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view/download model file: logo.nlogo

WHAT IS IT?

Imitation of early Logo turtle graphics.
Written in NetLogo 4.1.3 by Ralph Abraham 2/1/12.

CREDITS AND REFERENCES

Thanks to Papert and Abelson.

PROCEDURES

;;; logo.nlogo, drawing with one turtle

to setup
  ca    ;;; c,lear all
  crt 1 ;;; create turtle 0
    [ set heading 0 ;;; due north
      set size 3 ;;; more visible
      set color red ;;; just for a start
    ]
end

to step
  ask turtle 0 [ fd 1 ] ;;; jump ahead one patch size
end

to drop-pen
  ask turtle 0 [ pd ] ;;; pen down
end

to raise-pen
  ask turtle 0 [ pu ] ;;; pen up
end

to rotate-cw ;;; clockwise by 15 debrees
  ask turtle 0 [ set heading ( heading + 15 ) ] ;;; increment heading
end

to rotate-ccw ;;; counter clockwise by 15 debrees
  ask turtle 0 [ set heading ( heading - 15 ) ] ;;; increment heading
end


;;; end of code