[ REQ 5576]: Geomview output incompatible with BMRT Renderman

[bobl at cs.ubc.ca]

I've been using Geomview to generate some images that make use of
transparency.  I create Renderman RIB files that then run through the Blue
Moon Rendering Tools (BMRT) Renderman package.  If I send my images directly
to BMRT's "rendrib", I get a large stream of messages like

	read character 91  "["

which suggests to me rejection by rendrib's parser.  In addition, the output
did not show any transparency.

I looked at the RIB file and found nothing that was obviously transparency
related until I saw the "Os" entries on the line after the Color declaration,
looking something like:

	Color [1 1 1] 
	"Os" [0.0588235 0.0588235 0.0588235] 

Just out of curiosity, I tried changing "Os" to "Opacity", as follows:

	Color [1 1 1] 
	Opacity [0.0588235 0.0588235 0.0588235] 

and, to my surprise, the image rendered correctly with transparency and no
complaints at all from "rendrib".

For my immediate purposes, the workaround is obvious, but I'm curious about
which product is at fault here.  I don't have an up-to-date Renderman spec,
so I can't check that.

Is this a Geomview bug?

	- Bob Lewis
	  bobl at cs.ubc.ca