Ray.sha

//Cg

void vshader( 
  in uniform float4x4 mat_modelproj, 
  in float4 vtx_position: POSITION, 
  out float4 l_position: POSITION,
  out float4 l_pos) 
{ 
  l_pos=vtx_position;  
  l_position = mul(mat_modelproj, vtx_position);
} 

float simplex3(in float3 loc, out float3 der, uniform sampler1D vecTex){
    const int d=3;
    const float f=0.333333333333;
    const float g=0.166666666667;
    const float cornerToFaceSquared=0.703125*.9;
    const float valueScaler=15.4423881554;
    const int vecCount=12;
    
    const float3 randomizerVec=float3(181.4813,787.7541,1646.2698);
    
    float s=(loc.x+loc.y+loc.z)*f;
    int3 intSkewLoc=floor(loc+s);
    float t2=(intSkewLoc.x+intSkewLoc.y+intSkewLoc.z)*g;
    float3 cellDist=loc-intSkewLoc+t2;

    float t=max(0,cornerToFaceSquared-dot(cellDist,cellDist));

    float3 vx=intSkewLoc*randomizerVec;
    float index=vx.x+vx.y+vx.z;
    float3 vec=tex1D(vecTex,frac(index/vecCount)).xyz-1.0;
    float gr=dot(vec,cellDist);
    float t4=pow(t,4);
    float n=gr*t4;
    der=vec*t4-gr*8*pow(t,3)*cellDist;

    float skewOffset=g;
    float3 c=cellDist;
    int3 intLoc=intSkewLoc;
    
    for (int i=1; i<=d; i++){
        float m=max(max(c.x,c.y),c.z);
        /*
        bool3 b=c>=float3(m);
        c = b ? -1.0 : c;
        intLoc=b ? intLoc+1 : intLoc;
        */
        if (c.x>=m) {c.x=-1;intLoc.x++;}
        else if (c.y>=m) {c.y=-1;intLoc.y++;}
        else{c.z=-1;intLoc.z++;}
        

        float3 u=cellDist-(intLoc-intSkewLoc)+skewOffset;
        t=max(0,cornerToFaceSquared-dot(u,u));
        
        vx=(intLoc)*randomizerVec;
        index=vx.x+vx.y+vx.z;
        vec=tex1D(vecTex,frac(index/vecCount)).xyz-1.0;
        gr=dot(vec,u);
        t4=pow(t,4);
        n+=gr*t4;
        der+=vec*t4-gr*8*pow(t,3)*u;

        skewOffset+=g;
    }
    der*=valueScaler;
    return n*valueScaler;
}


float4 densityFull(float3 pos, int count, uniform sampler1D vecTex, float threshold){
  float4 v=float4(0,0,0,0);
  int i;
  for (i=0 ; i<count ; i++){
      float freqScaler=4.0*pow(2.0,i);
      float3 loc=pos*freqScaler;
      float3 der;
      float v2=simplex3(loc,der,vecTex);
      der*=freqScaler;
      v+=float4(der*freqScaler,v2-threshold)*.5*pow(.5,i);
  }

  return v;
}


float3 toWorld(float4x4 camMat, float3 dir, float z){
return mul(camMat,float4(dir*z,1)).xyz;
}

void fshader( 
  in float4 l_pos,
  in sampler1D tex_0: TEXUNIT0,
  //uniform float4x4 trans_cam_to_world,
  
  //uniform float4x4 wstrans_cam,
  
  uniform float4 k_camMat1,
  uniform float4 k_camMat2,
  uniform float4 k_camMat3,
  uniform float4 k_camMat4,
  uniform float4 k_threshold,
  
  out float4 o_color: COLOR) 
{    
  float4 c;
  float3 dir=float3(l_pos.x,1,l_pos.z);
  
  vec3 lightSource=vec3(.5,.5,-1);
  //vec3 camLoc=k_cam.xyz;
  vec3 groundNorm;
  
  //float4x4 m=wstrans_cam;
  float4x4 m=float4x4(k_camMat1,k_camMat2,k_camMat3,k_camMat4);
  
  float t=k_threshold.x;
  
  float3 hitPos ; 
  
  bool hit=false;
  
  int i;
  const int loopCount=15;
  
  const float maxDepth=0.8;
  
  const float minDepth=.0;
  float z=minDepth;
  
  float zHit=0;
  float zMiss=0;
  float4 zHitVal;
  float4 zMissVal=densityFull(toWorld(m,dir,0),1,tex_0,t);
  hit=zMissVal.w>0;
  
  
  float3 checkPos;
  float4 v;
  
  float sampleOffset=pow(minDepth/maxDepth,.5);
  sampleOffset=sampleOffset*(loopCount/(1-sampleOffset));
  
  float zStep=(maxDepth-minDepth)/loopCount;
  float stepScalar;
   
  float vilibility=1;
  
  for (i = 0; i <= loopCount; i++){
    if (!hit){
        float3 lastPos=checkPos;
        checkPos=toWorld(m,dir,z);
        
        v=densityFull(checkPos,1,tex_0,t);
        if (v.w>0){
          hit=true;
        } else {
          zMiss=z;
          zMissVal=v;
          stepScalar=(-zMissVal.w);
          z+=stepScalar*.4+(.08+2.0*pow(float(i)/loopCount,3))*zStep;
        }
      }
    }
    
    if (!hit){discard;}
    if (z==0){
    o_color=float4(1,0,0,1);
    }else{
    
    
    zHit=z;
    zHitVal=v;
    
    int rloopCount=4;
    
    for (i = 1; i <= rloopCount; i++){
        z=(zHit+zMiss)*.5;
        checkPos=toWorld(m,dir,z);
        v=densityFull(checkPos,1,tex_0,t);
        if ((v.w)>0){
            zHit=z;
            zHitVal=v;
        } else {
            zMiss=z;
            zMissVal=v;
        }
    }
    
    
    

    
    
    float f=zHitVal.w-zMissVal.w;
    f=-zMissVal.w/f;
    
    z=zHit*f+zMiss*(1-f);
    checkPos=toWorld(m,dir,z);
    float4 v2=densityFull(checkPos,6,tex_0,t);
    
    groundNorm=normalize(v.xyz+v2.xyz*.01);
    //groundNorm=normalize(-(zHitVal.xyz*f+zMissVal.xyz*(1-f)));

    vilibility=pow(2.718,-5*z);
    if (!hit){vilibility=0;}


    float3 camLoc=toWorld(m,dir,0);
    lightSource=normalize(lightSource);
    
    camLoc=normalize(camLoc.xyz-checkPos.xyz);
    
    vec3 hVec=normalize(lightSource + camLoc);
    
    //float NdotL=dot(lightSource,groundNorm);
    //float NdotH=dot(hVec,groundNorm);
    //vec4 l=lit(  NdotL, NdotH , 200 );
    float l=(1/(z*z))*.032;
    
    l=min(1,l);
    
    l=max(0,1-pow(dot(dir.xz,dir.xz),1)*1)*.8*l+l*.2;
    
    l*=clamp(dot(-camLoc,groundNorm),0,1);
    
    c=float4((length(checkPos-round(checkPos))*3-1)*10,1,.5,1);
    
    //c.xyz*=l.y*.9+l.z*0+.1;
    c.xyz*=l;

    c=lerp(float4(0,0,0,0),c,vilibility);
  
    o_color=c;
    }
}