The following was posted By: William Thomas

It is quite possible that you are running at that high a resolution. The difference is that you are not using Z-buffering. (Neither Flight Sim 98 or MSCFS support z-buffering in Direct 3d for 3dfx.)

My voodoo I can support 600*800 without z-buffering but is restricted to 640*480 with z-buffering.

The reason you have been told that you can not go past 600*800 is because that is the highest you will go (without SLI) with z-buffering.

The Z-buffer in 3dfx is part of the frame buffer memory. In a voodoo 1 part 2MB is frame buffer, 2MB is texture (thus 4 MB) In a voodoo 2, 4 Meg is Frame buffer and either 4 or 8 meg is texture memory depending on whether it is a 8 or 12 meg card. The reason that performance was not that different between 8 and 12 meg voodoo 2 cards is because there are not that many games currently fill 4 megs of texture memory, therefore in the 12meg cards 4 megs was basically going unused. This will change as games get more complex and use multi-texturing more fully.

What is Z-buffering? The following definition from webopedia.internet.com is probably the easiest to understand

"it is an algorithm used to determine which objects or parts of objects are visible and which are hidden. With Z-buffering the graphics processor stores the z-axis value of each pixel in a special area of memory called the z-buffer. Different objects can have the same x and y coordinates but with different z coordinate values. The object with the lowest z coordinate value is in front of the other objects and therefore is the one that's displayed"

So, Z-buffering is what helps gives the sim the feeling of "depth". Not all cards support z-buffering so they use a technique called z-sorting. It desplays all objects serially starting with the objects furthest back. It does not require a z-buffer but it is slower AND DOES NOT RENDER INTERSECTING OBJECTS CORRECTLY. (did some one say fluffy clouds????)

So. Why is Pro-Pilot so much faster in 640*480 than FS98? You have your answer. Pro-Pilot enables the z-buffer on you're card and thereby renders faster, and can render the fluffy clouds. FS98 uses D3D and does not use z-buffering, it uses z-sorting, therefore you get higher resolutions because your frame buffer memory is not being used as a z-buffer, but you don't get the "right" perspective with the clouds. (2d clouds or 3d lego block clouds)

SO for all you "why is it 640*480?" crowd, I think I have answered sufficiently. Personally I would rather play at a lower resolution and have the z-buffer enabled, than play at higher and suffer with a lower image quality. (the only reason I run FS-98 in 600*800 is because their panels are illegible in 640*480. A problem, PP99 DOESN'T have.)

The following was posted By: Bruce Wilson

William has a very good post there. I'll add to it by discussing the math involved with 3D video.

First, memory is calculated in terms of 'bytes', which are 8 bits long. (8 bits was chosen because with 8 bits you can represent 256 things (2 to the eighth power), enough to do the entire keyboard, or enough to represent all the different commands the early CPUs could use.) So if we do some simple calculations of the number of pixels needed for each resolution, here is what we get:

640x480 = 307,000 pixels
800x600 = 480,000 pixels
1024x768 = 786,000 pixels

Since it tales 16 bits to represent enough colors to look good (5 red, 5 green and 6 blue), we need to double these numbers to see how much memory it takes to hold one screenful of information:

640x480 = 0.62 MBytes
800x600 = 0.96 MB
1024x768 = 1.58 MB

But 3D cards use two different areas to display the screen information, each called a buffer. One buffer holds the informaiton that is currently being displayed, while the other buffer, the back buffer, is being drawn (it takes a little time to draw all the information, so it's done in the background, where we can't see it). This means that we need to double the memory needed:

640x480 = 1.24 MB
800x600 = 1.92 MB
1024x768 = 3.15 MB

But like William said, some programs use an additional buffer, the z-buffer, to store depth information. The z-buffer is usually the same resolution as the frame buffer, so we add more memory:

640x480 = 1.9 MB
800x600 = 2.9 MB
1024x768 = 4.75 MB

So all you need to do is figure out how much memory your card has, and you can tell what the max resolution you can run. A Voodoo card has a 2 MB frame buffer and 2 MB texture memory, so it's maximum resolution is 800x600 with no z-buffer, 640x480 with. A Voodoo2 card has 4 MB frame buffer and either 4 or 8 MB texture memory, so the 4 MB will hold either 800x600 with a z-buffer, 1024x768 without.

Other cards use the Unified Memory Architecture, which means there is no definite frame buffer size; the program uses as much video memory as it needs, and leaves the rest to the texture memory. For example, if you use a Verite 2200 card that has only 4 MB of unified memory and you run FS98 at 1024x768, you see a big problem: some 3D objects lose their textures and become gray, or all the ground textures become very fuzzy. It means that you are out of texture memory and the program has to make some sacrifices. It will throw some textures out, and other will use a smaller, low-resoluiton form of the texture that uses less memory.

AGP cards are nice because they can use some of your system memory to store the texture information. Savage3D cards are nice because they can compress textures before sending them to the card, so they use less video memory.

Most game designers try to work within the 2MB/2MB limit of the Voodoo card (by far the most succesful gamers 3D card in history). Lately games are being designed with variable memory requirements; if the memory is there they use a different set of high-res textures, if not they use the standard set. They are rare, though, because that means a lot of development time just to appease they 32-MB card crowd.

Now, why does Dynamix use only 640x480? Sure, it's the only resoluiton Voodoo cards can use, but I suspect it's because of the panels. Having such great panels means that there is a lot of interaction porgrammed into the screen locations, and if you switch resolution not only do you need a whole new set of graphics, but you need to reprogram all the cursor positions. It's doable, but it takes time.

Myself, I'd love to see 800x600 (maybe higher if Banshee cards really take off). It just doesn't seem a priority there now. (ATC, roads, flight model probably are getting the attention).

If you have more questions, go to the FSbench site and read about it there.

1. From the Windows Desktop, right-click the mouse.
2. Select Properties from the menu.
3. Click the Settings tab.
4. Click the Advanced button.
5. Click the Glide Settings tab.
6. The default will be a Gamma Correction of 1.70.
7. Move the slider to the left to darken the display (if it appears washed-out).
8. Move the slider to the right to lighten the display (if the scenery is too dark).
9. Click on the OK button to close the Advanced window.
10. Click on the OK button to close the Display Properties window.