High-level shader language

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The High-level shader language or High-level shading language (HLSL) is a proprietary shading language developed by Microsoft for use with the Microsoft Direct3D API. It is analogous to the GLSL shading language used with the OpenGL standard. It is the same as the Nvidia Cg shading language, as it was developed alongside it.[1]

HLSL programs come in three forms: vertex shaders, geometry shaders, and pixel (or fragment) shaders. A vertex shader is executed for each vertex that is submitted by the application, and is primarily responsible for transforming the vertex from object space to view space, generating texture coordinates, and calculating lighting coefficients such as the vertex's tangent, binormal and normal vectors. When a group of vertices (normally 3, to form a triangle) come through the vertex shader, their output position is interpolated to form pixels within its area; this process is known as rasterisation. Each of these pixels comes through the pixel shader, whereby the resultant screen colour is calculated.

Optionally, an application using a Direct3D 10/11 interface and Direct3D 10/11 hardware may also specify a geometry shader. This shader takes as its input the three vertices of a triangle and uses this data to generate (or tessellate) additional triangles, which are each then sent to the rasterizer.

Shader model comparison

Pixel shader comparison

Pixel shader version 1.0 to 1.3[2] 1.4[2] 2.0[2][3] 2.0a[2][3] 2.0b[2][3] 3.0[2][4] 4.0[5] 4.1[6] 5.0[7]
Dependent texture limit 4 6 8 Unlimited 8 Unlimited Unlimited Unlimited Unlimited
Texture instruction limit 4 6*2 32 Unlimited Unlimited Unlimited Unlimited Unlimited Unlimited
Position register No No No No No Yes Yes Yes Yes
Instruction slots 8+4 8+4 32 + 64 512 512 ≥ 512 ≥ 65536 ≥ 65536 ≥ 65536
Executed instructions 8+4 6*2+8*2 32 + 64 512 512 65536 Unlimited Unlimited Unlimited
Texture indirections 4 4 4 Unlimited 4 Unlimited Unlimited Unlimited Unlimited
Interpolated registers 2 + 8 2 + 8 2 + 8 2 + 8 2 + 8 10 32 32 32
Instruction predication No No No Yes No Yes No No No
Index input registers No No No No No Yes Yes Yes Yes
Temp registers 2 6 12 to 32 22 32 32 4096 4096 4096
Constant registers 8 8 32 32 32 224 16x4096 16x4096 16x4096
Arbitrary swizzling No No No Yes No Yes Yes Yes Yes
Gradient instructions No No No Yes No Yes Yes Yes Yes
Loop count register No No No No No Yes Yes Yes Yes
Face register (2-sided lighting) No No No No No Yes Yes Yes Yes
Dynamic flow control No No No No No 24 Yes Yes Yes
Bitwise Operators No No No No No No Yes Yes Yes
Native Integers No No No No No No Yes Yes Yes
  • PS 2.0 = DirectX 9.0 original Shader Model 2 specification.
  • PS 2.0a = NVIDIA GeForce FX-optimized model.
  • PS 2.0b = ATI Radeon X700, X800, X850 shader model, DirectX 9.0b.
  • PS 3.0 = Shader Model 3.0.
  • PS 4.0 = Shader Model 4.0.
  • PS 4.1 = Shader Model 4.1.
  • PS 5.0 = Shader Model 5.0.

"32 + 64" for Executed Instructions means "32 texture instructions and 64 arithmetic instructions."

Vertex shader comparison

Vertex shader version VS 1.1[8] VS 2.0[3][8] VS 2.0a[3][8] VS 3.0[4][8] VS 4.0[5] VS 4.1[9] VS 5.0[7]
# of instruction slots 128 256 256 ≥ 512 4096 4096 4096
Max # of instructions executed Unknown 65536 65536 65536 65536 65536 65536
Instruction predication No No Yes Yes Yes Yes Yes
Temp registers 12 12 13 32 4096 4096 4096
# constant registers ≥ 96 ≥ 256 ≥ 256 ≥ 256 16x4096 16x4096 16x4096
Static flow control ??? Yes Yes Yes Yes Yes Yes
Dynamic flow control No No Yes Yes Yes Yes Yes
Dynamic flow control depth No No 24 24 Yes Yes Yes
Vertex texture fetch No No No Yes Yes Yes Yes
# of texture samplers N/A N/A N/A 4 128 128 128
Geometry instancing support No No No Yes Yes Yes Yes
Bitwise operators No No No No Yes Yes Yes
Native integers No No No No Yes Yes Yes
  • VS 2.0 = DirectX 9.0 original Shader Model specification.
  • VS 2.0a = NVIDIA GeForce FX-optimized model.
  • VS 3.0 = Shader Model 3.0.
    • Note that ATI X1000 series cards (e.g. X1900) does not support Vertex Texture Fetch, hence it does not fully comply with the VS 3.0 model. Instead, they offer a feature called "Render to Vertex Buffer (R2VB)" that provides functionality that is a superset of Vertex Texture Fetch.[citation needed]
  • VS 4.0 = Shader Model 4.0.
  • VS 4.1 = Shader Model 4.1.
  • VS 5.0 = Shader Model 5.0.

See also

  • GLSL

Footnotes

  1. ↑ Fusion Industries :: Cg and HLSL FAQ ::
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 "Pixel Shader Differences". msdn.microsoft.com. 2011-02-08. 
  3. ↑ 3.0 3.1 3.2 3.3 3.4 Peeper, Craig (2004-03-15). "Microsoft DirectX High Level Shader Language (HLSL)" (PPT). microsoft.com. pp. 5–8, 24–25. 
  4. ↑ 4.0 4.1 Shader Model 3.0, Ashu Rege, NVIDIA Developer Technology Group, 2004.
  5. ↑ 5.0 5.1 The Direct3D 10 System, David Blythe, Microsoft Corporation, 2006.
  6. ↑ http://msdn.microsoft.com/en-us/library/windows/desktop/ff471379(v=vs.85).aspx
  7. ↑ 7.0 7.1 http://msdn.microsoft.com/en-us/library/windows/desktop/hh447212(v=vs.85).aspx
  8. ↑ 8.0 8.1 8.2 8.3 "Vertex Shader Differences". msdn.microsoft.com. 2011-02-08. 
  9. ↑ http://msdn.microsoft.com/en-us/library/windows/desktop/ff471381(v=vs.85).aspx

External links

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