Re: glXChooseVisual does not handle GLX_RGBA correctly
Geoff Levner wrote:
Larry Hall (Cygwin X) wrote:
Geoff Levner wrote:
I have an OpenGL-based application executing on a Sun, but displaying
on a PC running Windows XP and an X server. The app requires a
TrueColor visual, so when it calls glXChooseVisual, it passes
GLX_RGBA in the attribute list. This works fine with another X server
(Exceed), but when using Cygwin/X, glXChooseVisual fails to return a
visual.
Running xdpyinfo would seem to indicate that the server has *only*
TrueColor visuals (see the output below). And in fact if I remove
GLX_RGBA from the attribute list, glXChooseVisual does return one of
those visuals. If I ask for information about the visual with
glXGetConfig, it responds that color buffers store color indices
(GLX_RGBA is false), yet the application works correctly.
Anybody have a clue what is going on here?
Looks to me like you're app is looking for 32 bits while Cygwin-X is
only providing 24 bits. Unless you know you absolutely need
transparency, I think you'll find everything works fine with the
visuals you can get. Just ask for GLX_RGB instead.
That sounds reasonable, but GLX_RGB is not defined, and I can't find any
reference to it in the GLX 1.4 specifications. According to the
documentation, GLX_RGBA just means you want TrueColor or DirectColor
visuals; it says nothing about alpha. And we do not ask for any alpha
bits...
Yup, you're right. I was thinking of something else.
Perhaps it's just your combination of attributes. You might check that.
The combination below has worked for me before, albeit from a Linux
machine to Cygwin/X:
int visual_attributes[] =
{
GLX_DOUBLEBUFFER,
GLX_RGBA,
GLX_RED_SIZE, 1,
GLX_GREEN_SIZE,1,
GLX_BLUE_SIZE, 1,
GLX_DEPTH_SIZE,1,
GLX_STENCIL_SIZE, 1,
GLX_ACCUM_RED_SIZE,1,
GLX_ACCUM_GREEN_SIZE, 1,
GLX_ACCUM_BLUE_SIZE, 1,
None
};
--
Larry Hall http://www.rfk.com
RFK Partners, Inc. (508) 893-9779 - RFK Office
216 Dalton Rd. (508) 893-9889 - FAX
Holliston, MA 01746
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glXChooseVisual does not handle GLX_RGBA correctly
I have an OpenGL-based application executing on a Sun, but displaying on a PC running Windows XP and an X server. The app requires a TrueColor visual, so when it calls glXChooseVisual, it passes GLX_RGBA in the attribute list. This works fine with another X server (Exceed), but when using Cygwin/X, glXChooseVisual fails to return a visual. Running xdpyinfo would seem to indicate that the server has *only* TrueColor visuals (see the output below). And in fact if I remove GLX_RGBA from the attribute list, glXChooseVisual does return one of those visuals. If I ask for information about the visual with glXGetConfig, it responds that color buffers store color indices (GLX_RGBA is false), yet the application works correctly. Anybody have a clue what is going on here? Thanks, Geoff Output from xdpyinfo: number of visuals:4 default visual id: 0x22 visual: visual id:0x22 class:TrueColor depth:24 planes available colormap entries:256 per subfield red, green, blue masks:0xff, 0xff00, 0xff significant bits in color specification:8 bits visual: visual id:0x23 class:TrueColor depth:24 planes available colormap entries:256 per subfield red, green, blue masks:0xff, 0xff00, 0xff significant bits in color specification:8 bits visual: visual id:0x24 class:TrueColor depth:24 planes available colormap entries:256 per subfield red, green, blue masks:0xff, 0xff00, 0xff significant bits in color specification:8 bits visual: visual id:0x25 class:TrueColor depth:24 planes available colormap entries:256 per subfield red, green, blue masks:0xff, 0xff00, 0xff significant bits in color specification:8 bits -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://x.cygwin.com/docs/ FAQ: http://x.cygwin.com/docs/faq/
Re: glXChooseVisual does not handle GLX_RGBA correctly
Geoff Levner wrote: I have an OpenGL-based application executing on a Sun, but displaying on a PC running Windows XP and an X server. The app requires a TrueColor visual, so when it calls glXChooseVisual, it passes GLX_RGBA in the attribute list. This works fine with another X server (Exceed), but when using Cygwin/X, glXChooseVisual fails to return a visual. Running xdpyinfo would seem to indicate that the server has *only* TrueColor visuals (see the output below). And in fact if I remove GLX_RGBA from the attribute list, glXChooseVisual does return one of those visuals. If I ask for information about the visual with glXGetConfig, it responds that color buffers store color indices (GLX_RGBA is false), yet the application works correctly. Anybody have a clue what is going on here? Looks to me like you're app is looking for 32 bits while Cygwin-X is only providing 24 bits. Unless you know you absolutely need transparency, I think you'll find everything works fine with the visuals you can get. Just ask for GLX_RGB instead. -- Larry Hall http://www.rfk.com RFK Partners, Inc. (508) 893-9779 - RFK Office 216 Dalton Rd. (508) 893-9889 - FAX Holliston, MA 01746 -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://x.cygwin.com/docs/ FAQ: http://x.cygwin.com/docs/faq/
