Celestia freezes on saturn, uranus and neptun???

[obiweb]

Hi

I'm new to celestia, so sorry if the answer is obvious. Celestia runs smooth on my computer (2800 mhz - Radeon 256Mb graphichs - 500Mb RAM). But - when these three planets are in view, celestia slows down extremely. I have not changed anything (textures, settings or whatever).

Can anyone help?

Thanks!

[selden]

Try turning off Ring Shadows to see if that helps.

You don't mention which model of Radeon card you have. My guess is that it's one of the lower models that doesn't have the 3D OpenGL hardware features that Celestia uses to draw Ring shadows. Software OpenGL operations are slow.

[obiweb]

Thanks!

That solved the problem. My graphics-card is Radeon 9200 SE. Would you be kind to tell me if this missing 3D OpenGL hardware support limits any other features than this?

[selden]

Obiweb,

Unfortunately, I'm not that familiar with the details of the hardware support in the various 3D graphics cards, although I do know that the lower numbers don't have as much as the higher numbers.

The major OpenGL feature that new versions of Celestia use is called "vertex shading". This provides surface shadows and specular reflections. My impression is that ATI has been struggling to get it right. Some of the older (smaller number) cards don't have it at all.

Please take a look at http://www.lns.cornell.edu/~seb/celestia/textures.html#3.2.
It shows how to see if your card supports vertex shading.