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Cg or C for Graphics is a High level shader language created by nVidia for programming vertex and pixel shaders. The High Level Shader Language is a shader language developed by Microsoft for use with DirectX, and is very similar to Cg. ...
NVIDIA Corporation (NASDAQ: NVDA) is a major supplier of graphics processors (graphics processing units, GPUs), graphics cards, and media and communications devices for PCs and game consoles such as the original Xbox and the new upcoming next generation Playstation 3. ...
Computer programming (often simply programming) is the craft of implementing one or more interrelated abstract algorithms using a particular programming language to produce a concrete computer program. ...
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Cg is based on the C programming language and although they share the same syntax, some features of C were modified and new data types were added to make Cg more suitable for programming graphics processing units. The C Programming Language, Brian Kernighan and Dennis Ritchie, the original edition that served for many years as an informal specification of the language The C programming language is a general-purpose, procedural, imperative computer programming language developed in the early 1970s by Dennis Ritchie for use on the UNIX...
It has been suggested that Video Display Processor be merged into this article or section. ...
Background
As a result of technical advancements in graphics cards, some areas of 3D graphics programming have become quite complex. To simplify the process, new features were added to graphics cards, including the ability to modify their rendering pipelines using vertex and pixel shaders.
In the beginning, vertex and pixel shaders were programmed at a very low level with only the assembly language of the graphics processing unit. Although using the assembly language gave the programmer complete control over code and flexibility, it was fairly hard to use. A portable, higher level language for programming the GPU was needed, so Cg was created to overcome these problems and make shader development easier.
Some of the benefits of using Cg over assembly are:
- High level code is easier to learn, program, read, and understand than assembly code.
- Cg code is portable to a wide range of hardware and platforms, unlike assembly code, which usually depends on hardware and the platforms it's written for.
- The Cg compiler can optimize code and do lower level tasks automatically, which are hard to do and error prone in assembly.
Details
Data types Cg has six basic data types, some of them are the same as in C, others are especially added for GPU programming, these types are: - float - a 32bit floating point number
- half - a 16bit floating point number
- int - a 32bit integer
- fixed - a 12bit fixed point number
- bool - a boolean variable
- sampler* - represents a texture object
Cg also features vector and matrix data types that are based on the basic data types, such as float3, float4x4, such data types are quite common when dealing with 3D graphics programming, Cg also has struct and array data types, which work in a similar way to C equivalents.
Operators Cg supports a wide range of operators, including the common arithmetic operators from C, the equivalent arithmetic operators for vector and matrix data types, and the common logical operators. In logical calculus, logical operators or logical connectors serve to connect statements into more complicated compound statements. ...
Functions and control structures Cg shares the basic control structures with C, like if/else, while, and for. It also has a similar way of defining functions.
The standard Cg library As in C, Cg features a set of functions for common tasks in GPU programming. Some of the functions have equivalents in C, like the mathematical functions abs and sin, while others are specialized in GPU programming tasks, like the texture mapping functions tex1D and tex2D.
The Cg runtime library Cg programs are merely vertex and pixel shaders, and they need supporting programs that handle the rest of the rendering process, Cg can be used with two APIs, OpenGL or DirectX, each has its own set of Cg functions to communicate with the Cg program, like setting the current Cg shader, passing parameters, and such tasks. API may refer to: In computing, application programming interface In petroleum industry, American Petroleum Institute In education, Academic Performance Index This page concerning a three-letter acronym or abbreviation is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...
OpenGL official logo OpenGL (Open Graphics Library) is a standard specification defining a cross-language cross-platform API for writing applications that produce 3D computer graphics (and 2D computer graphics as well). ...
DirectX is a collection of proprietory APIs for handling tasks related to game programming and limited to the Microsoft Windows operating system. ...
A sample Cg vertex shader // input vertex struct VertIn { float4 pos : POSITION; float4 color : COLOR0; }; // output vertex struct VertOut { float4 pos : POSITION; float4 color : COLOR0; }; // vertex shader main entry VertOut main(VertIn IN, uniform float4x4 modelViewProj) { VertOut OUT; OUT.pos = mul(modelViewProj, IN.pos); // calculate output coords OUT.color = IN.color; // copy input color to output OUT.color.z = 1.0f; // blue component of color = 1.0f return OUT; }
Applications and games that use Cg Far Cry is a first-person shooter computer game developed by Crytek Studios and published by Ubisoft on March 23, 2004. ...
The PlayStation 3 (PS3) will be Sonys seventh generation era video game console in the PlayStation series. ...
This article is about a program that is hosted by SourceForge. ...
This article is about a program that is hosted by SourceForge. ...
Further reading - Randima Fernando, Mark J. Kilgard, The Cg Tutorial: The Definitive Guide to Programmable Real-Time Graphics, Addison-Wesley Professional, ISBN 0-32119-496-9
- Randima Fernando, GPU Gems: Programming Techniques, Tips, and Tricks for Real-Time Graphics, Addison-Wesley Professional, ISBN 0-32122-832-4
- William R. Mark, R. Steven Glanville, Kurt Akeley, Mark J. Kilgard, Cg: A System for Programming Graphics Hardware in a C-like Language, Proceedings of SIGGRAPH 2003.
- Mark J. Kilgard, Cg in Two Pages, 2003.
Mark J. Kilgard is a graphics software engineer. ...
Kurt Akeley is a computer graphics engineer. ...
See also HTML and JavaScript in an IDE that uses color coding to highlight various keywords and help the developer see the function of each piece of code. ...
Computer graphics (CG) is the field of visual computing, where one utilizes computers both to generate visual images synthetically and to integrate or alter visual and spatial information sampled from the real world. ...
Vertex and pixel (or fragment) shaders are shaders that run on a graphics card, executed once for every vertex or pixel in a specified 3D mesh. ...
The High Level Shader Language is a shader language developed by Microsoft for use with DirectX, and is very similar to Cg. ...
A shader is a program used in 3D computer graphics to determine the final surface properties of an object or image. ...
OpenGL official logo OpenGL (Open Graphics Library) is a standard specification defining a cross-language cross-platform API for writing applications that produce 3D computer graphics (and 2D computer graphics as well). ...
DirectX is a collection of proprietory APIs for handling tasks related to game programming and limited to the Microsoft Windows operating system. ...
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