// http://xahlee.org/3d/index.html

// POV-Ray transparency study

#include "colors.inc"

  light_source {
    100
    color White
  }

camera {
  location <5,6,-7>
  look_at  <0,0,0>
	translate -.8
}

//progressive phong
sphere {<-4,1,4>, 1 texture{pigment{color Green} finish {phong 0  }}}
sphere {<-2,1,4>, 1 texture{pigment{color Green} finish {phong 0.33}}}
sphere {< 0,1,4>, 1 texture{pigment{color Green} finish {phong 0.66}}}
sphere {< 2,1,4>, 1 texture{pigment{color Green} finish {phong 1  }}}

//progressive filter (transparency)
sphere {<-5,1,0>, 1 texture{pigment{color Yellow filter 0 }finish{phong .8}}}
sphere {<-3,1,0>, 1 texture{pigment{color Yellow filter .33 }finish{phong .8}}}
sphere {<-1,1,0>, 1 texture{pigment{color Yellow filter .66 }finish{phong .8}}}
sphere {< 1,1,0>, 1 texture{pigment{color Yellow filter 1 }finish{phong .8}}}

//progressive transmit (transparency)
sphere {<-5,1,-4>, 1 texture{pigment{color Red transmit 0 }finish{phong .8}}}
sphere {<-3,1,-4>, 1 texture{pigment{color Red transmit .33 }finish{phong .8}}}
sphere {<-1,1,-4>, 1 texture{pigment{color Red transmit .66 }finish{phong .8}}}
sphere {< 1,1,-4>, 1 texture{pigment{color Red transmit 1 }finish{phong .8}}}

plane { <0,1,0> // normal vector
      , 0 // distance from origin
  pigment {
    checker color White, color Gray
  }
}