[Michael Szalapski]

Glad I could help! 🙂

– The Great Szalam
(The \’Great\’ stands for \’Not So Great, in fact, Extremely Humble\’)

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.

[Michael Szalapski]

You’re welcome. 🙂

– The Great Szalam
(The \’Great\’ stands for \’Not So Great, in fact, Extremely Humble\’)

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.

[Michael Szalapski]

Duplicate your running character.
Blur it.
Use levels on the alpha channel to crush it to wider than it originally was.
Use the Vegas effect to stroke the alpha. (Adjust the settings in the Vegas effect so you only have one line and full opacity on the whole thing instead of the default bunch of dotted fading lines.)

– The Great Szalam
(The \’Great\’ stands for \’Not So Great, in fact, Extremely Humble\’)

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.

[Michael Szalapski]

Does your script convert position keyframes to be relative to the new position after it’s run?

– The Great Szalam
(The \’Great\’ stands for \’Not So Great, in fact, Extremely Humble\’)

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.

[Michael Szalapski]

There are a number of solutions to this.
You could follow the regular solutions to the write-on effect. That is, to make another layer be a track matte for that layer. How you make it is up to you, but you could use a path with a stroke for example. The only tricky parts of this is making sure the width of the stroke fits properly in parts where it overlaps.

You could animate the shape itself. That is, make a keyframe for the path shape where it is fully there, go back in time and shrink the shape so that it’s down to nothing. Now, with a shape that loops like yours, you’d really need to think in steps and move backward to the first step, then the next, then the next instead of going straight to there being no shape.

An alternate method is a third-party script like Curva which animates the path for you: https://videohive.net/item/curva-script-premium-after-effects-script/8694469

– The Great Szalam
(The \’Great\’ stands for \’Not So Great, in fact, Extremely Humble\’)

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.

[Michael Szalapski]

You have two solutions.

1. Turn your composition panel from full resolution to Auto

2. Turn off the “Use hardware to accelerate…panels” in the preferences.

– The Great Szalam
(The \’Great\’ stands for \’Not So Great, in fact, Extremely Humble\’)

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.

[Michael Szalapski]

Is this a set you’ve built or is it in an actual building? This would be a LOT easier if you’re going to build it. My plan would be to build the back wall behind you with, ideally, a matching camera move in reverse. If not, you can try to rebuild it with a bunch of photos and kind of track it in to match and then rotoscope out the talent.

An even better alternate would be to angle the mirror so that you can still see the talent looking at themselves, but what’s behind them in the mirror is above, below, or to the side of where the camera goes.

– The Great Szalam
(The \’Great\’ stands for \’Not So Great, in fact, Extremely Humble\’)

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.

[Michael Szalapski]

It’s very close to one of the presets that ship with Particular (from Red Giant).

– The Great Szalam
(The \’Great\’ stands for \’Not So Great, in fact, Extremely Humble\’)

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.

[Michael Szalapski]

You don’t need to do that trick with Particular. With Particular, you can choose a layer as an “obscuration layer” and it will automatically composite the particles around it.
See this tutorial from Red Giant: https://www.redgiant.com/tutorial/episode-15-better-compositing-with-particles/

– The Great Szalam
(The \’Great\’ stands for \’Not So Great, in fact, Extremely Humble\’)

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.

[Michael Szalapski]

You could parent that layer to a null object, parent that null object to the camera, zero out the null’s coordinates and then move it in z (and scale it) as needed.

– The Great Szalam
(The \’Great\’ stands for \’Not So Great, in fact, Extremely Humble\’)

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.