タートルグラフィックス

turtle.rb

class Turtle
  def initialize(width, height, ob)
    @width, @height = width, height
    @pen_po = Vector[0, 0]
    @pen = ob
    @dir = Vector[1, 0]
    @color = [65535, 65535, 65535]
  end
  attr_accessor :pen_po, :dir
  
  def left(deg)
    θ = PI * deg / 180
    @dir = Matrix[[cos(θ), -sin(θ)], [sin(θ), cos(θ)]] * @dir
  end
  
  def right(deg)
    left(-deg)
  end
  
  def forward(length, draw = true)
    next_po = @pen_po + @dir * length
    if draw
      @pen.color(*@color)
      @pen.line(@width / 2 + next_po[0], @height / 2 - next_po[1],
         @width / 2 + @pen_po[0], @height / 2 - @pen_po[1])
    end
    @pen_po = next_po
  end
  
  def back(length)
    forward(-length, false)
  end
  
  def color(r, g, b)
    @color = [r, g, b]
    @pen.color(*@color)
  end
  
  def circle(radius, fill = false)
    @pen.color(*@color)
    @pen.circle(fill, @width / 2 + @pen_po[0], @height / 2 - @pen_po[1], radius)
  end
  
  def move(x, y)
    @pen_po = Vector[x, y]
  end
end