Unified shader model
Encyclopedia
Unified Shader Model term is used to describe two similar but separate concepts: Unified Shading Architecture and Unified Shader Model.
Model (known in OpenGL as simply "Unified Shader
Model", known in Direct3D 10 as "Shader Model 4.0"), uses a consistent instruction set across all shader types. All shader types have almost the same capabilities - they can read from textures, data buffers and perform the same set of arithmetic instructions.
However, the instruction set is not completely the same between different shader types - for example, only the pixel shader can read textures with implicit coordinate gradients; only the geometry shader can emit extra rendering primitives and so on.
Early shader models (such as Shader Model 1.x) used very different instruction sets for vertex and pixel shaders, with vertex shaders having much more flexible instruction set. Later shader models (such as Shader Model 2.x and 3.0) reduced the differences, approaching Unified Shader Model.
Hardware is not required to have Unified Shading Architecture to support Unified Shader Model, and vice versa. A Direct3D 10 level hardware can still have dedicated vertex, geometry and pixel processors (although because of very similar ISA, they would be quite similar on hardware level). A technologically earlier (e.g. Shader Model 3.0) hardware can also have unified architecture, as is the case with Xenos graphics chip in Xbox 360, for example.
Unified Shader Architecture allows more flexible use of the graphics rendering hardware. For example, in a situation with a heavy geometry workload the system could allocate most computing units to run vertex and geometry shaders. In cases with less vertex workload and heavy pixel load, more computing units could be allocated to run pixel shaders.
Graphics processors that have unified shading architecture include the Nvidia
GeForce 8 series
, Geforce 9 series, GeForce 200 Series
, GeForce 400 Series
and GeForce 500 Series
, ATI
Radeon HD 2000
, Radeon HD 3000, Radeon HD 4000
, Radeon HD 5000 series and Radeon HD 6000 series
, S3 Chrome 400
, Chrome 500, Intel GMA
X3000 series, Xbox 360's GPU and others.
Unified Shader Model
The Unified ShaderShader
In the field of computer graphics, a shader is a computer program that is used primarily to calculate rendering effects on graphics hardware with a high degree of flexibility...
Model (known in OpenGL as simply "Unified Shader
Shader
In the field of computer graphics, a shader is a computer program that is used primarily to calculate rendering effects on graphics hardware with a high degree of flexibility...
Model", known in Direct3D 10 as "Shader Model 4.0"), uses a consistent instruction set across all shader types. All shader types have almost the same capabilities - they can read from textures, data buffers and perform the same set of arithmetic instructions.
However, the instruction set is not completely the same between different shader types - for example, only the pixel shader can read textures with implicit coordinate gradients; only the geometry shader can emit extra rendering primitives and so on.
Early shader models (such as Shader Model 1.x) used very different instruction sets for vertex and pixel shaders, with vertex shaders having much more flexible instruction set. Later shader models (such as Shader Model 2.x and 3.0) reduced the differences, approaching Unified Shader Model.
Unified Shading Architecture
When graphics hardware supports Unified Shader Model, it can make sense to design its computational units so that any of them can run any type of shader. When computational units are "unified", that is called Unified Shading Architecture. Most often such hardware is composed of an array of computing units and a dynamic scheduling / load balancing unit that distributes shader work to the computing units.Hardware is not required to have Unified Shading Architecture to support Unified Shader Model, and vice versa. A Direct3D 10 level hardware can still have dedicated vertex, geometry and pixel processors (although because of very similar ISA, they would be quite similar on hardware level). A technologically earlier (e.g. Shader Model 3.0) hardware can also have unified architecture, as is the case with Xenos graphics chip in Xbox 360, for example.
Unified Shader Architecture allows more flexible use of the graphics rendering hardware. For example, in a situation with a heavy geometry workload the system could allocate most computing units to run vertex and geometry shaders. In cases with less vertex workload and heavy pixel load, more computing units could be allocated to run pixel shaders.
Graphics processors that have unified shading architecture include the Nvidia
NVIDIA
Nvidia is an American global technology company based in Santa Clara, California. Nvidia is best known for its graphics processors . Nvidia and chief rival AMD Graphics Techonologies have dominated the high performance GPU market, pushing other manufacturers to smaller, niche roles...
GeForce 8 series
GeForce 8 Series
The GeForce 8 Series, is the eighth generation of NVIDIA's GeForce line of graphics processing units. The third major GPU architecture developed at NVIDIA, the GeForce 8 represents the company's first unified shader architecture.-Naming:...
, Geforce 9 series, GeForce 200 Series
GeForce 200 Series
The GeForce 200 Series is the 10th generation of Nvidia's GeForce graphics processing units. The series also represents the continuation of the company's unified shader architecture introduced with the GeForce 8 Series and the GeForce 9 Series. Its primary competition came from ATI's Radeon HD 4000...
, GeForce 400 Series
GeForce 400 Series
The GeForce 400 Series is the 11th generation of Nvidia's GeForce graphics processing units. The series was originally slated for production in November 2009, but, after a number of delays, launched on March 26, 2010 with availability following in April 2010....
and GeForce 500 Series
GeForce 500 Series
The GeForce 500 Series is a family of graphics processing units developed by Nvidia, based on the refreshed Fermi architecture. Nvidia officially announced the GeForce 500 series on 9 November 2010 with the launch of the GeForce GTX 580.- Overview :...
, ATI
Ati
As a word, Ati may refer to:* Ati, a town in Chad* Ati, a Negrito ethnic group in the Philippines* Ati-Atihan Festival, an annual celebration held in the Philippines* Ati, a queen of the fabled Land of Punt in Africa...
Radeon HD 2000
Radeon R600
The graphics processing unit codenamed the Radeon R600 is the foundation of the Radeon HD 2000/3000 series and the FireGL 2007 series video cards developed by ATI Technologies...
, Radeon HD 3000, Radeon HD 4000
Radeon R700
The Radeon R700 is the engineering codename for a graphics processing unit series developed by Advanced Micro Devices under the ATI brand name. The foundation chip, codenamed RV770, was announced and demonstrated on June 16, 2008 as part of the FireStream 9250 and Cinema 2.0 initiative launch media...
, Radeon HD 5000 series and Radeon HD 6000 series
Northern Islands (GPU family)
The Northern Islands series is a family of GPUs developed by Advanced Micro Devices for its Radeon line, based on the 40 nm process.Starting with this family, the former ATI brand was officially discontinued in favor of making a correlation between the graphics products and the AMD branding for...
, S3 Chrome 400
S3 Graphics Chrome 400
-History:VIA planned the production of 2 new graphics chips, Chrome 440 and 430, by the end of 2007. The Chrome 460 will support DirectX 10 and adopts a 90 nm process, while the Chrome 430 will support DirectX 10.1 and adopts a 65nm process. The Chrome 400 series was codenamed 'Destination'...
, Chrome 500, Intel GMA
Intel GMA
The Intel Graphics Media Accelerator, or GMA, is a series of Intel integrated graphics processors built into various motherboard chipsets....
X3000 series, Xbox 360's GPU and others.