<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type"> </head> <body bgcolor="#ffffff" text="#000000"> Aaron Plattner wrote: <blockquote cite="mid:20090525165448.GA4910@weasel.nvidia.com" type="cite"> <pre wrap="">On Mon, May 25, 2009 at 07:15:33AM -0700, Jerome Guilmette wrote: </pre> <blockquote type="cite"> <pre wrap="">Hi everyone, I hope this is the good list to send my question to for it is a rather a specific matter. All my tests were done using an NVIDIA GeForce 8600M, driver version 180.29, under the Fedora 10 OS. Here is my issue: I have a program that takes a few screenshots of an application (window) and saves it into a file. I discovered that, while taking a snapshot of an application running an openGL viewport, i.e. glxgears, and switching to another X server, I was not able to save the images in their integrity, the openGL viewport wasn't displayed. So the raw content of an openGL viewport isn't available while we are in another X Server than the one the program is running into. So would it mean that only one openGL context per X server is possible? </pre> </blockquote> <pre wrap=""> I'm not sure how you concluded that only one context per X server is possible from the fact that you can't access a window's pixels when the server is not on the active virtual terminal. You can definitely have multiple contexts per X server. </pre> </blockquote> I'm sorry, I didn't write what I wanted to, my question would have been more appropriate that way: So would it mean that we can only have active openGL contexts on the server that is currently active? As you answered, no openGL rendering can be done on an inactive X server. <blockquote cite="mid:20090525165448.GA4910@weasel.nvidia.com" type="cite"> <pre wrap=""></pre> <blockquote type="cite"> <pre wrap="">In a multiple X sessions context, is there a way to have access to the rendered openGL viewport pixels while being currently on a different X server using standard X functions? In any case, what exactly are the mechanisms in place? </pre> </blockquote> <pre wrap=""> No, you can't do that. When you VT-switch away from the current X server, all windows are clipped so that no rendering occurs to them, and OpenGL processing is suspended. The non-active X server is not supposed to touch the hardware at all, to allow the active X server to use it. </pre> </blockquote> I thought so, but, still, I was hoping for a way to do this. At least, I know it's not possible. I'm just asking if one of you guys might know: 1 - Is there any future plans for a way to access the hardware on multiple X sessions? What is the exact reason why only the active X server have access to the hardware through openGL? 2 - In this very case, I am bind to X, but, in a case not involving any X, nothing can't stop us from using another way than openGL to access the hardware on different X servers using, by example, CUDA? <blockquote cite="mid:20090525165448.GA4910@weasel.nvidia.com" type="cite"> <pre wrap=""></pre> <blockquote type="cite"> <pre wrap="">Any inputs would be very much appreciated, might it be a link to more documentation or a direct answer. </pre> </blockquote> </blockquote> Thank you for your time, Jerome </body> </html>