[vtk-developers] GLXPixmap vs OSMesa
Jeff Lee
jeff at cdnorthamerica.com
Thu Mar 10 17:01:49 EST 2005
Hi All,
I have been tooling around with glpixap for offscreen rendering. I
started with vtkXOpenGLRenderWindow and managed to strip out the osmesa
stuff and replace its implementation with rendering to a glxpixmap
instead (a'la John Schalf and Glenn Lehmann). All of this works great,
all I have to do is call SetOffScreenRendering(1) on the renderWindow,
and then I can dump the image to a file. Eventually I can have it such
that switching between onscreen/offscreen will work similar to windows.
I can also see a pbuffer implementation as a straightforward extension
of this.
The question is, can anyone see any major drawbacks of dropping osmesa
for this approach? The benefits that I can see are;
1. No more mangled mesa, this approach (glxPixmap) works both in
mesa and in hardware drivers.
2. We can stop tiling the display to get high-resolution images.
3. Similar behavior to that of vtkWin32OpenGLRenderWindow.
4. Can further extend to hardware-accelerated pbuffers with drivers
that support it.
Possible Drawbacks:
1. Perhaps not everyone has a driver which supports glx1.3.
2. glxpixmap is slow (not when compared to osmesa).
I would like to eventually replace what's in vtkXOpenGLRenderWindow with
glxpixmap. Does anyone have other arguments which I am perhaps not
seeing, or reasons for not doing this? Thanks in advance.
Regards,
Jeff
--
Jeff Lee
Senior Software Engineer
Computational Dynamics North America Ltd
21 Lafayette Street, Suite 230
Lebanon NH 03766 USA
fax: 603 643 9994
phone: 603 643 9993 x109
http://www.cd-adapco.com
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