Re: 5 vs. 8-bit color
Phil Keslin (philk++at++cthulhu.engr.sgi.com)
Tue, 16 Mar 1999 09:54:46 -0800
DAVE HOATSON wrote:
>
> In my Performer application, I can*t seem to get the system (an O2) to render in 8-bits per color component. The result looks like 5-bits per color.
>
> I am using *glXChooseFBConfigSGIX* and *glXGetVisualFromFBConfig* to specify the frame buffer window. If I specify that I want double buffering, the only available configurations are 5-bits per color, while if I specify no double buffering, I can get 8-bits per color. Why does the realtime application look good even when the frame buffer is not double buffered? Also, when I use an 8-bit per color frame buffer, the end result still appears to be only 5-bits per color. I can use *glDisable(GL_DITHER)* to turn off dithering, but this gives me a banded image where the pixel values still jump in increments of 8, indicating 5-bit color.
Your framebuffer is configured for 32 bit visuals therefore
doublebuffered visuals only get 16 bits per pixel (5-5-5-1 per RGBA
component). You need 32+32 to get the 8 bit components. There is a
utility called xscreen that will allow you to reconfigure your
framebuffer. I don't think there is a man page for it, but the tool
should have most of the information you need.
- Phil
--
Phil Keslin <philk++at++engr.sgi.com>
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on Tue Mar 16 1999 - 09:55:13 PST