Geometry pipelines: Difference between revisions

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{{Citations missingRefimprove|date=April 2009}}

Geometric manipulation of modelingmodelling 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 Geometrygeometry Pipelinespipelines 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 news journal

| last = Clark

| first = James

| title = Special Feature A VLSI Geometry Processor For Graphics

| pages = 59–68

| magazinejournal = Computer

| date = July 1980

| volume = 13

| url = http://www.computer.org/portal/web/csdl/doi/10.1109/MC.1980.1653711

| issue = 7

}}</ref><ref>{{Cite conference

| doi = 10.1109/MC.1980.1653711

| first = James

| lasts2cid = Clark2428227

}}</ref><ref>{{Cite conference

| title = The Geometry Engine: A VLSI Geometry System for Graphics

|first = James

| booktitle = Proceedings of the 9th annual conference on Computer graphics and interactive techniques

|last | pages = 127-133Clark

|title | title = The Geometry Engine: A VLSI Geometry System for Graphics

| date = July 1982

|book-title | booktitle = Proceedings of the 9th annual conference on Computer graphics and interactive techniques

| url = http://accad.osu.edu/~waynec/history/PDFs/geometry-engine.pdf

|pages = 127–133

|date | 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 [[patch]]repair [[surface normal]]s, and then to perform the [[computer graphics lighting|lighting]] and [[shading]] computations used in their subsequent rendering.

[[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 [[rendering]] pipeline. Geometric computations may also be applied to transform polygon or [[patch]] [[surface normal]]s, and then to perform the [[lighting]] and [[shading]] computations used in their subsequent rendering.

==History==

Hardware implementations of the geometry pipeline were introduced in the early [[Evans & Sutherland]] [[Picture System]], but perhaps received broader recognition when later applied in the broad range of graphics systems products introduced by [[Silicon Graphics]] (SGI). Initially the SGI geometry hardware performed simple [[model space]] to [[screen space]] [[viewing transformation]]s with all the lighting and shading handled by a separate hardware implementation stage, but. inIn later, much higher performance applications, such as the [[RealityEngine]], they began to be applied to perform part of the rendering support as well.

More recently, perhaps dating from the late 1990s, the hardware support required to perform the manipulation and rendering of quite complex scenes has become accessible to the consumer market.

Companies such as [[NVIDIANvidia]] and [[AMD Graphics]] (formerly [[ATI Technologies|ATI]]) are two current leading representatives of hardware vendors in this space. The [[GeForce]] line of [[graphics card]]s from NVIDIANvidia was the first to support full [[OpenGL]] and [[Direct3D ]] hardware geometry processing in the consumer PC market, while some earlier products such as Rendition Verite incorporated hardware geometry processing through proprietary programming interfaces. On the whole, earlier graphics accelerators by [[3Dfx]], [[Matrox]] and others relied on the [[Central processing unit|CPU]] for geometry processing.

This subject matter is part of the technical foundation for modern computer graphics, and is a comprehensive topic taught at both the undergraduate and graduate levels as part of a [[computer science]] education.

== See also ==

* [[Vertex pipeline]]

* [[Graphics pipeline]] (include [[Pixel pipeline]])

* [[Rasterisation]]

* [[Open Graphics Project]]

==References==

{{Reflist}}

{{Graphics Processing Unit}}

[[Category:3D computer graphics]]

[[Category:3D computer graphics]]

[[ja:ジオメトリエンジン]]