source: GTP/branches/IllumWPdeliver2008dec/IlluminationWP/demos/OgreGames/SpaceStation/Media/GTPEnvMap/GTPEnvMap.hlsl @ 3255

float4 readCubeMap(samplerCUBE cm, float3 coord)                
{
        float4 color = texCUBE( cm, float3(coord.xy, - coord.z) );
        color.a = 1;
        return color;
}

float readDistanceCubeMap(samplerCUBE dcm, float3 coord)                
{
        float dist = texCUBE(dcm, float3(coord.xy, - coord.z)).a;
        if(dist == 0) dist = 1000; ///sky
        return dist;
}

#define SECANT_ITERATIONCOUNT 20

float3 Hit( float3 x, float3 R, samplerCUBE mp )
{
        float rl = readDistanceCubeMap( mp, R);                         // |r|
        
        float ppp = length( x ) /  readDistanceCubeMap( mp, x);                 // |p|/|p’|
        float dun = 0, pun = ppp, dov = 0, pov = 0;
        float dl = rl * ( 1 - ppp );                                                    // eq. 2
        float3 l = x + R * dl;                                                                  // ray equation

        // iteration
        for( int i = 0; i < SECANT_ITERATIONCOUNT ; i++ )
        {
                float llp = length( l ) / readDistanceCubeMap( mp, l);          // |l|/|l’|
                if ( llp < 0.999f )                                                                     // undershooting
                {
                        dun = dl; pun = llp;                                                    // last undershooting
                        dl += ( dov == 0 ) ? rl * ( 1 - llp ) :                 // eq. 2
                                ( dl - dov ) * ( 1 - llp ) / ( llp - pov );     // eq. 3
                } else if ( llp > 1.001f )                                                      // overshooting
                {
                        dov = dl; pov = llp;                                                    // last overshooting
                        dl += ( dl -dun ) * ( 1 - llp ) / ( llp - pun );// eq. 3
                }
                l = x + R * dl;                                                                         // ray equation
        }
        return l;                                                                                               // computed hit point
}


struct Shaded_OUT
{
 float4 vPos : POSITION;
 float4 wNormal : TEXCOORD0;
 float4 wPos    : TEXCOORD1; 
};


float4 EnvMap_Default_PS(Shaded_OUT IN,
                                                uniform samplerCUBE CubeMap : register(s0),
                                                uniform float3 cameraPos) : COLOR0
{
        float3 N = normalize(IN.wNormal.xyz);
        float3 V = normalize(IN.wPos.xyz - cameraPos);
        float3 R = reflect( V, N);      
        
        return readCubeMap(CubeMap, R );        
}

float4  EnvMap_Localized_Reflection_PS( Shaded_OUT IN,
                                                                                uniform samplerCUBE CubeMap : register(s0),
                                                                                uniform samplerCUBE DistanceMap : register(s1),
                                                                                uniform float3 cameraPos,
                                                                                uniform float3 lastCenter,              
                                                                                uniform float sFresnel,
                                                                                uniform float sRefraction ) :COLOR0
{
        float3 N = normalize(IN.wNormal.xyz);
        float3 RR;      
        float3 V = normalize(IN.wPos.xyz - cameraPos);
        float3 cubePos = IN.wPos.xyz - lastCenter;
        float3 R = reflect( V, N);      
                
        RR = R;
        RR = Hit(cubePos, R, DistanceMap);
        
        return readCubeMap(CubeMap, RR );       
}

float4  EnvMap_Localized_Refraction_PS( Shaded_OUT IN,
                                                                                uniform samplerCUBE CubeMap : register(s0),
                                                                                uniform samplerCUBE DistanceMap : register(s1),
                                                                                uniform float3 cameraPos,
                                                                                uniform float3 lastCenter,              
                                                                                uniform float sFresnel,
                                                                                uniform float sRefraction ) :COLOR0
{
        float4 Color = 0;
        float3 N = normalize(IN.wNormal.xyz);
        float3 RR, TT;  
        float3 V = normalize(IN.wPos.xyz - cameraPos);
        float3 cubePos = IN.wPos.xyz - lastCenter;
        float3 R = reflect( V, N);      
        float3 T = refract(V, N, sRefraction);

                
        RR = R; TT = T; 
        RR = Hit(cubePos, R, DistanceMap);
        float4 reflectcolor = readCubeMap(CubeMap, RR );                
        
        if(dot(T,T)!=0)
        {
                TT = Hit(cubePos, T, DistanceMap);
                float4 refractcolor = readCubeMap(CubeMap, TT );                
        
                float cos_theta = -dot(V, N);
                float F = (sFresnel + pow(1 - cos_theta, 5.0f) * (1 - sFresnel));
                F = saturate(F);
                Color =  (F * reflectcolor + (1 - F) * refractcolor);
        }
        else
        {
                Color = reflectcolor;
        }
  return Color;
}


float4 EnvMap_LocalizedMetal_PS(  Shaded_OUT IN,
                                                                        uniform samplerCUBE CubeMap : register(s0),
                                                                        uniform samplerCUBE DistanceMap : register(s1),
                                                                        uniform float3 cameraPos,
                                                                        uniform float3 lastCenter,
                                                                        uniform float3 F0 ):COLOR0
{       
        float4 Color;
        float3 N = normalize(IN.wNormal.xyz);
        float3 RR;      
        float3 V = normalize(IN.wPos.xyz - cameraPos);
        float3 cubePos = IN.wPos.xyz - lastCenter;
        float3 R = reflect( V, N);
                
        RR = R; 
        RR = Hit(cubePos, R, DistanceMap);
        Color = readCubeMap(CubeMap, RR);
        //Color = readDistanceCubeMap(DistanceMap, cubePos)/300.0;
        //return Color;
        
        float ctheta_in = dot(N, R);
        float ctheta_out = dot(N, -V);

        float3 F = 0;
        
        // compute F,P,G
        //if ( ctheta_in > 0 && ctheta_out > 0 )
        {
                float3 H = normalize(R - V);    // felezõvektor
                float cbeta  = dot(H,R);                
                //F = ( (n-1)*(n-1) + pow(1-cbeta,5) * 4*n + k*k) / ( (n+1)*(n+1) + k*k );
                //float3 F0 = ((n-1)*(n-1) + k*k) / ( (n+1)*(n+1) + k*k );
                //float3 F1 = float3(1.0f,1.0f,1.0f) - F0;
                F = F0 + (1 - F0) * pow(1 - cbeta, 5);
        }
                
        return Color * float4(F,1);     
}