// CASSINI / Cassinian Ovals '03.05
// By Tsutomu HIGO  E-mail: nj2t-hg@asahi-net.or.jp

#version 3.5;
global_settings {
  max_trace_level 4
  assumed_gamma 2.2
  }

camera {
  location <2, 30, -30>
  look_at <-0.25, -0.2, 0>
  angle 10
  }

light_source {<-50, 150, -75> color rgb <0.8, 0.8, 0.8>}

isosurface {
  function {pow(x*x+y*y+z*z,2)-4*z*z*x*x-pow(3,4)}
  threshold 0
  max_gradient 5000
  contained_by {box {<-8, -3, -8>, <8, 3, 8>}}
  //open
  texture {
    pigment {
      gradient z
      color_map {
        [ 0 color rgbt <0.3, 0.3, 1, 0> ]
        [ 0.05 color rgbt <1, 1, 0.8, 0.2> ]
        [ 1 color rgbt <2, 1.2, 0.5, 0.8> ]
        }
      }
    finish {
      ambient 0.2
      diffuse 1
      reflection 0
      specular 1
      phong 0.5
      brilliance 1
      }
    }
  scale 1/vlength(1)
  rotate <0, 0, 0>
  no_shadow
  }

background {color rgb <0, 0.2, 0.7>}