From: Vincent Pasqualato (vincent.pasqualato++at++oktal.fr)
Date: 09/07/2005 09:49:31
I have the man page for pfdConverterMode_flt (our SGI version of Performer
is rather old) and pfdConverterMode_flt(PFFLT_COMPUTENORMALS, PF_OFF) seems
to be the good function call.
But like you, I couldn't make it work (doesn't have any effect apparently).
By the way, all the test I make are done on Win 2000, with flt file in
version 15.6.
I tried some other mode change which I thought could affect the behaviour,
but none of them seems to be doing what I need.
Thanks for the advice.
Vincent PASQUALATO
----- Original Message -----
From: "Jason Daly" <jdaly++at++ist.ucf.edu>
To: "Vincent Pasqualato" <vincent.pasqualato++at++oktal.fr>
Cc: <info-performer++at++sgi.com>
Sent: Wednesday, September 07, 2005 4:13 PM
Subject: Re: [info-performer] Fw: Flt loader with shaders.
> Vincent Pasqualato wrote:
>
> >Hi !
> >
> >Trying to combine a shader program written in GLSL with a Performer scene
> >graph, we discovered that rendering an flt object with faces which are
flats
> >(no gouraud/interpolation, no vertex normals) gives us strange results :
> >The flt loader seems to try some computation of vertex normals, because
> >there is a variation of the normal we get from Open GL (in gl_Normal
> >parameter of the shader program) across the faces. Plus, this
interpolation
> >is buggy, resulting in very strange patterns of normals on the object.
> >If we transform our object in gouraud, and pre-compute the vertex
normals,
> >the rendering is OK, except we don't get the flat faces we would want.
> >Does anyone have a suggestion about this behaviour ? Is there an option
to
> >deactivate this normal computation ? Or is it correct, assuming the
classic
> >OpenGL pipeline doesn't take into account vertex normals when rendering
flat
> >faces ?
> >
> >
>
> There is supposed to be:
>
> pfdConverterMode_flt(PFFLT_COMPUTENORMALS, PF_OFF);
>
> but last time I tried, it didn't work.
>
> >Also, another problem with flt loader and Shaders is the fact that the
> >loader seems to make some pre-computation on vertex colors and face
> >materials : vertex colors seems to be multplicated by the diffuse color
of
> >the faces, and ambient and diffuse color of the face seem also to be
> >affected by the color of the vertex. Although this doesn't affect classic
> >OpenGL rendering, it is incompatible with our shader, which make a
different
> >use of this colors and need them untransformed.
> >
> >
>
> I think there's supposed to be a mode for this as well, but I can't pick
> it out just from the pfflt.h file (and it probably wouldn't work
> anyway). Performer used to ship with the pfdConverterMode_flt man page,
> but no longer. The loader is also several years out of date (I think
> it's only good for versions 15.7 and earlier). I know MPI stopped
> supporting their Performer loader a while ago, and SGI hasn't kept up
> with OpenFlight versions since 15.7.
>
> --
>
> --"J"
>
> "I'm a castaway stranded in a desolate land,
> I can see the footprints in the virtual sand."
> --Neil Peart
>
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