// CASSINI / Lemniscate of Bernoulli '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 <10, 30, -30>
  look_at <0, 0, 0>
  angle 11
  }

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

isosurface {
  function {pow(x*x+y*y+z*z-16,2)-16*(x*x-y*y-z*z+16)}
  threshold 0
  max_gradient 5000
  contained_by {box {<-8, -5, -9>, <8, 5, 9>}}
  //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 <1.2, 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>}