Undulating Waves

undulating_waves.rb

# video @ https://vimeo.com/218743733
require 'graphics'

class Waves < Graphics::Simulation
  include Math

  def initialize
    super 600, 600, 24
    self.color.default_proc = -> h, k { k }
  end

  def draw(t)
    # clear
    num_lines.times.map do |i|
      relative_t = t/5.0+i
      offset     = i*segment_len + segment_len/2
      freq       = 0.1/1.75
      ø          = 2*Math::PI*i/num_lines.pred+t*freq
      color1     = [c(ø),      c(ø+PI/2), c(-ø)]
      color2     = [c(ø+PI/2), c(ø),      c(-ø)]
      horizontal_line relative_t,     freq, offset, color1.map { |n| n/2 }, color1
      vertical_line   relative_t*0.8, freq, offset, color2.map { |n| n/2 }, color2
    end
  end

  def c(ø)
    sin(ø/2+0.5).+(1)./(2).*(255).to_i
  end

  def num_lines
    @num_lines ||= 20
  end

  def segment_len
    @segment_len ||= h/num_lines
  end

  def horizontal_line(t, freq, y_base, color1, color2)
    pairs(t, freq, y_base).each do |(x1, y1), (x2, y2)|
      line x1, y1-3, x2, y2-3, color1
      line x1, y1,   x2, y2,   color2
      line x1, y1+3, x2, y2+3, color1
    end
  end

  def vertical_line(t, freq, x_base, color1, color2)
    pairs(t, freq, x_base).each do |(y1, x1), (y2, x2)|
      line x1-3, y1, x2-3, y2, color1
      line x1,   y1,   x2, y2, color2
      line x1+3, y1, x2+3, y2, color1
    end
  end

  def pairs(t, freq, base)
    num_lines.succ.succ.times.map do |i|
      val1 = segment_len*i - segment_len/2
      val2 = base + segment_len*sin(2*PI*(t+i)*freq)/2
      [val1, val2]
    end.each_cons(2)
  end
end

Waves.new.run

looks like a broke this one. You are the only person to find the array as color thing and it was removed.

I did a horrible thing and changed your default_proc to create and register the color properly. It doesn't quite work until the first full undulation is done, but then it looks fine (?):