Direct3D中的Shader是这样的：
1. ASM Shader是最元老的也是DX8主要使用Shader
2. fxc编译器可以同时编译ASM,HLSL和fx脚本,其中HLSL和fx可以查看编译后的GPU汇编代码
3. D3D9中，fx是HLSL的一种渲染脚本，简化了HLSL设置及常量绑定，并且附带RenderStateBlock及设置
但只能用于制作简单的Shader
4. DirectXSDK中有一个概念混淆：C++例子中的BasicHLSL使用的其实还是fx，HLSLwithoutEffects例子才是真正的纯HLSL
5.fx与HLSL程序鉴别：
使用fx程序必定含有：D3DXCreateEffectXXX 系列函数， ID3DXEffect对象，渲染中能看到SetTechnique，BeginPass，EndPass之类的字眼
使用纯HLSL程序含有：D3DXCompileShader，ID3DXConstantTable对象，GetConstantByName，GetConstantDesc之类的字眼
6. 在fx中包含有 VertexShader，PixelShader代码及profile，entry，RenderState设置及简单的绘制过程(pass)。一次编译后，VS,PS,Texture,Sampler及常量都是在ID3DXEffect对象中自动完成，无需手动设置。
7. HLSL可以将VS及PS代码写入1个.hlsl文件。注意，以下这种代码可以在HLSL中编译过，但实际没有任何效果
1: sampler_state
2: { 3: Texture = <tex>;
4: MipFilter = LINEAR;
5: MinFilter = LINEAR;
6: MagFilter = LINEAR;
7: };
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这点可以参考AMD RenderMonkey中只在shader中使用sampler而忽略texture。
8. fx中往shader设置纹理使用的是ID3DXBaseEffect::SetTexture下的这个函数
1: HRESULT SetTexture(
2: D3DXHANDLE hParameter,
3: LPDIRECT3DBASETEXTURE9 pTexture
4: );
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.csharpcode .preproc { color: #cc6633; }
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但是在HLSL中，这点就变得很麻烦，需要手动设置，可以参考这篇文章
Shader代码片段：
1: sampler Samp0 = sampler_state
2: { 3: Texture = <Tex0>;
4: MipFilter = LINEAR;
5: MinFilter = LINEAR;
6: MagFilter = LINEAR;
7: };
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{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
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width: 100%;
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.csharpcode .lnum { color: #606060; }
编译HLSL代码后得到ConstantTable，然后取出句柄：
1: ScalarHandle = pixelConstTable->GetConstantByName(0, "Scalar");
2:
3: Samp0Handle = pixelConstTable->GetConstantByName(0, "Samp0");
4:
5: Samp1Handle = pixelConstTable->GetConstantByName(0, "Samp1");
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color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
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}
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.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
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width: 100%;
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.csharpcode .lnum { color: #606060; }
再从句柄取出symbol的描述：
1: UINT count;
2:
3: pixelConstTable->GetConstantDesc(Samp0Handle, & Samp0Desc, &count);
4:
5: pixelConstTable->GetConstantDesc(Samp1Handle, & Samp1Desc, &count);
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color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
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width: 100%;
margin: 0em;
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.csharpcode .lnum { color: #606060; }
通过上面的描述，将纹理变量的寄存器偏移作为纹理的stage
8. 优化常量设置速度的方法一般就是根据字符串取出句柄，以后每次渲染时，只通过句柄设置。但ID3DXConstantTable最后还是通过
IDirect3DDevice9::SetPixelShaderConstantX 系列函数来实现的
1: HRESULT SetPixelShaderConstantF(
2: UINT StartRegister,
3: CONST float * pConstantData,
4: UINT Vector4fCount
5: );
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color: black;
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background-color: #ffffff;
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}
.csharpcode pre { margin: 0em; }
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.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
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width: 100%;
margin: 0em;
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.csharpcode .lnum { color: #606060; }
9. HLSL将一段包含VS和PS代码编译完成后，将得到VS和PS两个单独的ID3DXConstantTable