Angus Dorbie (dorbie++at++bitch.reading.sgi.com)
Mon, 25 Nov 1996 18:21:55 +0000
This is multisample transparency working on an antialiased visual vs
blended transparency on a non antialiased visual.
On RE2 you can improve things by sorting geosets and culling alpha pixels.
You could even try a lower resolution framebuffer to give a bigger pixel
depth.
On iR you should be able to select a different visual to get multisample
transparency. The secret with small pixel depth is to request a 15 bit
zbuffer. I think the safe strategy is to ask for a 1 bit Z which delivers
the best available given other attributes.
Cheers,
Angus.
On Nov 25, 6:00pm, David Nouls wrote:
> Subject: Problems with Alpha blending
> Hello Performers,
>
> We are having problems with alpha blending. When I load an object with a
> texturemap with alpha values on one onyx (RE2 - 4 RM4) it looks right,
> when I load it on an other onyx(RE2 - 1 RM5) it looks like the polygons
> are not sorted right. I have the same phenomenon on an Onyx with IR and
> 1 RM6. What could be causing this. BTW: I used perfly for testing on
> both machines.
>
> I looked at the gfxinfo on both machines:
>
> Working Onyx:
> dnouls++at++donald ~ % /usr/gfx/gfxinfo
> Graphics board 0 is "REV" graphics.
> Managed (":0.0") 1280x1024
> Display 1280x1024 ++at++ 72Hz
> 12 GE (GE10 rev. 0x7)
> 4 RM4 boards
> Large pixel depth
> 10-bit RGBA pixels
> Not using Multi-Channel Option
> Graphics board 1 is "REV" graphics.
> Managed (":0.1") 770x576
> Display 770x576 ++at++ 25Hz interlaced
> 12 GE (GE10 rev. 0x7)
> 4 RM4 boards
> Large pixel depth
> 10-bit RGBA pixels
> Not using Multi-Channel Option
>
> Not Working Onyx:
> Graphics board 0 is "REV" graphics.
> Managed (":0.0") 1280x1024
> Display 1280x1024 ++at++ 72Hz
> 12 GE (GE10 rev. 0x7)
> 1 RM5 board
> Small pixel depth
> 10-bit RGB pixels
> Not using Multi-Channel Option
>
> In this I can see that we are not using RGBA-pixels so I changed the
> resolution to a lower one and then I get 10-bit RGBA pixels. But still
> this doesn't solve my problems.
>
>
> /)avid
> --
> ( I had a .sig once, but a little green man beat me up and took it.)
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>-- End of excerpt from David Nouls
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