Editing Geometry pipelines (section)

{{Refimprove|date=April 2009}}
Geometric manipulation of modelling primitives, such as that performed by a '''geometry pipeline''', is the first stage in [[computer graphics]] systems which perform image generation based on geometric models. While geometry pipelines were originally implemented in software, they have become highly amenable to hardware implementation, particularly since the advent of [[very-large-scale integration]] (VLSI) in the early 1980s.  A device called the '''Geometry Engine''' developed by [[James H. Clark|Jim Clark]] and [[Marc Hannah]] at [[Stanford University]] in about 1981 was the watershed for what has since become an increasingly commoditized function in contemporary image-synthetic [[raster graphics|raster display]] systems.<ref>{{Cite journal
  | last = Clark
  | first = James
  | title = Special Feature A VLSI Geometry Processor For Graphics
  | pages = 59–68
  | journal = Computer
  | date = July 1980
  | volume = 13
 | issue = 7
 | doi = 10.1109/MC.1980.1653711
 | s2cid = 2428227
 }}</ref><ref>{{Cite conference
 |first       = James
 |last        = Clark
 |title       = The Geometry Engine: A VLSI Geometry System for Graphics
 |book-title   = Proceedings of the 9th annual conference on Computer graphics and interactive techniques
 |pages       = 127–133
 |date        = July 1982
 |url=https://dl.acm.org/doi/pdf/10.1145/965145.801272 |citeseerx=10.1.1.359.8519 |doi=10.1145/965145.801272
}}
</ref>

[[Geometric transformation]]s are applied to the vertices of [[polygon]]s, or other geometric objects used as [[geometric primitive|modelling primitive]]s, as part of the first stage in a classical geometry-based graphic image [[Artistic rendering|rendering]] pipeline.  Geometric computations may also be applied to transform polygon or repair [[surface normal]]s, and then to perform the [[computer graphics lighting|lighting]] and [[shading]] computations used in their subsequent rendering.