I know it would be difficult, but I think it is not totally impossible, althought it would require important changes such as:
 - using Cairo as a renderer: unlike many openGL applications, we use almost exclusively 2d openGL rendering since we compute the projection of most of the vertex on the CPU, so moving to a 2D renderer like Cairo is not totally impossible for us.
 - removing things that are continuously animated (or optimize the rendering so that only them are refreshed) so that the framerate of 0 FPS would be acceptable when user don't interact
 - Use a degraded rendering when the user interacts to keep the movements fluid (like display less stars).
 - use lower resolution textures and optimize texture loading (lazy loading using ram/disk/network multi-stage cach)
 - use a smaller star catalog
 - have a lower quality atmosphere rendering (less points computed)
 - use a less accurate and simplified planet position algorithms

I am sure that alltogether, the framerate could reach something fast enough to be useable, even on OLPC. Some of the features could even be very useful for the normal version: a Cairo renderer would allow to export images in PDF very easily, and the multi stage texture caching would improve loading speed and reduce memory consumption.

Fabien

On 9/20/07, Johannes Gajdosik <johannes.gajdosik@gmx.at> wrote:
On 2007.09.20 22:21:38 CEST, Fabien Chéreau wrote:
> Someone interested?
> Fabien

Quotation from the specs:
# CPU clock speed: 433 Mhz;
# Graphics controller: Integrated with Geode CPU; unified memory
architecture;
# DRAM memory: 256 MiB dynamic RAM;
An old notebook of my mother had 256MB ram, Pentium3 1GHz
and SiS accelerated 3D graphic. I managed to run stellarium,
although without constellation art (too big for loading).
The performance was 15FPS with properly installed DRI
driver and less than 1FPS with MesaSoft.
Since I cannot believe the Geode CPU has accelerated
3D graphic, I say it is hopeless. Just forget it.
Would be nice, but just forget it.

An approach without OpenGL would be needed.
KStars might work. Xephem certainly will.

Johannes


> ---------- Forwarded message ----------
> From: Thomas Jacobson < thomas@tcjnet.com>
> Date: Sep 20, 2007 4:09 AM
> Subject: Stellarium for the OLPC XO...
> To: stellarium@free.fr
>
>  Hi.
>
> Last week I gave a talk on networking and satellites to the MIT One
> Laptop
> Per Child group. (see www.laptop.org, www.olpcnews.com for gossip, and
> www.olpc.tv for some videos) The night before I had been laying under
> the
> clear dark sky at my cabin in Wisconsin, and it occurred to me that
> somebody
> ought to port Stellarium to the OLPC XO laptop. No doubt somebody like
> www.timothyferris.com would tell you how important it would be to
> children
> in the developing world.  I suggested this to several OLPC folks, and
> everyone agreed... it was an excellent idea, but they are totally
> swamped
> just getting the XO out the door with the basic functionally.
>
> The display on the OLPC is outstanding... and there may be some nifty
> tricks
> you could do to leverage its very high contrast high resolution
> screen...  I
> would bet that if someone in the Stellarium developer community were
> to
> offer to undertake a port, that the OLPC folks would supply an XO or
> two to
> do it on...
>
> I think the OLPC website has information on how to propose such a
> project.
>
> Good luck!
>
> Thomas Jacobson
>

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