Z-Buffering

[ACM]

Can someone please point me to a website of a detailed explanation of what Z-buffering is. I know it's where the graphics card stores 3D information, but everything on the screen is in 2D. There is no such thing as a 3D pixel - it's just a lighted piece of the screen, and the graphics card tells the monitor how bright it should be.

Also when working out how much video RAM a resolution of 800x600 in 16 bit color mode will use with Z-buffering, why do they calculate it like this; 800x600 x 16 bit color x 16 bits for z-buffer - I mean there is still going to be only 16 bits used for every pixel so why do we times it by 16 twice?

[RenegadeKing]

"Z-buffering is an algorithm used in 3-D graphics to ensure that perspective works the same way in the virtual world as it does in the real one: a solid object in the foreground will block the view of one behind it. You've seen this illustrated in the real world when someone stands between you and the television screen. Z-buffering is a type of algorithm known as a Visual Surface Determination (VSD) algorithm.

Z-buffering works by testing pixel depth and comparing the current position (z coordinate) with stored data in a buffer (called a z-buffer) that holds information about each pixel's last postion. The pixel in the closer position to the viewer is the one that will be displayed, just as the person in front of the television is what the viewer sees rather than the screen.

Z-buffering is one of three VSD algorithms commonly used for this purpose. The other two, BSP trees and depth sorting, work with polygons and consequently are less effective for portrayal of movement and overlap. Since it works at the pixel level, z-buffering can be demanding in terms of memory and processing time. Nevertheless, its more complex and life-like simulation of real-world object dynamics ensures its continuing popularity as a 3-D graphics development tool."

- http://whatis.techtarget.com/definit...284005,00.html

[Demosthenes]

You ever play games like Kings Quest, Quest for Glory, Indiana Jones, Full Throttle or any kind of 2-d quest/adventure game?
Ever notice how you walk behind some object or in front of others, such as pillars or such?

That is z-buffering in action. You basically take the screen shot, and then color all the objects you want to be an "interactive" layer (for lack of better words) as a different color (256 colors with which to play). The rest (background) is black, meaning everything is painted on top of it. The z-buffering picture looks like a bad second grade coloring book picture of the scene, but it tells the computer what is above what. Search for z-buffering and I am sure you will see a picture of how to make one.

That is old knowledge. I have no idea what they use it for now in 3d engines. But, for the above purposes, it was a really slick means of getting the job done.

Respectfully,

Demosthenes