// Last edited on 2011-04-27 22:54:19 by stolfi
// CUTTERS

#macro cutter_not_NE()
  // A cutter that removes the Northeast quarter of threespace, rel to Z axis.
  union{
    plane{ x,0 }
    plane{ y,0 }
  }
#end

#macro cutter_not_SE()
  // A cutter that removes the Southeast quarter of threespace, rel to Z axis.
  union{
    plane{ x,0 }
    plane{ -y,0 }
  }
#end

#macro cutter_not_SEZ()
  // A cutter that removes the upper half of the Southeast quarter of
  // threespace, rel to origin.
  union{
    plane{ x,0 }
    plane{ -y,0 }
    plane{ z,0 }
  }
#end

#macro cutter_not_E()
  // A cutter that removes the East half of threespace, rel to Z axis.
  plane{ +x,0 }
#end

#macro cutter_not_N()
  // A cutter that removes the North quarter of threespace, rel to Z axis.
  plane{ +y,0 }
#end

#macro cutter_not_S()
  // A cutter that removes the South quarter of threespace, rel to Z axis.
  plane{ -y,0 }
#end

#macro cutter_not_Z()
  // A cutter that removes the positive Z halfspace
  plane{ +z,0 }
#end

#macro cutter_NS_slice()
  // A cutter that leaves only a slice of space along the {X=0} plane.
  intersection{
    plane{ +x,0 translate +0.005*x }
    plane{ -x,0 translate -0.005*x }
  }
#end

#macro cutter_EW_slice()
  // A cutter that leaves only a slice of space along the {Y=0} plane.
  intersection{
    plane{ +y,0 translate +0.005*y }
    plane{ -y,0 translate -0.005*y }
  }
#end

#macro cutter_hor_slice()
  // A cutter that leaves only a slice of space along the {Z=0} plane.
  intersection{
    plane{ +z,0 translate +0.005*z }
    plane{ -z,0 translate -0.005*z }
  }
#end

#macro cutter_keep_all()
  // A cutter that does not remove anything:
  sphere{ <0,0,0>, 3000 }
#end