Activator, Control, and Speed Tracks

Activator, Control, and Speed tracks share the same clock but resolve object state in a defined order.

These tracks change whether simulation runs, when an object restarts, and how much simulation time it consumes.

Activator Track

An Activator Track targets one FX object. The object is active while any Activator Clip covers the current time. Outside the clips it is inactive and neither ticks nor renders.

Since 2.2.9 Every object except the root has a saved Enabled switch in the Inspector. A disabled object stays off; an Activator Clip does not wake it.

Control Track

Control Clips target objects individually. Entering or switching to a Control Clip:

1. resets the target object;
2. recursively resets its FXObject children;
3. applies the clip seed or a fresh executor RNG seed;
4. activates/renders it for the clip range.

Control is suitable for sequencing several one-shot emitters on one lane or replaying the same subtree with deliberate seeds.

On Exit

Since 2.2.11

Cut on the left, Drain on the right: both clips end at 1.5 s.

On Exit, in the clip's Inspector or its right-click menu, decides what leaving a Control clip does to its object:

On Exit	Leaving the clip
Cut: vanish (default)	Stops and hides the object at once, as before 2.2.11.
Drain: fade out	The object starts nothing new, and what it shows, such as particles and trails, lives out its life. It keeps running until then and stops on its own. The end of a draining clip is shaded.

Entering a clip again while the object drains restarts it, which cuts the particles that were still fading. Nothing new starts inside an object that drains: a child's clip that begins meanwhile neither starts nor shows the child.

On Section Loop

Since 2.2.11

Auto on the left carries on through every loop; Restart on the right starts over on every pass.

Shown when the Timeline has sections. It decides what a Control clip that stays on across a section's loop, or across a jump, does to its object:

On Section Loop	At each loop or jump
Auto: carry on, restart if finished (default)	An object that still plays carries on, so a looping emitter never stutters. One that has finished restarts, so a one-shot burst plays on every pass.
Restart every pass	Restarts the object every time. A loop mark shows in the clip's corner.

Activator and Control Together

TimelineState.resolve considers whether each control type exists and whether it is active at the current time. Do not assume one simply overrides the other. Preview the exact combination; removing or muting a controlling track restores objects that are no longer controlled.

Speed Track

Speed Track samples a scalar and writes the target's selfTimeScale. Children inherit the hierarchical time scale.

Speed	Result
0	Freeze simulation while retaining the object.
0..1	Slow motion.
1	Normal tick rate.
>1	Multiple bounded simulation substeps per game tick.

The runtime limits substeps per tick to keep extreme values from creating unbounded work. Speeds beyond the cap cannot simulate arbitrary time in one tick.

Since 2.2.7 Java code can also change the speed of a whole runtime with FXRuntime#setRate, which scales the objects and the Timeline clock together. A Speed Track that targets the root wins over the rate for the ticks it covers. See FXRuntime Lifecycle.

FX Instances

Since 2.2.9

An FX instance plays its source's Timeline on its own clock. The outer tracks drive that clock like any object state:

• a Control clip that restarts the instance, or one of its parents, starts the clock at 0;
• an Activator Track that turns the instance off pauses the clock, and it continues when the instance turns on again;
• a Speed Track on the instance or a parent scales the clock.

When the outer Timeline and the source drive the same object and channel, the outer Timeline wins. See FX Instances for the full rules.

State Restoration

When a Speed Track is removed, muted, or rebound, the previously controlled object's scale returns to 1. Activator/Control state likewise returns to active and visible when the object is no longer controlled.

Parent targeting

Bind Control or Speed to an Empty parent when the whole child effect should restart or change speed together.