dx10之模拟DX9

dx10之模拟DX9

Fixed-function Lighting Pipeline
ColorsOutput CalcLighting( float3 worldNormal, float3 worldPos, float3 cameraPos )
{
    ColorsOutput output = (ColorsOutput)0.0;
   
    for(int i=0; i<8; i++)
{
     //光线方向
        float3 toLight = g_lights[i].Position.xyz - worldPos;
         //离光源距离
        float lightDist = length( toLight );
         //atten＝（1/(a[2]*d*d+a[1]*d+a[1])
        float fAtten = 1.0/dot( g_lights[i].Atten, float4(1,lightDist,lightDist*lightDist,0) );
        float3 lightDir = normalize( toLight );
         //H
        float3 halfAngle = normalize( normalize(-cameraPos) + lightDir );
       
         //Phong方程，逐顶点光照
        output.Diffuse += max(0,dot( lightDir, worldNormal ) * g_lights[i].Diffuse * fAtten) + g_lights[i].Ambient;
        output.Specular += max(0,pow( dot( halfAngle, worldNormal ), 64 ) * g_lights[i].Specular * fAtten );
    }
   
    return output;
}
简单ALPHA测试
//
// PS for rendering with alpha test
//
float4 PSAlphaTestmain(PSSceneIn input) : COLOR0
{       
         float4 color =  tex2D( g_samLinear, g_txDiffuse, input.tex ) * input.colorD;
         if( color.a < 0.5 )
                 discard;
         return color;
}
雾化：

//
// Calculates fog factor based upon distance
//
// E is defined as the base of the natural logarithm (2.71828)
float CalcFogFactor( float d )
{
         float fogCoeff = 1.0;
        
         if( FOGMODE_LINEAR == g_fogMode )
         {
                 fogCoeff = (g_fogEnd - d)/(g_fogEnd - g_fogStart);
         }
         else if( FOGMODE_EXP == g_fogMode )
         {
                 fogCoeff = 1.0 / pow( E, d*g_fogDensity );
         }
         else if( FOGMODE_EXP2 == g_fogMode )
         {
                 fogCoeff = 1.0 / pow( E, d*d*g_fogDensity*g_fogDensity );
         }
        
         return clamp( fogCoeff, 0, 1 );
}

Finally, the pixel shader uses the fog factor to determine how much of the original color and how much of the fog color to output to the pixel.

最后，PS使用雾化参数确定雾颜色和纹理颜色的混合程度。
return fog * normalColor + (1.0 - fog)*g_fogColor;