global_settings { 
  max_trace_level 30 
  string_encoding "ISO8859_1"
  assumed_gamma 1.0
  ambient_light  1
  }

#default { finish { ambient 1 diffuse 0 } }

camera { location <0,14,0>
 up z
 direction -y
 right x
 look_at <0,0,0>
 orthographic 
}

#declare foregro=rgb<2/3,1/3,0.8>;
#declare b1=rgb<1/3,0,0>;
#declare b2=rgb<0,2/3,0>;
#declare b3=rgb<0,0,1>;
#declare b4=rgb<1/3,2/3,1>;
plane { y,0 
 pigment { square
 pigment { color b1 }
 pigment { color b2 }
 pigment { color b3 }
 pigment { color b4 }
 }
}

#declare loop=-3;
#while (loop<4)
disc { <loop*2,1,4>,y,1 pigment { color foregro transmit loop } }

#if (loop<3)
disc { <loop*2+1,1,-4>,y,1 pigment { color foregro transmit loop+0.5 } }
#end

disc { <loop*2,1,2>,y,1 pigment { square
 pigment { color max(0,(1-loop))*foregro+loop*b1 }
 pigment { color max(0,(1-loop))*foregro+loop*b2 }
 pigment { color max(0,(1-loop))*foregro+loop*b3 }
 pigment { color max(0,(1-loop))*foregro+loop*b4 }
} }
#if (loop<3)
disc { <loop*2+1,1,-2>,y,1 pigment { square
 pigment { color max(0,(1-loop-0.5))*foregro+(loop+0.5)*b1 }
 pigment { color max(0,(1-loop-0.5))*foregro+(loop+0.5)*b2 }
 pigment { color max(0,(1-loop-0.5))*foregro+(loop+0.5)*b3 }
 pigment { color max(0,(1-loop-0.5))*foregro+(loop+0.5)*b4 }
} }
#end

disc { <loop*2,1,6>,y,1 pigment { square
 pigment { color (1-loop)*foregro+loop*b1 }
 pigment { color (1-loop)*foregro+loop*b2 }
 pigment { color (1-loop)*foregro+loop*b3 }
 pigment { color (1-loop)*foregro+loop*b4 }
} }
#if (loop<3)
disc { <loop*2+1,1,-6>,y,1 pigment { square
 pigment { color (1-loop-0.5)*foregro+(loop+0.5)*b1 }
 pigment { color (1-loop-0.5)*foregro+(loop+0.5)*b2 }
 pigment { color (1-loop-0.5)*foregro+(loop+0.5)*b3 }
 pigment { color (1-loop-0.5)*foregro+(loop+0.5)*b4 }
} }
#end
#declare loop=loop+1;
#end

text {
  ttf 
  "arialbd.ttf"
  concat(chr(165)," = (1-t).",chr(169)," + t.",chr(174))
  0.01
  0
  texture { pigment { rgb <1,1,0> } }
  rotate <90,0,0>
  translate <-3.5,1,-0.35>
  }

box { <-5,0,-0.8>,<5,0.5,0.8>
texture { pigment { rgb <0,0,0.5> } }
}