[SDL] accessing on video surface from two processes.

[Thomas Mueller]

Dear Alex,

Thank you very much for your reply.

My problem:

I would like to use SDL commands from a scripted environment. Precisely
I want to use "octave" (http://www.gnu.org/software/octave/) to produce
some SDL graphics.

Yours Thomas.

On Wed, 2006-06-14 at 13:31 -0400, Alex Volkov wrote:
> Thomas Mueller wrote:
> > I would like to access a video surface from a second process.
> 
> The short answer is you cannot, but see below.
> 
> > I would like to open a window in a program and leave it open for a while.
> > *SDL_SetVideoMode to opens a window and returns a pointer to access that
> window. 
> > How can I "draw things" from a second process on that window opened by
> > the first process ?
> 
> On many SDL-supported platforms a pointer is only valid within the process
> that created the pointer (or rather the memory area the pointer points to).
> This is due to Virtual Address space used by most modern OSes.
> On these platforms you would normally resort to some way of inter-process
> communication (like pipes) to deliver the rendering commands to the first
> process (the owner of the SDL surface). The first process essentially
> becomes a rendering driver for the second process.
> All of this is beyond the scope of SDL, however, and I would recommend
> finding a different solution to your problem (you did not say what the
> problem was, btw).
> 
> -Alex.
> 
> 
> 
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-- 
Thomas Mueller
Laboratory of Neurobiology @ UCL
phone: +44 (020) 7679 3905
email: t.mueller at ucl.ac.uk
WWW  : www.vislab.ucl.ac.uk