Writhing Electric Bezier

writhing_electric_bezier.rb

# Video @ https://twitter.com/josh_cheek/status/832083163220475905

# You might need to already understand how bezier curves work to understand this.
# This one is probably a reasonable way to explore it:
# https://gist.github.com/JoshCheek/9139ff5f2764493a69675268e5e9556d
require "graphics"

class Integer
  def of(obj)
    times.map { obj }
  end
end

class WritingElectricBezier < Graphics::Simulation
  def initialize
    super 500, 500*9/16, 24
    @derivations = 100 # in the calc sense
    @length      = 75  # how many points our line should have
    @points      = (@derivations + @length).times.map { rand_point }
    color.default_proc = -> h, k { k }  # so we don't have to rely on named colours

    # Put white in there more times so since it has the most "electrifying" feel
    @vibrant_colors = [:red, :green, :blue, :cyan, :magenta, :yellow, :black, *5.of(:white)]
  end

  def draw(iteration)
    clear

    # randomly swap out some of the points so the lines change across frames
    rand(10).times do
      idx = rand(@points.length)
      @points[idx] = rand_point
    end

    # how many lines to draw
    rand(8).times do |line_i|
      # random distance along the bezier, leads to lines that are nearby but different
      percentage = 0.5 + rand(-0.3..0.3)

      # "derive" aka run out the iterations along the bezier curve
      points = @derivations.times.reduce @points do |pts,*|
        percentages_between pts, percentage
      end

      if line_i.zero?
        # first line gets drawn thick and in one of the vibrant colors with
        # a higher probability of being white
        color = @vibrant_colors.sample
        draw_lines_between points, color
        next unless color == :white
        draw_lines_between points.map { |x, y| [x-2, y] }, color
        draw_lines_between points.map { |x, y| [x+1, y] }, color
        draw_lines_between points.map { |x, y| [x, y-2] }, color
        draw_lines_between points.map { |x, y| [x, y+1] }, color
      else
        # the rest of the lines are thinner and can appear anywhere on the color spectrum
        draw_lines_between points, [rand(255), rand(255), rand(255)]
      end
    end
  end

  def draw_lines_between(points, color)
    points.each_cons 2 do |(x1, y1), (x2, y2)|
      line x1, y1, x2, y2, color
    end
  end

  # feels like if I think about calculus for a little bit, I might be able to
  # come up with an equation for htis so that we don't have to repeatedly invoke it
  def percentages_between(points, percent)
    points.each_cons(2).map do |(x1, y1), (x2, y2)|
      [x1+(x2-x1)*percent, y1+(y2-y1)*percent]
    end
  end

  def rand_point
    [rand(3*w)-w, rand(3*h)-h]
  end
end

WritingElectricBezier.new.run