Add arrowhead to shape layer using trim paths & expressions?

[Guest]

Hi,

I am trying to use expressions to attach an arrowhead to a shape layer.

I'm using the 'trim paths' effect on the shape layer to grow a stroke over time (using the start/end/offset features).

I would like to attach an arrowhead to the tip of the stroke, using an expression to animate it dynamically (e.g. the arrowhead follows the stroke when animated using the start/end/offset values)

I've attached a basic project file if anyone can help?

94_shapelayerarrowhead.zip

Thanks for your time, any help appreciated

Tim

[Rick Gerard]

The easiest way to do this is to use a stroked path to reveal the shape layer, then copy and paste the path to the position property of the arrowhead. Auto orient the arrowhead to the path and adjust the timing of both the stroke and the arrowhead position to match them up.

Using trim path makes it more difficult to adjust timing than using start and end for stroke and I can't think of an automatic way to match the timing with an expression.

Another option would be to pre-compose your arrowhead layer after you've used the path for position, then use time remapping to adjust the timing. This may be the easiest solution if you have a lot of timing changes to follow.

[Fyin.com]

How do you reveal the shape layer with a stroked path?

[Fyin.com]

I realize this is an old thread, but I stumbled upon a very nice tutorial if anyone is still looking to master this technique:

http://www.monologue.gr/tutorials/an-animated-arrow-tutorial-to-rule-them-all/

[Mylenium]

Yupp, as Rick said, use a motion path and adjust the timing. There is no way to measure the exact length of mask and shape layer paths, so there is no easy way to correlate them with the percentages of the Trim Paths modifier. Once it's a motion path, one could derive that info using integration functions based on the positional differences of the current keyframe to the next (n, n+1), but that seems unnecessary and can considerably slow things down, as it would have to be done in a loop. I think Dan Ebberts has such a setup on his site motionscript.com, if you're still interested in doing it that way.

Mylenium

[modio]

Hi there,

We've been working on a script that automates this process. With the click of a button, you'll be able to attach an arrowhead (or any shape) to the front and end of a stroke along your mask path. I think you'll find it useful.

Check out the video to see how it works: https://modio.tv/downloads/easy-arrows/

Cheers!

[Liran Tabib]

You can paste the shape path to the position of the ArrowHead Layers, and with valueAtTime() expression or valueAtKey(), to create the right movement. After Effects native Auto-Orient, don't work so well with two movement directions so you'll have to use expressions to overcome that.

Alternatively you can use ArrowHead Script that was created exactly for that:

http://www.vdodna.com/products/arrowhead/

Regards!

[Mike_Abbott]

or use BAO BOA... 

[Szalam]

Red Giant's Line (part of Universe) does this too (even though you're a bit restricted on the shape of the path).