PseudoColor and DirectColor visuals (was Re: Documentation?)

Patrick O'Donnell pao at
Thu Apr 9 09:21:50 PDT 2009

>Date: Thu, 09 Apr 2009 11:17:25 -0400
>From: Peter Harris <pharris at>
>Patrick O'Donnell wrote:
>> (Supporting TrueColor, alas, would be a royal pain, given the design
>> of the apps.)
>... use an OpenGL fragment shader to do the
>PseudoColor => TrueColor translation at CopyArea[1] time. ...
>Unfortunately, I don't know of a way to bind an X Pixmap into an OpenGL
>texture, so that may not help you any.

Thanks for the idea, but I think you're right that it probably is not
the direction to go.

>The RENDER extension already has mechanisms for copying PseudoColor
>pixmaps to TrueColor displays, but it does not allow you to use your own

This sounds a bit more promising, though.  I guess I'll have to read
up on RENDER.  Could you clarify "it does not allow you to use your own
colormap"?  Is there a default PseudoColor colormap (writable) that is
uses, or is it a fixed colormap, and it's thus not really PseudoColor
conversion that it's doing but StaticColor.

		- Pat

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