I tried it to draw the trajectory of objects in three ways: First, in the main scene, this is the easiest, but there is a weak point, which is difficult to draw a trajectory of several objects. The second is to draw the trajectory of this animation in the sub-scene, and let the main scene control the moving three of this animation, in the main scene, click this animation, draw in the animation clip. The benefits of the latter two are the respective trajectories at the same time.
