///////////////////////////////////////////////////////////////////////////////
//
//      ##  ######
//       ######  ###
//  ## ###############        Shark 3D Engine (www.shark3d.com)
//   ########## # # #
//    ########                Copyright (c) 1996-2006 Spinor GmbH.
//   ######### # # #          All rights reserved.
//  ##   ##########
//      ##
//
///////////////////////////////////////////////////////////////////////////////


#define NITERATION 5

struct PS_INPUT
{
    float3 worldV     : TEXCOORD0;
    float3 WNormal   : TEXCOORD1;
    float3 CUBEPos   : TEXCOORD2;
    float3 lastCenter :TEXCOORD3;
};

sampler distanceSamp: register(s0);


half3 Hit(samplerCUBE tex, half3 R, half3 p0)
{
        float rl = texCUBE(tex, R).r;
        float dp = rl - dot(p0, R);
        float3 p = p0 + R * dp;
        float ppp = length(p) / texCUBE(tex, p).r;
        float dun = 0, dov = 0, pun = ppp, pov = ppp;
        if (ppp < 1) dun = dp; else dov = dp;
        float dl = max( dp + rl * (1 - ppp), 0);
        float3 RR = p0 + R * dl;

        for(int i = 0; i < NITERATION; i++) {
                float ddl;
                float llp = length(RR) / texCUBE(tex, RR).r;
                if (llp < 1) {
                        dun = dl; pun = llp;
                        ddl = (dov == 0) ? rl * (1 - llp) :
                                (dl - dov) * (1 - llp)/(llp - pov);
                } else {
                        dov = dl; pov = llp;
                        ddl = (dun == 0) ? rl * (1 - llp) :
                                (dl - dun) * (1 - llp)/(llp - pun);
                }
                dl = max(dl + ddl, 0);
                RR = p0 + R * dl;
        }
        return RR;
}



///////////////////////////////////////////////////////////////////////////////
// Pixelshader
// Profile: 3x0


float4 main(PS_INPUT input): COLOR0
{
 const float g_RefractFactor = 0.95;

 // direction vector from light to shaded point in world space
 float3 V = normalize(input.worldV);
 // vertex normal in world space
 float3 N = normalize(input.WNormal);
 // refraction direction
 float3 R = refract(V, N, g_RefractFactor);
 // vertex position in cubemap space
 float3 X = input.CUBEPos;
 float3 dir = Hit(distanceSamp, R, X);
 //dir = input.lastCenter;
 //dir = N;
 //return float4(input.lastCenter,1);
// return texCUBE(distanceSamp,X).r;
 return float4(dir,1);
}

///////////////////////////////////////////////////////////////////////////////