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Date: Wed, 03 Sep 2008 22:00:31 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] [PATCH] opengl rendering in the sdl window
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To: qemu-devel@nongnu.org

Stefano Stabellini wrote:
> This patch comes from xen-unstable and adds opengl support for rendering
> the guest framebuffer in the SDL window.
> SDL is needed anyway to open the window and handle the events.
> Opengl rendering is optional and can be turned off at both compile time
> and run time (--disable-opengl).
> Some of the benefits of using opengl are:
>
> -faster rendering, less CPU intensive, especially with good graphic
> cards;
>   

Have you measured this or is this just intuition?  I've measured it with 
gtk-vnc and I did not observe any CPU usage decrease in using OpenGL for 
rendering verses an XShmImage.

> -makes the window resizing possible and hardware accelerated, thus very
> efficient and smooth;
>   

This is neat, but, I'm unsure if the right way to support OpenGL is 
through SDL.  For instance, there were Cocoa OpenGL patches posted a bit 
ago that would be largely similar.  It may make more sense to have an 
OpenGL front-end that has conditional code for SDL/Cocoa/X/etc.

Then again, I've been kicking around the idea of doing a GTK front-end.  
An obvious thing to do here would be a glext based OpenGL version (as we 
do in gtk-vnc).

I think we need to have some discussion about what the long term 
front-end should be for QEMU.  Otherwise, we're going to end up with a 
proliferation of front-ends.  Personally, I'd rather move from SDL to 
GTK so that we can build a proper user interface.

Regards,

Anthony Liguori