3
   balls	 -L.4
   tetra	 -L15
   shells	 -L1500
   mount	 -L1000
   sombrero	 -L10


The "test:teapot" test scene also uses meshes generated by SPD; these
aren't included with the sources because the teapot mesh is very large.
To create them using an SPD distribution, assuming "../spd3_13" is the
directory the SPD distribution has been built in, use the following
commands:

   ../spd3_13/teapot -s 30 | nff-cvt -msh2 > teapot.msh

   ../spd3_13/teapot -s 8 | nff-cvt -msh0 > board1.msh

   ../spd3_13/teapot -s 8 | nff-cvt -msh1 > board2.msh



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