格子曲線

turtle_grate_curve.rb

require 'oekaki'
require_relative 'turtle'

Width, Height = 400, 400

Oekaki.app width: Width, height: Height, title: "Grate curve" do
  draw do
    clear(color(0xffff, 0x7dff, 0))
    
    t = Turtle.new(Width, Height, self)
    t.color(0, 0, 0)
    t.move(-160, 150)
    
    two = lambda do |a, c, w|
      return if c <= 1
      t.right(a)
      t.forward(1)
      t.right(a)
      t.forward(w)
      t.left(a)
      t.forward(1) if c > 1
      t.left(a)
      t.forward(w)
      two[a, c - 2, w]
    end
    
    square = lambda do |a, h, w|
      t.forward(w)
      two[a, h - 1, w]
    end
    
    grate = lambda do |n, a, w, h|
      if n.zero?
        square[a, h, w]
      else
        t.right(a)
        grate[n - 1, -a, h / 4, w]
        t.forward(h / 8)
        grate[n - 1,  a, h / 4, w]
        t.forward(h / 8)
        grate[n - 1, -a, h / 4, w]
        t.left(a)
      end
    end
    
    grate[4, 90, 320, 320]
  end
end