Rings

marshead · Post #1by **marshead** » 28.03.2002, 02:16

I looked over the bug reports and didn't see any reference to this, so I'll pass it on....

Whenever I look at a planet with rings (Saturn and Uranus), I notice that the more of the rinsg you see the (significantly) slower Celestia runs. It actually gets almost impossibly slow to use. It gets down to less than 1 fps when rotating around the planet or moving closer or farther. I never had this happen to me in 1.2.2.

Am I doing something wrong here, or is this a bug that may be generally unreported?

Thanks,

Marshead

Incognito · Post #2by **Incognito** » 28.03.2002, 06:56

What is your system specs? Perhaps your video card is not up to it

marshead · Post #3by **marshead** » 28.03.2002, 15:32

I don't REALLY think that it could be the system as it is really new. P4-1.6GHZ, 512mb ram, and an ATI Rage 128 PRO with 32 megs of ram.

Again, I did not have this problem with 1.2.2! I also downloaded the 1.2.4 preview last night and had the same problem with that as well.

Also, and I should have mentioned this as well, whenever I run with the elcipse shadows... it does the same thing. I have shut those down, and keep them that way so I can navigate around with something that resembles fluid motion.

Thanks for any input....

Marshead

Post #4by **chris** » 28.03.2002, 17:01

marshead wrote:I don't REALLY think that it could be the system as it is really new. P4-1.6GHZ, 512mb ram, and an ATI Rage 128 PRO with 32 megs of ram.

Again, I did not have this problem with 1.2.2! I also downloaded the 1.2.4 preview last night and had the same problem with that as well.

Also, and I should have mentioned this as well, whenever I run with the elcipse shadows... it does the same thing. I have shut those down, and keep them that way so I can navigate around with something that resembles fluid motion.

I suspect that the ATI Rage 128 PRO is falling back to software rendering for one of the blend modes. That's the first thing I can think of that would cause such a dramatic slowdown. What puzzles me is that it didn't happen with 1.2.2. It may also be related to some slightly tricky stuff I do with mipmaps for the shadows textures. I'll do some research on the Rage 128 PRO part to see if there are any well-known cases where it falls back to software rendering.

In the mean time, do you have the latest drivers for your card? If not, you should go here:

http://www.atitech.com/support/drivers/powered.html

and get a new one.

--Chris

Rassilon · Post #5by **Rassilon** » 28.03.2002, 20:16

marshead wrote:I don't REALLY think that it could be the system as it is really new. P4-1.6GHZ, 512mb ram, and an ATI Rage 128 PRO with 32 megs of ram.

Again, I did not have this problem with 1.2.2! I also downloaded the 1.2.4 preview last night and had the same problem with that as well.

Also, and I should have mentioned this as well, whenever I run with the elcipse shadows... it does the same thing. I have shut those down, and keep them that way so I can navigate around with something that resembles fluid motion.

Thanks for any input....

Marshead

Marshead...

Are you using XP? If so I had the same exact problem with Celestia because I had the same card at one point...I eventually upgraded to a GeForce...But to solve your problem at the moment, when using the XP drivers for that card, celestia would run super slow...and well it was the only program that acted up...I eventually installed the factory drivers and it worked fine...but XP has issues with these drivers...so its up to you...

If your not an XP user then I would again say make sure...well in all cases...that you have the most recent drivers off the main ATI site...

marshead · Post #6by **marshead** » 28.03.2002, 20:43

OK,

I updated the drivers and it helped... some. It is still pretty sluggish when there are rings present, and the more of the rings you can see, the worse it gets.

Also, I'm using Win2K, so the XP problem, as far as I can tell, isn't bugging me.

Any further input that anyone can provide would be appreciated.

If there is anything I can do to test out ideas, I'd be more than happy.

Marshead

Post #7by **chris** » 16.04.2002, 07:43

I figured out what's causing the slowdown . . . It happens on an nVIDIA TNT as well. The problem is that I have to set a maximum mip map level in order to avoid getting 'axes' centered on the shadow at high mipmap levels. Unfortunately, not all cards support setting a maximum mipmap level. I worked around this by disabling mipmapping completely for graphics cards that don't support a maximum mipmap level. The TNT and Rage 128 cards report that they can support this feature, but they can only do it with software emulation! So every ring pixel is rendered through a very slow software path . . . and there's no way for Celestia to distinguish whether a particular OpenGL implementation will fall back to software or not if a maximum mipmap level is set. This has been such a headache . . . I think that the only way to make ring and eclipse shadows work reliably on every graphics card is to always disable mipmapping. I do still need to investigate the rendering quality ramifications before going with this solution.

--Chris

Post #8by **chris** » 16.04.2002, 08:34

Ok . . . I think that I have this completely fixed now. No more shadow axes, no more slowdowns, and the quality change is so slight that is unnoticeable unless you know exactly what to look for. In addition, I use texture border clamping on cards that support it (GeForce 3 and 4, probably Radeon too) so there's no quality loss there at all (in fact it's improved from before.)

--Chris

Sum0 · Post #9by **Sum0** » 16.04.2002, 16:37

I've had a problem with extreme slowdown and graphical corruption around Earth in the latest versions (as well as rings) - do you know if this will fix it? And when will it be available? Thanks...