buffer pixel array data to persist across ticks

main.rb

# buffer pixel array data to persist across ticks

def tick args
  dimension = 100  # keep it small and let the GPU scale it when rendering the sprite.

  if args.tick_count.zero?
    # Set up our "parray" pixel array and fill it with black pixels.
    args.pixel_array(:parray).width = dimension
    args.pixel_array(:parray).height = dimension
    args.pixel_array(:parray).pixels.fill(0xFFFFFFFF, 0, dimension * dimension)  # black, full alpha

    # This variable persists the pixel data
    # You can create it directly - you don't need to make the pixel array above
    # I'm just demonstrating that, if you already have the array created, keep a copy
    # Note that .dup doesn't seem to be needed
    $pixel_buffer = args.pixel_array(:parray).pixels
  end

  # Modify the pixel buffer
  random_pixel = rand(dimension * dimension)
  random_color = rand(0xFFFFFFFF)
  $pixel_buffer[random_pixel] = random_color

  # effectively make a new pixel array with the same name each tick
  # and fill it with your pixel buffer data
  args.pixel_array(:parray).width = dimension
  args.pixel_array(:parray).height = dimension
  args.pixel_array(:parray).pixels = $pixel_buffer

  # output the pixel array
  args.outputs.primitives << [590, 310, dimension * 4, dimension * 4, :parray].sprite
  args.outputs.primitives << args.gtk.current_framerate_primitives
end