Question about "shimmer"

[numbr007]

I have a rather silly question about the "shimmer" option. In both MA and GA, I can see absolutely no difference between when I have the "shimmer" option switched off or on. What exactly does "shimmer" do, and why can't I see it? I'm running a G4 867MHz with nVidia GForce 3 card.

Thanks!

[JimO'Connor]

You can see shimmer, it is just very subtle. Once you notice it you'll never want it off (probably).

Shimmer is the recalculation of the angle between the fish's surface and the light source. So with shimmer, the shadows on the fish change as different parts of the fish change their relationship to the light source. Without shimmer the shadows on the fish are calculated once and remain the same for the execution of the program. Notice how when the long fins of Cali face down they get darker, but when they face up they get lighter? That is shimmer.

At reasonable framerates the medium shimmer setting is as realistic as the high shimmer setting.

[feldon34]

Us Windows users call it "Calculate Normals".

[johnblommers]

In 3D imagery, if you want to avoid the plastic look, you apply a bump map to the surface as well as a texture. The texture provides the pretty colors. The bump map bends the surface normals. Shine a light at an angle and the bump map's effect is that you see a bump in the surface. The bump map allows you to create the appearance of bumpy surfaces without actually modeling the bumps in the surface mesh model.

It's a general concept not only in Wintel Land.

If you ever played Halo, turn on your gun's light and shine in at an angle to a bunker's surface, and you will see the effect of bump mapping.

Sooooooooooo, this is my sneaky way of asking if Goldfish Aquarium is going to get bump mapping to make the rocks and plants look more realistic. The fish look very nice already but a bump map there would REALLY add to the realism.

Oho so now I am on a roll. Speaking of realism. I can see jagged lines on the larger fish bodies against the clear watery background - is it possible that Goldfish Aquarium is not anit-aliased? I can enable this feature for the application version using the ATI preferences pane, but I am not convinced this will work for the screen saver version.

[feldon34]

Goldfish Aquarium needs specular maps before they even dream of bump maps.

[JimO'Connor]

Yes, surface normals is the proper name. When we were making the control for version 1 of MA we came up with "shimmer" as being more descriptive to nontechnical people.

Eric and I discussed bump mapping. It won't be a version 1 feature. It might be a feature beyond 1, but no promises for when.

There does appear to be a problem with the mipmapping which shows up with some of the fish's dorsal fins. That is on my list to investigate.

[johnblommers]

So I experimented with the FSAA feature of the ATI perferences pane to study the effects on the GA application running at 1024x768 on a millions of color display.

At 1024x768 resolution with 3 bytes per pixel is about 3 meg of VRAM just for the frame buffer that holds the final image for display.

Now my ATI 9600 Pro is dual headed so the 64Meg VRAM is allocated evenly across two monitors. I monitor the VRAM usage while running the GA application and almost locked up my machine going to 6x anti-alliasing. Even at 4x I could not get a stable VRAM indicaton.

If I understand how this works, 2x FSAA means each pixel is evaluated across a 2x2=4 bit sample, so it takes 4 times as much VRAM? That would eat up 12 meg of VRAM in my case.

So 4x FSAA menas 4x4=16 times as much VRAM and 6x FSAA means 6x6=36 times as much VRAM. If this is true, no wonder my system almost locked up at 6x FSAA! There's not enough VRAM to support that!

So now I realize that FSAA on GA is a practical option only for those with one monitor and LOTS of VRAM, like 128Meg or 258Meg.

Who knew?

[JimO'Connor]

Yes, and I checked and the mip mapping is on for the goldfish, and I walked through the code as it executed to be sure nothing went askew.