[GRASS-dev] Re: [GRASS GIS] #104: saving display to tiff or ppm garbled when NVIZ is not top window

Glynn Clements glynn at gclements.plus.com
Wed Mar 26 09:20:54 EDT 2008

GRASS GIS wrote:

> #104: saving display to tiff or ppm garbled when NVIZ is not top window

>  > The only reliable way to generate image files using OpenGL is to render
>  to an off-screen target such as a pBuffer or GLXPixmap. But those require
>  support from the driver, and we haven't had much luck with either approach
>  Actually, using a GLXPixmap works fine for me with both Cygwin's XWin.exe
>  and X.org with the "nv" driver (that's the FOSS driver with no DRI/DRM
>  support; I haven't tried the proprietary "nvidia" driver yet).

In light of this, I suggest re-considering whether a GLX Pixmap should
be used by default for 6.3.0. Currently, a GLX Pixmap has to be
specifically enabled by setting GRASS_GLX_PIXMAPS (whereas the trunk
requires it to be specifically disabled by setting

If it turns out that GLX Pixmaps work on a significant proportion of
systems, they should probably be used by default, as they don't suffer
from the inherent problems of trying to read a window's contents
(clipping, occlusion, the window receiving events in the middle of
rendering, etc).

I say "a significant proportion" rather than "the majority", because
the situation is likely to get better (rather than worse) over time. 

Glynn Clements <glynn at gclements.plus.com>

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