HLSL中的宏定义

      HLSL一门2个小时就能学会，但需要很多年才能精通的语言。以前一直都没怎么用#define，今天看了xna内建effect的源码，才发现原来hlsl中的宏如此强大，并且见到了最疯狂的寄存器绑定，废话不多说，直接上代码吧:)

#ifdef SM4

// Macros for targetting shader model 4.0 (DX11/10)
#define BEGIN_CONSTANTS     cbuffer Parameters : register(b0) {
#define MATRIX_CONSTANTS    }; cbuffer ProjectionMatrix : register(b1) {
#define END_CONSTANTS       };

#define _vs(r)
#define _ps(r)
#define _cb(r)  : packoffset(r)

#define DECLARE_TEXTURE(Name, index) \
    Texture2D<float4> Name : register(t##index); \
    sampler Name##Sampler : register(s##index)

#define DECLARE_CUBEMAP(Name, index) \
    TextureCube<float4> Name : register(t##index); \
    sampler Name##Sampler : register(s##index)

#define SAMPLE_TEXTURE(Name, texCoord)  Name.Sample(Name##Sampler, texCoord)
#define SAMPLE_CUBEMAP(Name, texCoord)  Name.Sample(Name##Sampler, texCoord)

#else
// Macros for targetting shader model 2.0/3.0 (DX9)
#define BEGIN_CONSTANTS
#define MATRIX_CONSTANTS
#define END_CONSTANTS

#define _vs(r)  : register(vs, r)
#define _ps(r)  : register(ps, r)
#define _cb(r)

#define DECLARE_TEXTURE(Name, index) \
    texture2D Name; \
    sampler Name##Sampler : register(s##index) = sampler_state { Texture = (Name); };

#define DECLARE_CUBEMAP(Name, index) \
    textureCUBE Name; \
    sampler Name##Sampler : register(s##index) = sampler_state { Texture = (Name); };

#define SAMPLE_TEXTURE(Name, texCoord)  tex2D(Name##Sampler, texCoord)
#define SAMPLE_CUBEMAP(Name, texCoord)  texCUBE(Name##Sampler, texCoord)

#endif

#include "Macros.fxh"

DECLARE_TEXTURE(Texture, 0);

BEGIN_CONSTANTS

    float4 DiffuseColor             _vs(c0)  _ps(c1)  _cb(c0);
    float3 EmissiveColor            _vs(c1)  _ps(c2)  _cb(c1);
    float3 SpecularColor            _vs(c2)  _ps(c3)  _cb(c2);
    float  SpecularPower            _vs(c3)  _ps(c4)  _cb(c2.w);

    float3 DirLight0Direction       _vs(c4)  _ps(c5)  _cb(c3);
    float3 DirLight0DiffuseColor    _vs(c5)  _ps(c6)  _cb(c4);
    float3 DirLight0SpecularColor   _vs(c6)  _ps(c7)  _cb(c5);

    float3 DirLight1Direction       _vs(c7)  _ps(c8)  _cb(c6);
    float3 DirLight1DiffuseColor    _vs(c8)  _ps(c9)  _cb(c7);
    float3 DirLight1SpecularColor   _vs(c9)  _ps(c10) _cb(c8);

    float3 DirLight2Direction       _vs(c10) _ps(c11) _cb(c9);
    float3 DirLight2DiffuseColor    _vs(c11) _ps(c12) _cb(c10);
    float3 DirLight2SpecularColor   _vs(c12) _ps(c13) _cb(c11);

    float3 EyePosition              _vs(c13) _ps(c14) _cb(c12);

    float3 FogColor                          _ps(c0)  _cb(c13);
    float4 FogVector                _vs(c14)          _cb(c14);

    float4x4 World                  _vs(c19)          _cb(c15);
    float3x3 WorldInverseTranspose  _vs(c23)          _cb(c19);

MATRIX_CONSTANTS

    float4x4 WorldViewProj          _vs(c15)          _cb(c0);

END_CONSTANTS