クヌース曲線

turtle_knuth_curve.rb

require 'oekaki'
require_relative 'turtle'

Width, Height = 600, 350

Oekaki.app width: Width, height: Height, title: "Knuth curve" do
  draw do
    clear
    
    t = Turtle.new(Width, Height, self)
    t.color(0xf0ff, 0xffff, 0xffff)
    t.move(250, -100)
    t.left(180)
    step = 8
    
    drawing = lambda do |depth, a, tn|
      if depth.zero?
        t.right(45 + tn)
        t.forward(step)
        t.left(45 + tn)
      else
        t.right(2 * tn + a)
        drawing[depth - 1, 2 * tn, -tn]
        t.right(45 - 3 * tn - a)
        t.forward(step)
        t.left(45 - tn + a)
        drawing[depth - 1, 0, -tn]
        t.right(a)
      end
    end
    
    drawing[9, -90, 45]
  end
end