FSAA performance hit

Falz · 03-29-2004, 06:35 AM

The aquirum looks better with FSAA but I get an inordinately large performance hit at 4x.

With most games, I get about a 33% performance hit from 4xFSAA.

With the aquarium however, this is a whopping 75% performance hit! In other words, it's actually 4x slower (and interestingly, 2x lower for 2xFSAA).

Any explanation as to why this is?

I have an NVIDIA FX 5700.

feldon34 · 03-29-2004, 07:45 AM

All I know is that it has always been like this. I don't have a technical explanation however.

Jim Sachs · 03-29-2004, 08:15 AM

What resolution are the games running in? I haven't looked at any lately, but when I wrote the Aquarium ALL 3D programs used a 640x480 background. If you (roughly) double the resolution to 1024x768, you have 4 times as many pixels to antialias.

Falz · 03-30-2004, 12:57 AM

I run it at 1280x960x32 72 Hz with no AA, as that's as high as my monitor goes!

But I get the performance hit in any mode with AA. The newer GPUs have special features to minimise the AA performance hit, but for whatever reason they have no effect on the aquarium.

Falz · 03-30-2004, 01:02 AM

Oh by the way, this card is smart enough not to AA flat surfaces (like the background), it only AAs between polygons. I think it also doesn't AA textures with alpha blending.

Jim Sachs · 03-30-2004, 02:03 AM

The background is still polygons -- 12 of them. They are just facing forward and don't move. At 1024x768, they would be 1-for-1 ratio with the screen pixels, but any other resolution should trigger antialiasing.

I can see how low resolutions could still cause a significant performance hit, because all 1024x786 pixels of the background would have to be taken into account even to downsample to 640x480.

Is there as much of a slowdown when using 16-bit?

Falz · 04-01-2004, 12:57 PM

Well I'm normally using 1024x768 with FSAA so it's probably another factor. Same problems in 16 bit, yes. I'd never use 16 bit anyway as NVIDIA 16 bit dithering is horrible!

Could be that NVIDIA drivers are optimised for later versions of DirectX, and MA being a DX6 app, could have something to do with that.

Jim Sachs · 04-01-2004, 01:18 PM

In the past, nVidia dithering has always been fabulous on every card and monitor I have here. Absolutely no visible difference between 16 and 32-bit when viewing smooth gradations. But these new drivers which I installed last week do seem to show a little banding that I don't remember seeing before.

Falz · 04-04-2004, 06:52 AM

If memory serves NVIDIA always had a really lousy 16 bit quality, which is why they were the first to go to 32 bit. 3dfx had that "22 bit" post filter thing which made 16 bit look nearly as good as 32.

After using my Voodoo5 for ages, when I got a GeForce FX the dithering in 16 bit stuck out at me like a sore thumb. Obviously I'm only using 32 bit with it :-)

03-29-2004, 06:35 AM	#1
Falz Registered Join Date: Apr 2003 Location: Australia Posts: 118	FSAA performance hit The aquirum looks better with FSAA but I get an inordinately large performance hit at 4x. With most games, I get about a 33% performance hit from 4xFSAA. With the aquarium however, this is a whopping 75% performance hit! In other words, it's actually 4x slower (and interestingly, 2x lower for 2xFSAA). Any explanation as to why this is? I have an NVIDIA FX 5700.

03-29-2004, 07:45 AM	#2
feldon34 Forum Administrator Join Date: Dec 2000 Location: Rock Hill, SC Posts: 10,939	All I know is that it has always been like this. I don't have a technical explanation however. "Journalism is printing what someone else does not want printed. Everything else is public relations." - George Orwell "If voting changed anything, they'd make it illegal." - Emma Goldman

03-29-2004, 08:15 AM	#3
Jim Sachs Developer Join Date: Dec 2000 Location: Southern Oregon Posts: 9,791	What resolution are the games running in? I haven't looked at any lately, but when I wrote the Aquarium ALL 3D programs used a 640x480 background. If you (roughly) double the resolution to 1024x768, you have 4 times as many pixels to antialias. Jim Sachs Creator of SereneScreen Aquarium

03-30-2004, 02:03 AM	#6
Jim Sachs Developer Join Date: Dec 2000 Location: Southern Oregon Posts: 9,791	The background is still polygons -- 12 of them. They are just facing forward and don't move. At 1024x768, they would be 1-for-1 ratio with the screen pixels, but any other resolution should trigger antialiasing. I can see how low resolutions could still cause a significant performance hit, because all 1024x786 pixels of the background would have to be taken into account even to downsample to 640x480. Is there as much of a slowdown when using 16-bit? Jim Sachs Creator of SereneScreen Aquarium

04-01-2004, 01:18 PM	#8
Jim Sachs Developer Join Date: Dec 2000 Location: Southern Oregon Posts: 9,791	In the past, nVidia dithering has always been fabulous on every card and monitor I have here. Absolutely no visible difference between 16 and 32-bit when viewing smooth gradations. But these new drivers which I installed last week do seem to show a little banding that I don't remember seeing before. Jim Sachs Creator of SereneScreen Aquarium

03-30-2004, 12:57 AM	#4
Falz Registered Join Date: Apr 2003 Location: Australia Posts: 118	I run it at 1280x960x32 72 Hz with no AA, as that's as high as my monitor goes! But I get the performance hit in any mode with AA. The newer GPUs have special features to minimise the AA performance hit, but for whatever reason they have no effect on the aquarium.

03-30-2004, 01:02 AM	#5
Falz Registered Join Date: Apr 2003 Location: Australia Posts: 118	Oh by the way, this card is smart enough not to AA flat surfaces (like the background), it only AAs between polygons. I think it also doesn't AA textures with alpha blending.

04-01-2004, 12:57 PM	#7
Falz Registered Join Date: Apr 2003 Location: Australia Posts: 118	Well I'm normally using 1024x768 with FSAA so it's probably another factor. Same problems in 16 bit, yes. I'd never use 16 bit anyway as NVIDIA 16 bit dithering is horrible! Could be that NVIDIA drivers are optimised for later versions of DirectX, and MA being a DX6 app, could have something to do with that.

04-04-2004, 06:52 AM	#9
Falz Registered Join Date: Apr 2003 Location: Australia Posts: 118	If memory serves NVIDIA always had a really lousy 16 bit quality, which is why they were the first to go to 32 bit. 3dfx had that "22 bit" post filter thing which made 16 bit look nearly as good as 32. After using my Voodoo5 for ages, when I got a GeForce FX the dithering in 16 bit stuck out at me like a sore thumb. Obviously I'm only using 32 bit with it :-)