PICO-8 source code to create traveling circles using sine wave.

circletravel.lua

r=64
function _draw()
	cls(7)
	circfill(r,r,r,0)
	
	num=10
	speed=0.3
	rad=5
	seq=0.5
	
	pos={}
	for i=0,num do
		x=cos(i/(num+1)*0.5)*r
		y=sin(i/(num+1)*0.5)*r
		line(r-x,r-y,r+x,r+y,5)
		pos[i]={x=x,y=y}
	end
	
	for i=0,num do
		p=pos[i]
		offset=i/(num+1)*seq
		v=sin(time()*speed+offset)
		nx=p["x"]*v
		ny=p["y"]*v
		rm=1--abs(v)
		circfill(nx+r,ny+r,rad*rm,7)
	end
end