Celestia Forums

Any chance that nebulae can be made separate from galaxies in future? It would be nice to have a way to view one without having to view the other, as having them both on at the same time seems to seriously slow Celestia down.

I've got 1 GB of RAM in my PC and a 128MB graphics card, and while I can generally view Runar's Billow Maidens addon with no problem, as soon as I have both the Triffid Nebula and the Milky Way in the same view it gets all jerky. I suspect that if there was a way to view just the nebula by itself (without the milky way) then I might not have this problem.

Maybe you could do this by having an option to view only meshes instead of meshes + galaxies?

Oh, Evil One,

I agree that being able to select either Galaxy or Nebula rendering would be very useful, whether or not it's a performance issue.

You can test your performance hypothesis by eliminating the Galaxies and/or the Nebula.

To eliminate the Galaxies that come with Celestia, rename the file
Celestia\data\deepsky.dsc to be Celestia\data\deepsky.dscNO

To eliminate the Triffid Nebula, drag its folder to a directory outside the Celestia directory.

Do either or both of these changes make a difference?

Um. On further checking, it seems to be the trifid nebula itself that is slowing things down.

Though I remember that when I had your deep space galaxies addons installed, they slowed things down quite a bit too.

So maybe my reasoning was off a bit, but it would still be nice to split nebulae from galaxies anyway...

Oh, Evil One,

I suspect that the reduction in frame rate (that's what it is, right?) is due to obscuration tests that are done by Celestia's code before it tells the graphics card what to draw. When there are a lot of objects in view in front of the Nebula, things tend to be slow.

What frame rates are you seeing with and without the Nebula?
What speed of CPU do you have?

selden wrote:Oh, Evil One,

I suspect that the reduction in frame rate (that's what it is, right?) is due to obscuration tests that are done by Celestia's code before it tells the graphics card what to draw. When there are a lot of objects in view in front of the Nebula, things tend to be slow.

What frame rates are you seeing with and without the Nebula?
What speed of CPU do you have?

Yeah, it's frame rate that I'm talking about... (I didn't know Celestia had a frame rate counter!).

OK. I'm at the usual start location around Earth, and all I'm rotating the view around it. My frame rate with Galaxies turned off is about 62 fps. When I turn the Galaxies option on, the fps drops to about 35-40 - which is odd, considering that I'm not even moving the viewpoint when I do this.

Aha. It's not the Trifid Nebula at all - It's (Rassilon's? Jestr's?) Antares nebula addons that are the problem!! When I've got those installed, the frame rate plummets to about 8, and the motion gets VERY jerky as I move. As soon as I removed them, the frame rate is fine (even when I go right up to Ran and look at the Trifid nebula, the frame rate is between 40 and 70. The Antares nebulae were behind the Trifid though, which is why it was jerking to a halt before.

(oh, CPU is a 2.4 GhZ Athlon XP 2100+)