High Level Shader Language

The High Level Shader Language ( HLSL ) is a shader language developed by Microsoft for use with Direct3D, and is very similar to Cg.

HLSL allows writing complex graphical computations to be done on the graphics card quickly and efficiently, thus allowing complex effects while also decreasing the chance of programming errors compared to assembly shader programming.

= Shader Model Comparison =

Pixel Shader Comparison

	PS_2_0	PS_2_a	PS_2_b	PS_3_0
Dependent texture limit	4	No Limit	4	No Limit
Texture instruction limit	32	Unlimited	Unlimited	Unlimited
Position register	No	No	No	Yes
Instruction slots	32 + 64	512	512	≥ 512
Executed instructions	32 + 64	512	512	≥65535
Interpolated registers	2 + 8	2 + 8	2 + 8	10
Instruction predication	No	Yes	No	Yes
Index input registers	No	No	No	Yes
Temp registers	12	22	32	32
Constant registers	32	32	32	224
Arbitrary swizzling	No	Yes	No	Yes
Gradient instructions	No	Yes	No	Yes
Loop count register	No	No	No	Yes
Face register (2-sided lighting)	No	No	No	Yes
Dynamic flow control	No	No	No	24

PS_2_0 = DirectX 9.0 original Shader Model 2 specification.
PS_2_a = NVIDIA GeForce FX-optimized model.
PS_2_b = ATI Radeon X700, X800, X850 shader model, DirectX 9.0b.
PS_3_0 = Shader Model 3.

Vertex Shader Comparison

	VS_2_0	VS_2_a	VS_3_0
# of instruction slots	256	256	>=512
Max # of instructions executed	65535	65535	>=65535
Instruction Predication	No	Yes	Yes
Temp Registers	12	13	32
# constant registers	>=256	>=256	>=256
Static Flow Control	Yes	Yes	Yes
Dynamic Flow Control	No	Yes	Yes
Dynamic Flow Control Depth	No	24	24
Vertex Texture Fetch	No	No	Yes
# of texture samplers	No	No	4
Geometry Instancing Support	No	No	Yes

VS_2_0 = DirectX 9.0 original Shader Model 2 specification.
VS_2_a = NVIDIA GeForce FX-optimized model.
VS_3_0 = Shader Model 3.

=External links=

3D computer graphics | Microsoft APIs

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Pixel Shader Comparison

Vertex Shader Comparison