pentaflake.rb

# frozen_string_literal: true

require 'picrate'

THETA = Math::PI * 2 / 5
SCALE_FACTOR = (3 - Math.sqrt(5)) / 2
MARGIN = 40
class PentagonSketch < Processing::App
  attr_reader :center, :pentagons, :radius
  def settings
    size(800, 800)
  end

  def setup
    sketch_title 'Pentagon'
    radius = width / 2 - 2 * MARGIN
    center = Vec2D.new(radius - 2 * MARGIN, radius - 6 * MARGIN)
    pentaflake = Pentaflake.new(center, radius, 4)
    @pentagons = pentaflake.pentagons
  end

  def draw
    background(255)
    stroke(0)
    pentagons.each do |penta|
      draw_pentagon(penta)
    end
    no_loop
  end

  def draw_pentagon(pent)
    points = pent.vertices
    begin_shape
    points.each do |pnt|
      pnt.to_vertex(renderer)
    end
    end_shape(CLOSE)
  end

  def renderer
    @renderer ||= GfxRender.new(g)
  end
end

PentagonSketch.new

class Pentaflake
  attr_reader :pentagons

  def initialize(center, radius, depth)
    @pentagons = []
    create_pentagons(center, radius, depth)
  end

  def create_pentagons(center, radius, depth)
    if depth.zero?
      pentagons << Pentagon.new(center, radius)
    else
      radius *= SCALE_FACTOR
      distance = radius * Math.sin(THETA) * 2
      (0..4).each do |idx|
        x = center.x + Math.cos(idx * THETA) * radius * Math.sin(THETA) * 2
        y = center.y + Math.sin(idx * THETA) * radius * Math.sin(THETA) * 2
        center = Vec2D.new(x, y)
        create_pentagons(center, radius, depth - 1)
      end
    end
  end
end

class Pentagon
  attr_reader :center, :radius

  def initialize(center, radius)
    @center = center
    @radius = radius
  end

  def vertices
    (0..4).map do |idx|
      center + Vec2D.new(radius * Math.sin(THETA * idx), radius * Math.cos(THETA * idx))
    end
  end
end