So basically if you use the bucket tool on an empty layer it covers the whole anim, but if you zoom out, it makes a perfect square. By repeating this and rotating the squares a bunch of times, you can get an octagon. You make perfect triangles by doing the same thing with making the square, but you rotate it 45 degrees and make it so that exactly one half of the square is shown. Use the bucket tool on the square, (and make it so that one half is the same as the background color) and you’ve basically got yourself a triangle. I believe you can figure out the rest from there.