[Mikeman]

I'm trying to figure out what one is and if my mac has one

[AquaSeahorse]

Um I'd assume its something that acclerates 3D graphics Sorry I really have no idea about them

[wgscott]

here is a description if you can wade through the marketing hype:

http://store.apple.com/1-800-MY-APPL...1.7.0.5.2.13.0

[MarkS]

Whay model is your Mac? I can probably tell you if yours does if I know the model.

As to your other question...

A 3D-Accelerator does just that, it accelerates 3D graphics. I'll explain, but I am assuming that you have at least a little understanding of trig, calculus, algrabra I & II, etc.

When you play all of your favorite 3D games, what is going on behind the scenes is very complex. Every object on screen is composed or vertices, textures and lighting info.

A vertex is composed of 3 numbers representing the x, y and z coords of the vertex in an arbritary space.

Let's say that object 1 has one vertex. It is arranged like this:
x = 0
y = 1.24587
z = 25.254

To simplify this discussion, here's a quick test: quickly, in your head, multiply 5 x 5. Now do 1.24587 x 25.254. The computer, while faster, has just as much trouble.

Now understand that your game has thousands or tens of thousands of vertices per frame and the computer must add, subtract multiply and divide values by EVERY vertex. It must then light the polygon, texture it and display it. All the while handling every other task that the computer normally does.

That is, in a VERY simplified discussion, what a 3D card does. It simply removes all of the 3D math, lighting, texturing and writing to the display from the computer's main CPU and does it with an array of very fast processors. This allows your game to run in real time. Without the 3D card, you would move your character and wait a minute or two for the screen to show the change.

I do a lot of 3D programming, or rather used to (got boring) and could go on for hours. Books bigger than the yellow pages have been written just on this subject.

Anyway, more info than you wanted to know...

Mark

[Mikeman]

its one of the first imacs released,


I really am not into computers, other than being able to go on the internet, typing fast, and playing games, althought the proccesor is a powerpc g3.....atleast thats what is says in the system profiler.
thanks mark

[wgscott]

A very simple example is a program that displays a molecule. Each atom has a set of coordinates x,y,z, and these make up a 3-dimensional shape. The screen obviously is 2-D, but programs that allow you to rotate the image of the molecule by moving the mouse or dialbox give the illusion of 3-D through rotation. Any arbitrary rotation can be represented as a 3x3 matrix, and when you rotate your molecule say 5 degrees along the z axis, you apply a transformation matrix to (x,y,z) and get new values (x',y',z'=z). So application of this operation gives you new x and y coordinates. You don't have to rotate about the z axis, any arbitrary rotation changes the old coordinates into the new. In order to get a nice smooth real-time response, your computer has to update the image in small fraction-of-a-second intervals. In each of these intervals it has to perform the above calculation FOR EVERY POINT or pixel of the image. Hence it has to do a huge number of these numerical calculations, quickly, and display the new results on the screen essentially instantaneously.

SGI traditionally has made the best hardware for doing so, and also you can get stereo view glasses, dial boxes, etc. that permit you to obtain the maximum 3-D effects.

Basically the better your graphics card, the more realistic your game or simulation or whatever, both in terms of image quality and delay time for response to a rotation, etc.