Re: [CinCVS] Why OpenGL does not affect rendering, It just accelerates playback?

[Johannes Sixt]

> May I ask why OpenGL does not affect rendering, It just accelerates
> playback? What is the reason?

The reason is that by the time rendering takes place there is no guarantee 
that a connection to an X server is available. Think of renderfarms.

-- Hannes

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Re: Re: [CinCVS] Why OpenGL does not affect rendering, It just accelerates playback?

[toby]

Craig,

I think it should be possible to get rendered output without the use of
proprietary toolkits. Plain OpenGL should do as well by rendering into a
(hidden)
texture and calling something like glGetTexImage() to access the
rendered output.
I'm not an OGL programmer, but I've read about this kind of techniques
many times. glReadPixels() provides basic access to the
actual "frame buffer" of the rendered screen content. But since
the output window might not be at full resolution,  this is not a solution.

In general,  it should be possible to make use of OpenGL for rendering, too.
Just look at all the OGL based hardware-acceleration stuff they're
working on
for vector libraries like cairo/glitz.

Toby



> Hi Craig,
>
> I don't understand what you said. I thought that nvidia cg offers frame
> buffer object to read data back from graphics card.
>
> Regards
> Leigh
>
> -Original Message-
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] Behalf Of Craig Lawson
> Sent: Monday, 12 March 2007 8:29 p.m.
> To: cinelerra@skolelinux.no
> Subject: Re: [CinCVS] Why OpenGL does not affect rendering, It just
> accelerates playback?
>
>
> The graphics processor on the video card is not designed to send
> rendered output back to the main processor. OpenGL instructions come in
> one end, and rendered output goes out the other end ... to the monitor.
>
> It's unfortunate we can't intercept this data. Solid modelers such as
> Blender could probably use it, too. Maybe someday there will be enough
> market demand for the hardware to change.
>
> Craig.
>
>
> Leigh Wanstead wrote:
> > Hello everyone,
> >
> > I read this url.
> >
>
http://cvs.cinelerra.org/docs/split_manual_en/cinelerra_cv_manual_en_3.html#
> SEC41
> >
> > May I ask why OpenGL does not affect rendering, It just accelerates
> > playback? What is the reason?
> >
> > TIA
> >
> > Regards
> > Leigh
> > www.smootharm.com <http://www.smootharm.com/>
>
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Re: [CinCVS] Why OpenGL does not affect rendering, It just accelerates playback?

[Stefan de Konink]

Hi,

Leigh Wanstead wrote:

I don't understand what you said. I thought that nvidia cg offers frame
buffer object to read data back from graphics card.


You are correct Cg and BrookGPU both use the GPU as extra processing 
unit. But you should wonder a few things: is floating point what you 
want for calculations, if so what would be faster GPU/CPU and what would 
be more compatible.


It is nice to code for an Ati or nVidia chipset. But you tighten 
yourself to those implementations. It isn't strange if it only works 
with close source drivers. Other users can benefit more from MMX/SSE/etc.


I think if someone created proof-of-concept plugins using the GPU it 
would be good to compare. When I was working on BrookGPU for 
benchmarking a libm on GPU we found out that a lot of time was spend in 
actually transferring the data from and to the graphics card. The GPU is 
a great 'reduction' machine. Maybe stuff changed :)




Stefan

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RE: [CinCVS] Why OpenGL does not affect rendering, It just accelerates playback?

[Leigh Wanstead]

Hi Craig,

I don't understand what you said. I thought that nvidia cg offers frame
buffer object to read data back from graphics card.

Regards
Leigh

-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Behalf Of Craig Lawson
Sent: Monday, 12 March 2007 8:29 p.m.
To: cinelerra@skolelinux.no
Subject: Re: [CinCVS] Why OpenGL does not affect rendering, It just
accelerates playback?


The graphics processor on the video card is not designed to send
rendered output back to the main processor. OpenGL instructions come in
one end, and rendered output goes out the other end ... to the monitor.

It's unfortunate we can't intercept this data. Solid modelers such as
Blender could probably use it, too. Maybe someday there will be enough
market demand for the hardware to change.

Craig.


Leigh Wanstead wrote:
> Hello everyone,
>
> I read this url.
>
http://cvs.cinelerra.org/docs/split_manual_en/cinelerra_cv_manual_en_3.html#
SEC41
>
> May I ask why OpenGL does not affect rendering, It just accelerates
> playback? What is the reason?
>
> TIA
>
> Regards
> Leigh
> www.smootharm.com <http://www.smootharm.com/>

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Re: [CinCVS] Why OpenGL does not affect rendering, It just accelerates playback?

[Craig Lawson]

The graphics processor on the video card is not designed to send
rendered output back to the main processor. OpenGL instructions come in
one end, and rendered output goes out the other end ... to the monitor.

It's unfortunate we can't intercept this data. Solid modelers such as
Blender could probably use it, too. Maybe someday there will be enough
market demand for the hardware to change.

Craig.


Leigh Wanstead wrote:
> Hello everyone,
>  
> I read this url.
> http://cvs.cinelerra.org/docs/split_manual_en/cinelerra_cv_manual_en_3.html#SEC41
>  
> May I ask why OpenGL does not affect rendering, It just accelerates
> playback? What is the reason?
>  
> TIA
>  
> Regards
> Leigh
> www.smootharm.com 

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[CinCVS] Why OpenGL does not affect rendering, It just accelerates playback?

[Leigh Wanstead]

Hello everyone,

I read this url.
http://cvs.cinelerra.org/docs/split_manual_en/cinelerra_cv_manual_en_3.html#
SEC41

May I ask why OpenGL does not affect rendering, It just accelerates
playback? What is the reason?

TIA

Regards
Leigh
www.smootharm.com