Bayer dithering in PICO-8

bayer.lua

-- https://www.lexaloffle.com/dl/docs/pico-8_manual.html#FILLP

local dither={
 0b0000000000000000,
 0b1000000000000000,
 0b1000000000100000,
 0b1010000000100000,
 0b1010000010100000,
 0b1010010010100000,
 0b1010010010100001,
 0b1010010110100001,
 0b1010010110100101,
 0b1110010110100101,
 0b1110010110110101,
 0b1111010110110101,
 0b1111010111110101,
 0b1111110111110101,
 0b1111110111110111,
 0b1111111111110111,
 0b1111111111111111,
}

local p=0
local col1=0
local col2=1

function _draw()
  cls()
  p+=1
  if p%17==0 then
    col1+=1
    col2+=1
  end
  col1=col1%16
  col2=col2%16

  local col=(col2<<4)|col1

  fillp(dither[p%17])
  rectfill(16,16,32,32,col)

  for l=0,128 do
    fillp(dither[(l/(120/16))\1+1])
    line(40,l,56,l,col)
  end
end