require "bitmap"

local bmp

local function sierpinski_triangle(level, x, y, size)
    if level > 0 then
        local col = color.black
        bmp:triangle(x, y, x + size, y, x, y + size, col, 1)
        local size2 = size // 2
        sierpinski_triangle(level - 1, x, y, size2)
        sierpinski_triangle(level - 1, x + size2, y, size2)
        sierpinski_triangle(level - 1, x, y + size2, size2)
    end
end

local size <const>  = 800
local level = 8
bmp = bitmap.of(size, size, color.white, "Sierpinski Triangle")
sierpinski_triangle(level, 20, 20, size - 40)
bmp:view()