require "bitmap"

-- Signifies the white edges on the blue squares.
local LT = 0
local TR = 1
local RB = 2
local BL = 3

local edges = {
    {LT, BL, BL, RB, RB, TR, TR, LT, LT, BL, BL, RB},
    {LT, LT, BL, BL, RB, RB, TR, TR, LT, LT, BL, BL},
    {TR, LT, LT, BL, BL, RB, RB, TR, TR, LT, LT, BL},
    {TR, TR, LT, LT, BL, BL, RB, RB, TR, TR, LT, LT},
    {RB, TR, TR, LT, LT, BL, BL, RB, RB, TR, TR, LT},
    {RB, RB, TR, TR, LT, LT, BL, BL, RB, RB, TR, TR},
    {BL, RB, RB, TR, TR, LT, LT, BL, BL, RB, RB, TR},
    {BL, BL, RB, RB, TR, TR, LT, LT, BL, BL, RB, RB},
    {LT, BL, BL, RB, RB, TR, TR, LT, LT, BL, BL, RB},
    {LT, LT, BL, BL, RB, RB, TR, TR, LT, LT, BL, BL},
    {TR, LT, LT, BL, BL, RB, RB, TR, TR, LT, LT, BL},
    {TR, TR, LT, LT, BL, BL, RB, RB, TR, TR, LT, LT}
}

local light_olive = bitmap.rgbColor(0xd3, 0xd0, 0x04)
local pale_blue   = bitmap.rgbColor(0x32, 0x50, 0xff)

local W = color.white
local B = color.black

local colors = {
    {W, B, B, W},
    {W, W, B, B},
    {B, W, W, B},
    {B, B, W, W}
}

local bmp = bitmap.of(1000, 1000, light_olive, "Peripheral_drift_illusion")

local function draw_edge(px, py, edge)
    local c = colors[edge + 1]
    bmp:line(px, py, px + 46, py, c[1], 4)
    bmp:line(px + 46, py, px + 46, py + 46, c[2], 4)
    bmp:line(px, py + 46, px + 46, py + 46, c[3], 4)
    bmp:line(px, py + 46, px, py, c[4], 4)
end

for x = 0, 11 do
    local px = 90 + x * 70
    for y = 0, 11 do
        local py = 90 + y * 70
        bmp:rectangle(px, py, 50, 50, pale_blue)
        draw_edge(px, py, edges[y + 1][x + 1])
    end
end
bmp:view(false, "", "", true)