A. Ballard Andrews (ballard++at++sirius.ccd.bnl.gov)
Thu, 12 Jun 1997 16:31:52 -0400
The following messages are culled from the case which was closed
by SGI without reaching any resolution of the problem after a year:
"Performer's inventor-file-loader actually uses
the Inventor library to bring in the file; an Inventor scene graph is
built temporarily, and a traversal is done to tesselate the geometry
& send it to Performer's 'Builder'.
One of the Inventor engineers was able to track the problem down
to a bug in ivfix. To confirm this, load the file into
ivview and selected "Optimize for speed (ivfix)" under the Optimize
menu -- the result was that the same distorted colors came up in ivview.
What's happening is that ivfix is trying to put all the
material properties into the VertexProperty node, but that node
deals only with diffuse color and transparency. Since the rest
of the materials are thrown away, the colors look very different.
I'm now investigating to see if there is a method to turn off this
'ivfix' optimization in Performer's inventor loader, but haven't
found a solution yet. It may be something that is hardcoded within
the inventor library code."
I can't tell where the optimization is done in the loader
(there are no calls to ivfix), otherwise I would simply turn it off.
It seems like someone at SGI ought to feel compelled to
look at this problem. After all, SGI has promoted the inventor
format is as a 3D standard (VRML), so it seems not unreasonable
that SGI would hae its premier graphics software be able to
load such files without a hitch.
If anyone knows how to turn off the optimization, I'd
really appreciate your sharing this info with me.
Ballard Andrews
Brookhaven National Lab
Computing Division
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