File:Ferromagnetism vs orthomagnetism.png

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Below is the code to render this image using the Persistence of Vision Raytacer:

/*
================================================
Ferromagnetism and orthomagnetism
------------------------------------------------
Created by Søren Peo Pedersen - see my user page
at http://da.wikipedia.org/wiki/Bruger:Peo
================================================
*/

#declare MagnetFont="arialbd.ttf" // Font for the nomenclature on magnets
#declare NorthLtr="N";  // Letter to indicate north pole
#declare SouthLtr="S";  // Letter to indicate south pole

#declare ArrowHead=difference { // Head on arrows on sides of sample blocks:
  box {<0,-1,0>,<1,1,1> rotate <0,45,0> scale <4,1,1> translate <-.9,0,0>}
  plane {<-1,0,0>,.6}
  }

#declare DoubleArrow=merge {    // Define one complete double arrow
  box {<-.6,-1,-.015>,<.6,1,.015>}
  #object {ArrowHead}
  #object {ArrowHead scale <-1,1,1>}  
  }

#declare ArrowSet=merge {       // Declare a complete set of arrows
  #object {DoubleArrow translate <0,0,.3>}
  #object {DoubleArrow translate <0,0,-.3>}
  #object {DoubleArrow rotate <90,0,0>}
  }

#declare MagnetPair=union {   // One pair of a N and S magnetic pole
  // The magnet at the left-hand side of the image:
  box {<-15,-1,-1>,<-3,1,1> // A box shape
    pigment {
      object {
        text {ttf MagnetFont,NorthLtr,3,0 //... with letter for "north" on it
          scale 2 translate <-4.3,-.7,-1.5>
          }
        color rgb <1,0,0>
        color rgb .85
        }
      }
    finish {ambient .4}
    no_shadow
    no_reflection
    }
  // The magnet at the right-hand side of the image:
  box {<3,-1,-1>,<15,1,1> // A box shape
    pigment {
      object {
        text {ttf MagnetFont,SouthLtr,3,0 // ... with letter for "south" on it
          scale 2 translate <3.2,-.7,-1.5>
          }
        color rgb .85
        color rgb <1,0,0>
        }
      }
    finish {ambient .4}
    no_shadow
    no_reflection
    }
  }

#declare SampleShape=box{<-1,-.4,-.6>,<1,.4,.6>}  // Shape of samples

// Demonstration of "ordinary" ferromagnetic
// sample in the top half of the image:
#object {MagnetPair translate <0,2,0>}  // Magnets

#object {SampleShape  // Leftmost sample object
  rotate <100,15,0>   // "Turn and tumble" it
  pigment {           // Apply color gradient to
    gradient x        // indicate presence of
    color_map {       // magnetic poles
      [0 color rgb .75]
      [1 color rgb <.75,.25,.25>]      
      }
    scale 2.3
    translate <-1.15,0,0>
    }
  finish {ambient .4} // To slightly "flatten" shadows 
  translate <-1,2,0>   // Move to position
  }

#object {SampleShape    // Rightmost sample object
  rotate <-120,-30,90>  // "Turn and tumble" it
  pigment {             // Apply color gradient to
    gradient x          // indicate presence of
    color_map {         // magnetic poles
      [0 color rgb .75]
      [1 color rgb <.75,.25,.25>]      
      }
    scale 1.5
    translate <-.75,0,0>
    }
  finish {ambient .4} // To slightly "flatten" shadows 
  translate <1.5,2,0>   // Move to position
  }

// Demonstration of an orthomagnetic sample
// in the bottom half of the image:
#object {MagnetPair translate <0,-2,0>} // Magnets

#object {SampleShape  // Leftmost sample object
  rotate <100,15,0>   // "Turn and tumble" it
  pigment {
    object {  // Arrows to indicate orthomagnetism
      #object {ArrowSet rotate <100,15,0>}
      pigment {     // Apply color gradient
        gradient x  // to indicate presence
        color_map { // of magnetic poles
          [0 color rgb .75]
          [1 color rgb <.75,.25,.25>]      
          }
        scale 2.3
        translate <-1.15,0,0>
        }
      pigment {color rgb 0} // Color of arrows
      }
    }
  finish {ambient .4} // To slightly "flatten" shadows 
  translate <-1,-2,0> // Move to position
  }

#object {SampleShape    // Rightmost sample object  
  pigment {
    object {  // Arrows to indicare orthomagnetism
      #object {ArrowSet}
      pigment {color rgb .5}// No poles, so no color gradient!
      pigment {color rgb 0} // Color of arrows
      }
    }
  finish {ambient .4} // To slightly "flatten" shadows 
  rotate <-120,-30,90>
  translate <1.5,-2,0> // Move to position
  }

background {color rgb 1}  // White background

camera {  // Point of view:
    location <0,2,-8> // Seen from this location
    look_at <0,0,0>   // looking towards this location      
    }

// Illumination:
light_source {<20,10,-15> color rgb 1}
light_source {<-10,20,-10> color rgb 1}