Re: FBConfig behaves weird!

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Sharon Clay (src++at++rose.asd.sgi.com)
Mon, 20 May 1996 04:43:57 -0700

+>---- On May 16, 12:24pm, Gilles Reymond wrote:
> Subject: FBConfig behaves weird!
->I am trying to properly configure my pipewindow's framebuffer under Performer
->2.0 plus IRIS-GL functions on an Infinite Reality machine.
->
->In the Draw process config callback, I issue, inspired by the "pipewin.c"
->sample program generously shipped along with Performer2.0 :
-> int FBAttrs[] =
-> {
-> PFFB_RGBA,
-> PFFB_DOUBLEBUFFER,
-> PFFB_DEPTH_SIZE, 24,

Ahhh - this could be it. Try 23 instead of 24.
If you do a glxinfo in a shell, you will notice
that iR provides 23 bits of Z.
In the future, Performer should be more robust at handling
this subtlty!

-> PFFB_RED_SIZE, 8,
-> PFFB_SAMPLES, 8,
-> PFFB_STENCIL_SIZE, 1,
-> None,
-> };
-> pfPWinFBConfigAttrs(pwin, FBAttrs);
-> pfOpenPWin(pwin);
-> pfTransparency(PFTR_HIGH_QUALITY);

This much looks fine

-> pfAntialias(PFAA_ON);

This you don't need - we do it by default.

-> pfAlphaFunc(PFAF_GREATER, 10);

This is no good in - the reference value needs to
be a float between 0 and 1. This is probably getting clamped to 1 by
the GL. I'm not 100% sure what the GREATER will do in this case - seems
like you should see nothing but maybe you are seeing all fully opaque
pixels.

->
->Well, if I just ask for FB info after that, using :
-> pfuPrintPWinFBConfig(pwin,0);
->I will get the following run-time message :
->
-> pfPipeWindow Framebuffer Configuration:
-> RGB_BITS: 8
-> ALPHA_BITS: 8
-> CI_BITS: 36
-> DEPTH_BITS: 0
-> MIN_DEPTH_VAL: 8192
-> MAX_DEPTH_VAL: 8388607
-> MS_SAMPLES: 8
-> STENCIL_BITS: 0
-> DOUBLEBUFFER: 1
-> STEREO: 0
->
->Where are my DEPTH_BITS and STENCIL_BITS gone now? The point is that my
->upcoming window is *not* antialiased and has some problems with transparency
->and z-buffering as well.

Hmmm. If all of the above does not help you,
can you try this in the sample program for IRIS GL and OpenGL
and see if you get thhe same results?

Hopefully your plan is to move to OpenGL for your iR application? :-)

src.

-- 
-----{-----{---++at++   -----{----{---++at++   -----{----{---++at++   -----{----{---++at++
Sharon Rose Clay (Fischler) - Silicon Graphics, Advanced Systems Dev.
src++at++sgi.com  (415) 933 - 1002  FAX: (415) 965 - 2658  MS 8U-590
-----{-----{---++at++   -----{----{---++at++   -----{----{---++at++   -----{----{---++at++

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