Re: [Qemu-devel] [PATCH] opengl rendering in the sdl window

[malc <av1474@comtv.ru>]

On Fri, 5 Sep 2008, Stefano Stabellini wrote:

> Jamie Lokier wrote:
>
>>
>> Fwiw, in my experience with Xine and mplayer, drawing video updates to
>> the screen using OpenGL was quite a lot slower than drawing them with
>> XShmImage.  That needs colour conversion as video doesn't even use RGB.
>>
>> Probably OpenGL is faster on some hardware, and slower on some hardware.
>> Don't assume it's always faster.
>
>
> Yes, good point.
>
>
>> Yes it very much depends on the drivers and opengl implementation.  It
>> isn't always possible to map the guest framebuffer into video
>> (texture) memory, and also some opengl implementations are not
>> particularly fast at copying textures from CPU memory to texture memory.
>
>
> This is also true.
>
>
>> Another way to map guest framebuffer to video memory is the XF86DGA
>> extension, which is great when you can use it.  I think VMware uses it
>> in full-screen mode.
>
> I went with OpenGL because I wanted the accelerated window resize
> feature, and because I think it will give us more opportunities for
> further improvements (for example using PBOs as soon as they are
> supported by at least one open source graphic card driver).

I have code that uses PBO or PDR or XAMM, for cirrus it was always
on par with the standard SDL drawing speed wise, and i expected it
to be faster with VMWare SVGA, but back when i was musing with it
VMWare SVGA didn't quite work with Linux guests, then it was fixed
but i got carried away by different stuff. I can probably brush it
up and release if anybody is interested.

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