Use the time rather than the count

import scene from math import sin, pi class MyScene (scene.Scene): def update(self): scene.translate(self.size.w/2, self.size.h/2) freq = 15.2 weight = (1+sin(2*pi*freq*self.t))/2 scene.fill((weight,weight,weight)) scene.rect(-80, -80, 160, 160) scene.run(MyScene(),show_fps=True,frame_interval=1)