Editing Z-buffering (section)

==Usage==

=== Occlusion ===
Determining what should be displayed on the screen and what should be ommited is a multi-step process utilising various [[Hidden-surface determination|techniques]]. Using a z-buffer is the final step in this process.

Each time an object is rendered into the [[framebuffer]] the z-buffer is used to compare the z-values of the fragments with the z-value already in the z-buffer (i.e., check what is closer), if the new z-value is closer than the old value, the fragment is written into the framebuffer and this new closer value is written into the z-buffer. If the z-value is further away than the value in the z-buffer, the fragment is discarded. This is repeated for all objects and surfaces in the scene (often in [[Parallel computing|parallel]]). In the end, the z-buffer will allow correct reproduction of the usual [[depth perception]]: a close object hides one further away. This is called '''z-culling'''.

The [[Granularity (parallel computing)|granularity]] of a z-buffer has a great influence on the scene quality: the traditional [[16-bit computing|16-bit]] z-buffer can result in [[artifact (observational)|artifacts]] (called "[[z-fighting]]" or '''stitching''') when two objects are very close to each other. A more modern [[24-bit computing|24-bit]] or [[32-bit computing|32-bit]] z-buffer behaves much better, although the problem cannot be eliminated without additional algorithms. An [[8-bit computing|8-bit]] z-buffer is almost never used since it has too little precision.

=== Shadow mapping ===
Z-buffer data obtained from rendering a surface from a light's point-of-view permits the creation of shadows by the [[shadow mapping]] technique.<ref>{{Cite book |last1=Akenine-Möller |first1=Tomas |url=https://books.google.com/books?id=0g1mDwAAQBAJ&dq=%22shadow+mapping%22+%22z-buffer%22&pg=PA234 |title=Real-Time Rendering, Fourth Edition |last2=Haines |first2=Eric |last3=Hoffman |first3=Naty |date=2018-08-06 |publisher=CRC Press |isbn=978-1-351-81615-1 |language=en}}</ref>