sky_sphere
{
  pigment
  {
    color rgb 1
  }
}

light_source
{
  <0, 1000, -1000>
  color rgb 1
}

camera
{
  location <2, 10, -20>
  look_at <2, 0, 2>
  angle 20
}

#declare xdem=5;
#declare zdem=5;
#declare sp=1;
#declare norm=<0, 0, 0>;

#declare vertices=array[zdem][xdem]
{
    { <0, 0.5,  0>, <1, 0.7,  0>, <2, 0.85, 0>, <3, 0.93, 0>, <4, 0.76, 0>},
    { <0, 0.42, 1>, <1, 0.65, 1>, <2, 0.71, 1>, <3, 0.91, 1>, <4, 0.69, 1>},
    { <0, 0.35, 2>, <1, 0.54, 2>, <2, 0.6,  2>, <3, 0.87, 2>, <4, 0.58, 2>},
    { <0, 0.39, 3>, <1, 0.69, 3>, <2, 0.74, 3>, <3, 1.03, 3>, <4, 0.75, 3>},
    { <0, 0.51, 4>, <1, 0.88, 4>, <2, 0.95, 4>, <3, 1.23, 4>, <4, 0.92, 4>}
}


#declare relief=
mesh2
{
  vertex_vectors
  {
    xdem*zdem,
    #declare a=0;
    #while (a<zdem)
      #declare b=0;
      #while (b<xdem)
        vertices[a][b]
        #if (a<zdem-1 & b<xdem-1)
          ,
        #end
        #declare b=b+1;
      #end
      #declare a=a+1;
    #end
  }
  face_indices
  {
    (xdem-1)*(zdem-1)*2,
    <0, 1, 5>, <5, 1, 6>, <1, 2, 6>, <6, 2, 7>, <2, 3, 7>, <7, 3, 8>, <3, 4, 8>, <8, 4, 9>,
    <5, 6, 10>, <10, 6, 11>, <6, 7, 11>, <11, 7, 12>, <7, 8, 12>, <12, 8, 13>, <8, 9, 13>, <13, 9, 14>,
    <10, 11, 15>, <15, 11, 16>, <11, 12, 16>, <16, 12, 17>, <12, 13, 17>, <17, 13, 18>, <13, 14, 18>, <18, 14, 19>,
    <15, 16, 20>, <20, 16, 21>, <16, 17, 21>, <21, 17, 22>, <17, 18, 22>, <22, 18, 23>, <18, 19, 23>, <23, 19, 24>
  }
  texture
  {
    pigment { color rgb <0.5, 0.2, 0.9> }
    finish { ambient 0.1 diffuse 1 brilliance 0.4 }
  }
}


#declare normals=array[zdem][xdem];    
    
#declare a=0;
#while (a<zdem)
  #declare b=0;
  #while (b<xdem)
    #declare ep=vertices[a][b];
    #declare avx=0;
    #declare avy=0;
    #declare avz=0;
    #declare c=0;
    #declare i=0;
    #while (c<8)
      #declare svp=ep+(sp/2)*<int(sin(c*45)*(pi/180)), 10, int(cos(c*45)*(pi/180))>;
      #declare svt=trace(relief, svp, -y, norm);
      #if (norm.x!=0 & norm.y!=0 & norm.z!=0)
        #warning "OK!"
        #declare avx=avx+norm.x;
        #declare avy=avy+norm.y;
        #declare avz=avz+norm.z;
        #declare i=i+1;
      #end
      #declare c=c+1;
    #end
    #declare normals[a][b]=<avx/i, avy/i, avz/i>;        
    #declare b=b+1;
  #end
  #declare a=a+1;
#end


#declare relief_s=
mesh2
{
  vertex_vectors
  {
    xdem*zdem,
    #declare a=0;
    #while (a<zdem)
      #declare b=0;
      #while (b<xdem)
        vertices[a][b]
        #if (a<zdem-1 & b<xdem-1)
          ,
        #end
        #declare b=b+1;
      #end
      #declare a=a+1;
    #end
  }
  normal_vectors
  {
    xdem*zdem,
    #declare a=0;
    #while (a<zdem)
      #declare b=0;
      #while (b<xdem)
        normals[a][b]
        #if (a<zdem-1 & b<xdem-1)
          ,
        #end 
        #declare b=b+1;
      #end
      #declare a=a+1;
    #end
  }      
  face_indices
  {
    (xdem-1)*(zdem-1)*2,
    <0, 1, 5>, <5, 1, 6>, <1, 2, 6>, <6, 2, 7>, <2, 3, 7>, <7, 3, 8>, <3, 4, 8>, <8, 4, 9>,
    <5, 6, 10>, <10, 6, 11>, <6, 7, 11>, <11, 7, 12>, <7, 8, 12>, <12, 8, 13>, <8, 9, 13>, <13, 9, 14>,
    <10, 11, 15>, <15, 11, 16>, <11, 12, 16>, <16, 12, 17>, <12, 13, 17>, <17, 13, 18>, <13, 14, 18>, <18, 14, 19>,
    <15, 16, 20>, <20, 16, 21>, <16, 17, 21>, <21, 17, 22>, <17, 18, 22>, <22, 18, 23>, <18, 19, 23>, <23, 19, 24>
  }
  texture
  {
    pigment { color rgb <0.5, 0.2, 0.9> }
    finish { ambient 0.1 diffuse 1 brilliance 1}
  }
}


object { relief } // change this to relief_s in order to render the smoothed version of the mesh2