Polygonal Flower Code

flower.rb

class Particle
  attr_accessor :x, :y
  attr_accessor :fx, :fy
  attr_accessor :history
  attr_accessor :lifespan

  def initialize x, y
    @x = x
    @y = y

    @lifespan = 255

    @history = []

    a = random 0, TwoPi
    k = 2
    @fx = k * cos(a)
    @fy = k * sin(a)
  end

  def update
    @x += @fx
    @y += @fy

    @lifespan -= 2

    history << Particle.new(@x, @y)
    history.shift if history.length > 200

    @fx *= 0.99
    @fy *= 0.99
  end
end

particles = []

setup do
  size 420
  # smoothing true
  line_width 4
  alpha_blending true
  title "Polygonal Flower"
  particles << Particle.new(width/2, height/2)
  particles << Particle.new(width/2, height/2)
  background 0
  framerate 60
end

update do
  particles << Particle.new(width/2, height/2)
  particles.each do |p|
    p.update
  end

  particles = particles.reject { |p| p.lifespan < 5 }
end

draw do
  particles.each_cons(2) do |a, b|
    min_history = [a.history.length, b.history.length].min
    for i in 0..min_history-1
      k = 240
      p = i / min_history.to_f
      color k, k*p, k, a.lifespan*p
      line a.history[i].x, a.history[i].y, b.history[i].x, b.history[i].y
    end
  end
end