High Level Shader Language

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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.

1 Shader model comparison
- 1.1 Pixel shader comparison
- 1.2 Vertex shader comparison
2 External links
3 Footnotes

[edit] Shader model comparison

[edit] Pixel shader comparison

	PS_2_0	PS_2_a	PS_2_b	PS_3_0	PS_4_0^[1]
Dependent texture limit	4	No Limit	4	No Limit	No Limit
Texture instruction limit	32	Unlimited	Unlimited	Unlimited	Unlimited
Position register	No	No	No	Yes	Yes
Instruction slots	32 + 64	512	512	≥ 512	≥ 65536
Executed instructions	32 + 64	512	512	≥65536	Unlimited
Interpolated registers	2 + 8	2 + 8	2 + 8	10	32
Instruction predication	No	Yes	No	Yes	Yes
Index input registers	No	No	No	Yes	Yes
Temp registers	12	22	32	32	4096
Constant registers	32	32	32	224	16x4096
Arbitrary swizzling	No	Yes	No	Yes	Yes
Gradient instructions	No	Yes	No	Yes	Yes
Loop count register	No	No	No	Yes	Yes
Face register (2-sided lighting)	No	No	No	Yes	Yes
Dynamic flow control	No	No	No	24	Yes

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.
PS_4_0 = Shader Model 4.

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

[edit] Vertex shader comparison

	VS_2_0	VS_2_a	VS_3_0	VS_4_0^[1]
# of instruction slots	256	256	>=512	>=4096
Max # of instructions executed	65535	65535	>=65535	>=65536 (?)
Instruction Predication	No	Yes	Yes	Yes
Temp Registers	12	13	32	4096
# constant registers	>=256	>=256	>=256	16x4096
Static Flow Control	Yes	Yes	Yes	Yes
Dynamic Flow Control	No	Yes	Yes	Yes
Dynamic Flow Control Depth	No	24	24	Yes
Vertex Texture Fetch	No	No	Yes	Yes
# of texture samplers	No	No	4	128
Geometry Instancing Support	No	No	Yes	Yes