Stupidly basic and ugly terrain generation for DragonRuby

terrain.rb

def tick args
  args.outputs.background_color = [0,0,0]
  args.outputs.labels << {x: 20, y: 700, text: "Landscape Test", r: 255, g: 255, b: 255 }

  args.pixel_array(:col).width = 1
  args.pixel_array(:col).height = 200
  px = args.pixel_array(:col).pixels
  200.times do |y|
    y = y.abs.floor & 0xff
    col = y << 8
    if y < 100
      col |= y
    end
    if y < 50
      col |= y << 16
    end
    if y < 10
      col = 0xffffff- (0x010101*(y)*10)
    end
    if y == 0
      col = 0x0
    end
    if y > 150
      col = 0xff8000
    end
    px[y] = 0xff000000 | col
  end

  $sprites = []

  cw = 8
  f = 0.6
  col = (1400/cw).floor

  $z = []
  srand(-1000)
  50.times do |y|
    xoff = Math.sin(y)*60+rand(30)-Math.sin(y/2.5+1.5)*20
    yoff = 0 #Math.sin(y*5)*10
    col.times do |c|
      x = c*cw*f
      h = Math.sin(x/50+y/5)*50 +
          Math.sin(y/40*3.14*2*x/256)*80 +
          Math.sin((x*2+y*10.2)/25+y/1.5)*20 +
          Math.sin((x+200)/100+ y/40)*50 +
          95 + rand(10)
      ty = h #(200 - h*2 + rand(5)).clamp(0,200)
      $sprites << {
        x: c*cw-xoff, y: 450-y*10-yoff, w: cw+4, h: h.abs.floor,
        tile_x: 0, tile_y: (200-ty).clamp(2,200), tile_w: 1,
        flip_vertically: false,
        tile_h: ty-h/5+rand(10), #+rand(20)+Math.sin(x/100+rand(2))/10,
        path: :col }
    end
  end
  args.outputs.labels << { x: 10, y: 30, text: $gtk.args.gtk.current_framerate.to_s, r: 255, g: 128, b: 128}
  args.outputs.background_color = [0,0,255]
  args.outputs.sprites << $sprites
end

You can consider this to be public domain, or under the MIT license, whichever you prefer and/or is valid where you are.