High-Level Shading Language

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A scene containing several different 2D HLSL shaders. The statue is distorted purely physically, while the inner door texture is physically distorted based on color intensity. The square in back is transformed and rotated via a shader, and the water reflection and partial transparency at the bottom have been added by a final shader acting on the entire scene.

The High-Level Shader Language[1] or High-Level Shading Language[2] (HLSL) is a proprietary shading language developed by Microsoft for the Direct3D 9 API to augment the shader assembly language, and went on to become the required shading language for the unified shader model of Direct3D 10 and higher.

HLSL is analogous to the GLSL shading language used with the OpenGL standard. It is very similar to the Nvidia Cg shading language, as it was developed alongside it.[3] HLSL shaders can enable profound speed and detail increases as well as many special effects in both 2d and 3d computer graphics.

HLSL programs come in five forms: pixel shaders (fragment in GLSL), vertex shaders, geometry shaders, compute shaders and tessellation shaders (Hull and Domain 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 10/11/12 interface and Direct3D 10/11/12 hardware may also specify a geometry shader. This shader takes as its input some vertices of a primitive (triangle/line/point) and uses this data to generate/degenerate (or tessellate) additional primitives or to change the type of primitives, which are each then sent to the rasterizer.

D3D11.3 and D3D12 introduced Shader Model 5.1[4] and later 6.0.[5]

Shader model comparison[edit]

GPUs listed are the hardware that first supported the given specifications. Manufacturers generally support all lower shader models through drivers. Note that games may claim to require a certain DirectX version, but don't necessarily require a GPU confirming to the full specification of that version, as developers can use a higher DirectX API version to target lower-Direct3D-spec hardware; for instance DirectX 9 exposes features of DirectX7-level hardware that DirectX7 did not, targeting their fixed-function T&L pipeline.

Pixel shader comparison[edit]

Pixel shader version 1.0 to 1.3[6] 1.4[6] 2.0[6][7] 2.0a[6][7][8] 2.0b[6][7][9] 3.0[6][10] 4.0[11]
Dependent texture limit 4 6 8 Unlimited 8 Unlimited Unlimited
Texture instruction limit 4 6*2 32 Unlimited Unlimited Unlimited Unlimited
Position register No No No No No Yes Yes
Instruction slots 8+4 8+4 32 + 64 512 512 ≥ 512 ≥ 65536
Executed instructions 8+4 6*2+8*2 32 + 64 512 512 65536 Unlimited
Texture indirections 4 4 4 Unlimited 4 Unlimited Unlimited
Interpolated registers 2 + 8 2 + 8 2 + 8 2 + 8 2 + 8 10 32
Instruction predication No No No Yes No Yes No
Index input registers No No No No No Yes Yes
Temp registers 2 6 12 to 32 22 32 32 4096
Constant registers 8 8 32 32 32 224 16×4096
Arbitrary swizzling No No No Yes No Yes Yes
Gradient instructions No No No Yes No Yes Yes
Loop count register No No No No No Yes Yes
Face register (2-sided lighting) No No No No Yes Yes Yes
Dynamic flow control No No No No No 24 Yes
Bitwise Operators No No No No No No Yes
Native Integers No No No No No No Yes

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

Vertex shader comparison[edit]

Vertex shader version VS 1.1[14] VS 2.0[7][14][15] VS 2.0a[7][14][15] VS 3.0[10][14] VS 4.0[11]
VS 4.1[16]
VS 5.0[13]
# of instruction slots 128 256 256 ≥ 512 4096
Max # of instructions executed 128 1024 65536 65536 65536
Instruction predication No No Yes Yes Yes
Temp registers 12 12 16 32 4096
# constant registers ≥ 96 ≥ 256 256 ≥ 256 16×4096
Static flow control No Yes Yes Yes Yes
Dynamic flow control No No Yes Yes Yes
Dynamic flow control depth No No 24 24 Yes
Vertex texture fetch No No No Yes Yes
# of texture samplers N/A N/A N/A 4 128
Geometry instancing support No No No Yes Yes
Bitwise operators No No No No Yes
Native integers No No No No Yes

See also[edit]


  1. ^ "Writing HLSL Shaders in Direct3D 9 (Windows)". msdn.microsoft.com. 
  2. ^ "HLSL". MSDN. Microsoft. Retrieved 5 January 2015. 
  3. ^ "Fusion Industries :: Cg and HLSL FAQ ::". 24 August 2012. 
  4. ^ "Shader Model 5.1 Objects (Windows)". msdn.microsoft.com. 
  5. ^ "HLSL Shader Model 6.0 (Windows)". msdn.microsoft.com. 
  6. ^ a b c d e f "Pixel Shader Differences". msdn.microsoft.com. 2011-02-08. 
  7. ^ a b c d e Peeper, Craig (2004-03-15). "Microsoft DirectX High Level Shader Language (HLSL)" (PPT). microsoft.com. pp. 5–8, 24–25. 
  8. ^ Shimpi, Anand Lal. "NVIDIA Introduces GeForce FX (NV30)". 
  9. ^ Wilson, Derek. "ATI Radeon X800 Pro and XT Platinum Edition: R420 Arrives". 
  10. ^ a b Shader Model 3.0, Ashu Rege, NVIDIA Developer Technology Group, 2004.
  11. ^ a b The Direct3D 10 System, David Blythe, Microsoft Corporation, 2006.
  12. ^ "Registers - ps_4_1 (Windows)". msdn.microsoft.com. 
  13. ^ a b "Registers - ps_5_0 (Windows)". msdn.microsoft.com. 
  14. ^ a b c d "Vertex Shader Differences". msdn.microsoft.com. 2011-02-08. 
  15. ^ a b Shimpi, Anand Lal. "NVIDIA Introduces GeForce FX (NV30)". 
  16. ^ "Registers - vs_4_1 (Windows)". msdn.microsoft.com. 

External links[edit]