1 The idea
When the main body stops, loose or hanging parts carry on and swing back (follow-through), and the parts don’t move together: the further from the root, the later they move (overlapping action). If every link moves at once, the antenna looks like a stiff rod.
A common animator’s method is offsetting: reuse the same swing, but delay each next link by a few frames. In comp the same trick works for several elements that should trail each other: debris, sparks or graphic layers.
2 Hands-on
Task: make the antenna tip peak exactly 6 frames after the root
There are 3 steps from root to tip, so the last link’s swing lags the root by 3 × the delay per link
3 Deep dive
Force travels from root to tip
When the robot head starts moving, the antenna root is pulled first while the tip stays behind through inertia, so it bends backwards (drag). When the head stops, the tip keeps going forward and swings back (follow-through). Each joint moves in turn, like a whip.
- 1Head starts
- 2Antenna leans back (drag)
- 3Head stops
- 4Tip carries on and swings
The offset method: quick and controllable
Instead of simulating the whole chain, make one swing for the root and copy it down the chain, delaying each next link by 1–3 frames. Further links can swing a little more. The tip lags the root by the number of steps × the delay.
| Delay per link (4 links) | Tip lag | Feel |
|---|---|---|
| 0 | 0 f | stiff rod |
| 1 | 3 f | slightly springy |
| 2 | 6 f | flexible, a clear wave |
| 4 | 12 f | rope- or tail-like |
In comp: elements that should trail
Several rocks from one blast, several spark passes, or layers of a HUD graphic: if they start on exactly the same frame they look like copies. Use TimeOffset to stagger them by a few frames, but never so far that they detach from their cause; debris must not fly before the blast.
Elements from one cause: never before it, never all on the same frame.
4 In real work
In Nuke
- TimeOffset: delay copies of an element by a few frames each.
- Transform: drive the next link’s rotate from the previous one, delayed, with an expression such as Transform1.rotate(frame-2).
- Build the chain child-first: rotate each link around its joint, Merge it onto its parent link, then put the parent’s Transform below that Merge so the rotations add up into a whip-like curve.
- Dope Sheet: stagger each layer’s keys into steps so the wave is easy to see.
Common mistakes → the fix
- ✗ Every part starts and stops together✓ Delay the outer parts a few frames each.
- ✗ So much delay the tip seems to move on its own✓ The tip must still read as caused by the root. Start at 1–2 frames per link.
- ✗ Follow-through swinging as long as the main move✓ Let it die away quickly so it doesn’t steal focus from the main action.
Before you send the shot
- Outer parts trail the root
- After the body stops, loose parts carry on and fade
- Elements from one cause don’t start on the same frame
- Nothing starts before its cause
5 Check yourself
A logo has 5 letters popping in at exactly the same time and it feels stiff. Simplest fix?
🔒 Answer the question above and this card opens
1. A 5-link antenna (4 steps) with 1.5 frames of delay per link. How far does the tip lag the root?
2. The robot head starts moving right. Which way should the antenna lean in the first frames?
Where the numbers come from: The root link is a damped spring (2 Hz, ζ = 0.18) pushed by the head’s acceleration, integrated with semi-implicit Euler at 192 steps per second. The other links replay the same swing, delayed. This is the animator’s offset method, not a full physics simulation of the chain. The thin antenna is deliberately underdamped (wobbly, as in M4’s table); in a real shot, raise damping so the swing dies away quickly.