screensaver [OpenComputers]

local gpu, r, xr, ti = require("component").gpu, math.random, bit32.bxor, table.insert
local tbl, tbl1, S, gsF, gsB, w, h, n, c, Fc, Bc, C, D, i, j, m, k, q, p, a, b = {}, {x = {}, y = {}}, "▄", gpu.setForeground, gpu.setBackground, gpu.getResolution()
local t = (w-h*2)/2
local function pix(x, y, color)
  n = y%2
  y = (y+n)/2
  c, Fc, Bc = gpu.get(x+t, y)
  if c ~= S then
    Fc = Bc
  end
  if n == 0 then
    Fc = color
  else
    Bc = color
  end
  gsF(Fc)
  gsB(Bc)
  gpu.set(x+t, y, S)
end

gsB(0)
gpu.fill(1, 1, w, h, " ")
for i = 1, h do
  tbl[i] = {}
  for j = 1, h do
    ti(tbl1.x, i)
    ti(tbl1.y, j)
  end
end
for n = 1, #tbl1.x do
  k = r(n)
  tbl1.x[n], tbl1.x[k], tbl1.y[n], tbl1.y[k] =
  tbl1.x[k], tbl1.x[n], tbl1.y[k], tbl1.y[n]
end
while true do
  for i = 1, h do
    for j = 1, h do
      tbl[i][j] = 0
    end
  end
  for i = 1, h do
    m = r(0, 1)
    tbl[i][1], tbl[1][i] = m, m
  end
  C, D, i, j = r(0, 255), t
  for y = 2, #tbl do
    for x = y, #tbl[y] do
      q = xr(tbl[x-1][y], tbl[x][y-1])
      tbl[x][y], tbl[y][x] = q, q
    end
  end
  for o = 1, #tbl1.x do
    i, j = tbl1.x[o], tbl1.y[o]
    p, a, b = i*j*C, -j+h*2, -i+h*2
    if tbl[i][j] == 1 then
      pix(j, i, p)
      pix(a, b, p)
      pix(a, i, p)
      pix(j, b, p)
    else
      pix(j, i, 0)
      pix(a, b, 0)
      pix(a, i, 0)
      pix(j, b, 0)
    end
    pix(r(-D+1, 0), r(1, h*2), C)
    pix(r(h*2, w-D), r(1, h*2), C)
  end
  gsF(65280)
  gsB(0)
  os.sleep(2)
end