Editing Z-buffering (section)

==Developments==

Even with small enough granularity, quality problems may arise when [[accuracy and precision|precision]] in the z-buffer's distance values are not spread evenly over distance. Nearer values are much more precise (and hence can display closer objects better) than values that are farther away. Generally, this is desirable, but sometimes it will cause artifacts to appear as objects become more distant. A variation on z-buffering which results in more evenly distributed precision is called '''w-buffering''' (see [[#W-buffer|below]]).

At the start of a new scene, the z-buffer must be cleared to a defined value, usually 1.0, because this value is the upper limit (on a scale of 0 to 1) of depth, meaning that no object is present at this point through the [[viewing frustum]].

The invention of the z-buffer concept is most often attributed to [[Edwin Catmull]], although Wolfgang Straßer described this idea in his 1974 Ph.D. thesis months before Catmull's invention.{{efn|See {{ill|Wolfgang Gilo{{!}}Wolfgang K. Giloi|de|Wolfgang Giloi}}, J. L. Encarnação, W. Straßer. "The Giloi’s School of Computer Graphics". Computer Graphics 35 4:12–16.}}

On more recent PC graphics cards (1999–2005), z-buffer management uses a significant chunk of the available memory [[Bandwidth (computing)|bandwidth]]. Various methods have been employed to reduce the performance cost of z-buffering, such as [[lossless compression]] (computer resources to compress/decompress are cheaper than bandwidth) and ultra-fast hardware z-clear that makes obsolete the "one frame positive, one frame negative" trick (skipping inter-frame clear altogether using signed numbers to cleverly check depths).

Some games, notably several games later in the [[Nintendo 64]]'s life cycle, decided to either minimize z-buffering (for example, rendering the background first without z-buffering and only using z-buffering for the foreground objects) or to omit it entirely, to reduce memory bandwidth requirements and memory requirements respectively. [[Super Smash Bros.]] and [[F-Zero X]] are two Nintendo 64 games that minimized z-buffering to increase [[Frame rate|framerates]]. Several [[Factor 5]] games also minimized or omitted z-buffering. On the Nintendo 64 z-Buffering can consume up to 4x as much bandwidth as opposed to not using z-buffering.<ref>{{Citation |title=How I implemented MegaTextures on real Nintendo 64 hardware |url=https://www.youtube.com/watch?v=Sf036fO-ZUk |access-date=2024-01-04 |language=en}}</ref>  

[[MechWarrior 2: 31st Century Combat|Mechwarrior 2]] on PC supported [[Screen resolution|resolutions]] up to 800x600<ref>{{Citation |title=3D Acceleration Comparison Ep11: Mechwarrior 2 - 3DFX / PowerVR / S3 Virge / ATI Rage / Matrox Mys |url=https://www.youtube.com/watch?v=wWzWdwj9NvU |access-date=2024-01-04 |language=en}}</ref> on the original 4 MB [[3dfx]] Voodoo due to not using z-buffering.