高级着色器语言

高级着色器语言（High Level Shader Language，简称HLSL），由微軟擁有及開發的一種語言，只能供微軟的Direct3D以及XNA使用。HLSL是GLSL的先辈，同時不能與OpenGL標準兼容。他跟Nvidia的Cg非常相似。

HLSL的主要作用為將一些複雜的圖像處理，快速而又有效率地在顯示卡上完成，與組合式或低階Shader Language相比，能降低在編寫複雜特殊效果時所發生編程錯誤的機會。

Shader model 比較

Pixel shader 比較

Pixel shader 版本	2.0	2.0a	2.0b	3.0	4.0
Dependent texture limit	8	Unlimited	8	Unlimited	Unlimited
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
Texture indirections	4	No limit	4	No Limit	No Limit
Interpolated registers	2 + 8	2 + 8	2 + 8	10	32
Instruction predication	No	Yes	No	Yes	No
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
Bitwise Operators	No	No	No	No	Yes
Native Integers	No	No	No	No	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.
• PS 4.0 = Shader Model 4.

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

Vertex shader 比較

Vertex shader 版本	VS 2.0	VS 2.0a	VS 3.0	VS 4.0
# of instruction slots	256	256	≥ 512	4096
Max # of instructions executed	65536	65536	65536	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	N/A	N/A	4	128
en:Geometry instancing support	No	No	Yes	Yes
Bitwise Operators	No	No	No	Yes
Native Integers	No	No	No	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.
• VS 4.0 = Shader Model 4.

範例

灰階貼圖用

• 灰階值 = 0.3 x 紅 + 0.59 x 綠 + 0.11 x 藍

sampler2D Texture0;

float4 ps_main( float2 texCoord  : TEXCOORD0 ) : COLOR
{
   float4 _inColor = tex2D( Texture0, texCoord );
   float gray = 0.3*_inColor.x + 0.59*_inColor.y + 0.11*_inColor.z;
   float4 _outColor = float4(gray, gray, gray, 1.0);
   
   return _outColor;
}

外部連結

• Introduction to the DirectX 9 High-Level Shader Language (MSDN Library)
• HLSL Introduction
• Shader Model Comparison at Beyond3D
• Riemer's HLSL Introduction & Tutorial with lots of sample code