varying vec3 N;
varying vec3 v;
uniform int nLights;
uniform float scaling;

uniform vec3 light_positions[8];
uniform vec4 light_colours_ambient[8];
uniform vec4 light_colours_specular[8];
uniform vec4 light_colours_diffuse[8];

varying vec4 E;
varying vec4 theVert;

varying float size;

uniform bool shadowsOn;
uniform int shadowQuality;

uniform sampler2D ShadowMap;
uniform float xPixelOffset;
uniform float yPixelOffset;

uniform bool ssaoOn;
uniform sampler2D SSAOMap;
uniform float screenWidth;
uniform float screenHeight;

float lookup(vec2 offSet, float zoffset)
{
   vec4 theVert2 = theVert;
   vec4 tCoord = vec4(0.0,0.0,1.0,0.0);
   tCoord = gl_ModelViewMatrixInverse * (tCoord);
   theVert2 += zoffset*tCoord;
   theVert2.w = 1.0;
   vec4 shadowCoord = gl_TextureMatrix[2]*theVert2;

   vec4 coord = shadowCoord + vec4(offSet.x * xPixelOffset * shadowCoord.w, offSet.y * yPixelOffset * shadowCoord.w, 0.0005, 0.0);
   float depth = texture2D(ShadowMap, coord.xy ).z;
   float R = coord.p / coord.q;
   return (R <= depth) ? 1.0 : 0.0;
}

void main(void) {
  vec4 color = vec4(gl_Color);

   vec3 L;
   vec3 E2;
   vec3 R;
   vec4 Iamb =vec4(0.0,0.0,0.0,0.0);
   vec4 Idiff=vec4(0.0,0.0,0.0,0.0);
   vec4 Ispec=vec4(0.0,0.0,0.0,0.0);
   int i;

  float x = gl_TexCoord[0].x;
  float y = gl_TexCoord[0].y;
  float zz = 1.0 - x*x - y*y;
  float z = sqrt(zz);

  if(zz <= 0.06)
      discard;

  vec4 pos = E;
  pos.z += z*scaling*size;
  mat4 projMat = gl_ProjectionMatrix;
  pos = projMat * pos;

  gl_FragDepth = (pos.z / pos.w + 1.0) / 2.0;

   vec3 norm = vec3(x,y,z);

   E2 = normalize(-v);
   for (i = 0; i<8; i++) {
     if(i < nLights){
       L = normalize(light_positions[i].xyz);   
       R = normalize(-reflect(L,norm));
       //calculate Ambient Term:  
       Iamb += light_colours_ambient[i];
       //calculate Diffuse Term:  
       Idiff += light_colours_diffuse[i] * max(dot(norm,L), 0.0);
       // calculate Specular Term:
       if(gl_FrontFacing){
         float y = max(max(light_colours_specular[i].r,light_colours_specular[i].g),light_colours_specular[i].b);
         Ispec += light_colours_specular[i] * pow(max(dot(R,E2),0.0),0.3*gl_FrontMaterial.shininess);
         Ispec.a *= y;
       }
     }
   }

   float shadow = 0.0;

   if(!shadowsOn){
     shadow = 1.0;
   }else{
     if(shadowQuality==0){
       // Quick jaggy-shadows
       shadow += lookup(vec2(0,0),z*scaling*size);
       shadow += 0.2;
     }else if(shadowQuality==1){
       // PCF soft-shadows
       if(shadowsOn){
         float x,y;
         for (y = -1.5 ; y <=1.5 ; y+=1.0)
           for (x = -1.5 ; x <=1.5 ; x+=1.0)
             shadow += lookup(vec2(x*0.5,y*0.5),z*scaling*size);
         shadow /= 16.0 ;
         shadow += 0.2;
       } 
     }else{
       // PCF softer-shadows
       if(shadowsOn){
         float x,y;
         for (y = -3.5 ; y <=3.5 ; y+=1.0)
           for (x = -3.5 ; x <=3.5 ; x+=1.0)
             shadow += lookup(vec2(x*0.5,y*0.5),z*scaling*size);
         shadow /= 64.0 ;
         shadow += 0.2;
       } 
     } 
     shadow = clamp(shadow,0.0,1.0);
   }

  float att=1.0;
  if(ssaoOn){
    vec2 texCoord = vec2(gl_FragCoord.x/screenWidth,  gl_FragCoord.y/screenHeight);
    att = texture2D(SSAOMap, texCoord).r;
  }

  color = (gl_FrontMaterial.emission + 1.5*color* Iamb + 1.2*color* Idiff*shadow*att);

  if(shadow>0.5)
     color += Ispec;

   float fogFactor = (gl_Fog.end - gl_FogFragCoord+z*scaling*size)*gl_Fog.scale;
   fogFactor = clamp(fogFactor,0.0,1.0);

   gl_FragColor = mix(gl_Fog.color, color, fogFactor );

}