// Persistence Of Vision Ray Tracer POV-Ray 3.5 sample Scene
// by Chris Young
// MACRO2.POV demonstrates basic use of a macro to modify an
// identifier parameter, not just do something based upon the
// parameter.  Defines a macro called Turn_Me which takes
// an object identifier and re-declares it turned a specified
// amount about a particular axis. The result is passed back
// through the parameter.

#include "colors.inc"

light_source { <1000,1000,-1000>, White}

camera { location <3,3,-10> direction 2*z look_at <0,0,0>}

union {
 plane{y,-2} plane{-z,-10} plane{x,-10}
 pigment{checker Cyan,Yellow}
}

// Define the macro.  Parameters are:
//   Stuff:    The stuff to be rotated.  This identifier is
//             actually re-declared and the new object is passed
//             back to the calling module.
//   Degrees:  Number of degrees to rotate
//   Axis:     The axis about which we'll rotate
#macro Turn_Me(Stuff,Degrees,Axis)
    #declare Stuff=object{Stuff rotate Axis*Degrees}
#end

#declare Thing = cone{0,1/2,y,0}

object{Thing               // Display the original Thing
  pigment{rgb<1,0,0>}
  translate -2.25*x
}

Turn_Me(Thing,-90,x)       // Turn -90 about x

object{Thing               // Thing was changed by Turn_Me
  pigment{rgb<0,1,1>}
}

Turn_Me(Thing,-90,y)       // Turn -90 about y

object{Thing               // Thing was changed again
  pigment{rgb<1,1,0>}
  translate 2.25*x
}

