UGTK / Toolkit / Component Module / Ping Pong Movement Component Completed

PingPong Movement Component

Summary

The PingPong Movement Component makes an object travel back and forth between two points, forever: a moving platform, a patrolling guard, a lift, a hazard sweeping across a corridor.

It is not a new behaviour but a composition: a Follow component moves the object, and a small state machine swaps the target between the two endpoints every time one is reached. Everything is already wired in the two shipped prefabs — there is no ping-pong script to add.

Modules Dependencies

Follow System: performs the actual movement towards each endpoint.
StateMachine: holds the "going to A" / "going to B" states and flips between them.
Pooling System: used by the prefabs to recycle the moving objects.
Event System: carries the "endpoint reached" notification that drives the state change.

Carried inside the prefabs. These modules are not referenced by the assembly definition - the components are simply already attached to the prefabs this module ships. Remove one of them from the project and the prefab keeps its layout and loses that behaviour, with nothing in the console to say so.

Module	Component, and the prefab carrying it
`UtilitySystems/ActivationSystem`	`Mn_GameObjectActivation` (in `PingPong2DObject`), `Mn_GameObjectActivation` (in `PingPong3DObject`)

Setup

Drop PingPong2DObject or PingPong3DObject into the scene — pick the 3D one for objects in the world, the 2D one for UI (see the note on spaces in the Follow System documentation):

Then assign the two endpoints and configure the follow settings — speed, curve, stop distance and tolerance all come from the Follow component.

How To Use

Everything is configured on the child Follow component; the ping-pong itself has no options of its own. The settings that matter for this use:

Speed and Movement Curve — a linear curve gives a constant sweep (a conveyor), an ease-in-out curve gives the pendulum feel of a lift slowing down at each end.
Curve Mode Distance makes each leg take the same time regardless of the gap between the two points: use it when several platforms must stay in sync.
Tolerance decides when an endpoint counts as reached, and therefore when the direction flips. Too small and the object jitters at the ends without turning around.

Good to know:

Mn_PingPongMovementComponent is an empty placeholder. Adding it to a GameObject does nothing at all; the behaviour lives in the prefabs. Use the prefabs.
The object that moves is the Follow component's Owner, that is its parent — the same rule as the whole Component Module.
The endpoints are transforms in the scene, not offsets: moving the parent of the platform moves the endpoints too, which is usually what you want, but it means a prefab dropped in a new scene needs its endpoints assigned again.

Testing Scene

Open PingPongScene in Debug/. It holds PingPong3DObject between the two endpoint markers (WallA, WallB) plus a Canvas. Press play: the object travels to one endpoint, turns round, and comes back, indefinitely.

What to check, in order:

Press play and watch at least two full round trips. One is not enough — see below.
Select 3DFollowComponentA and 3DFollowComponentB in the hierarchy and watch them switch on and off in turn as the state machine changes state.
Clear the target on one of the follow components and play again: the console warns that the follow is heading for (0,0,0).

Why two round trips and not one. Until 2026-08-03 this scene did not animate at all, and the reason is worth knowing because it applies to any component driven by being switched on and off: Mn_FollowComponent started following from Start(), and Unity runs Start once, the first time an object becomes active. A ping-pong alternates two follow objects forever, so from the second activation onwards nothing restarted the movement. Raising startFollowingOnStart on its own could never have fixed it. The component now also restarts on OnEnable, guarded so the first activation is still handled by Start and the original ordering is unchanged.

Technical Info

Path	Content
`Prefabs/PingPong2DObject.prefab`	Ready-made composition for UI space
`Prefabs/PingPong3DObject.prefab`	Ready-made composition for world space
`Scripts/Mn_PingPongMovementComponent.cs`	Empty placeholder kept for backwards compatibility: no logic
`Debug/PingPongScene.unity`	Test scene