A Simple Turtle Graphics Implementation in Clojure

Turtle graphics is a popular way for introducing programming to kids. It was part of the original Logo programming language developed by Wally Feurzig and Seymour Papert in 1966. Turtle, originally a robotic creature moves on the floor. It takes commands relative to its own position, such as "move forward 10 steps" and "turn left 90 degrees". Turtle also has a pen which may be lowered to the floor so that a trace is left of where it has traveled.

turtle.clj

 (defn fib [turtle depth]
   (forward turtle 30)
   (if (> depth 2)
     (do 
       (left turtle 15)
       (fib turtle (- depth 1))
       (right turtle 30)
       (fib turtle (- depth 2))
       (left turtle 15)))
   (back turtle 30))

 (let [turtle (turtle 400 400)]
   (pen-up turtle)
   (go turtle 0 -100)
   (pen-down turtle)
   (fib turtle 10)
   (show turtle))

fern

 (defn fern [turtle size]
   (if (> size 4)
     (do 
       (forward turtle  (/ size 25))
       (left turtle 90) (fern turtle (* size 0.3))
       (right turtle 90)
       (right turtle 90) (fern turtle (* size 0.3))
       (left turtle 90)  (fern turtle (* size 0.85))
       (back turtle (/ size 25)))))

 (let [turtle (turtle 400 400)] 
   (pen-up turtle)
   (go turtle 0 -200)
   (pen-down turtle)
   (pen-color turtle Color/green)
   (fern turtle 1500)
   (write turtle "test.png"))

tree

Tags: clojure graphics