PICO-8 source code to create animated spiral.

spiral.lua

r=64
t=0
function _draw()
	cls(1)
	for n=0,6,1 do
		for i=0,100,1 do
			ang=3.1415/180.0*2
			x1=cos((i+t)*ang)*i+r
			y1=sin((i+t)*ang)*i+r
			x2=cos((i+1+t)*ang)*(i+1)+r
			y2=sin((i+1+t)*ang)*(i+1)+r
			col=9
			if n<3 then
				col=4
			end
			line(x1+n,y1,x2+n,y2,col)
		end
	end
	t+=1
end