用Shader实现标准光照模型

用Shader实现标准光照模型

DXSDK里光照模型的讲解依然停留在DX9的固定管线时代; DX10及DX11的文档里只是API文档,居然一点基于Shader的光照模型讲解文章都未见,失望.

无奈, 打开NV官网,找到这样一篇文章, 基于Cg语言的Shader标准光照模型讲解, Bingo!

了解标准光照基础知识后,就不会面对MAX的材质系统, Maya的Node Based Material System感到陌生.

这里贴下这组光照模型的Cg代码

 

float4x4 matViewProjection;

float3 GlobalAmbient;

float3 LightColor;

float3 LightPosition;

float4 EyePosition;

float3 Ke;

float3 Ka;

float3 Kd;

float3 Ks;

float Shininess;

void vs_main( 

   in float4 InPosition : POSITION,

   in float3 InNormal : NORMAL,

   out float4 OutPosition : POSITION,

   out float4 OutColor : COLOR0

 )

{

   OutPosition = mul( InPosition, matViewProjection );

   float3 P = InPosition.xyz;

   float3 N = InNormal;

   // Compute the emissive term

   float3 Emissive = Ke;

    // Compute the ambient term

   float3 Ambient = Ka * GlobalAmbient;

   // Compute the diffuse term

   float3 L = normalize( LightPosition - P );

   float DiffuseLight = max( dot( N, L ), 0 );

   float3 Diffuse = Kd * LightColor * DiffuseLight;

   // Compute the specular term

   float3 V = normalize( EyePosition - P );

   float3 H = normalize( L + V );

   float SpecularLight = pow( max( dot( N, H ), 0 ), Shininess );

   if ( DiffuseLight <= 0 )  SpecularLight = 0;

   float3 Specular = Ks * LightColor * SpecularLight;

   OutColor.xyz = Emissive +  Ambient + Diffuse + Specular;

   OutColor.w = 1;   

}

float4 ps_main( float4 OutColor : COLOR0 ) : COLOR0

{   

   return( OutColor );

}