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Animation: Bending, growing arrow - how to? (video added)

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Roger Maus
Animation: Bending, growing arrow - how to? (video added)
on May 13, 2013 at 4:54:55 pm

I am trying to animate an arrow that changes its shape. (A plus would be to let it grow, but this is a minor problem I think. e.g. "Stroke")
The main problem is the auto-orientation of the arrowhead if its line (i.e. its main body) is a path/mask.
Since I will need a lot of these arrows (in different lengths) I need a solution which is easy to handle and modify, once its setup is built.
Distorting or deforming it isn't exact enough, doesn't give me smooth curves and tends to shift the proportions of the arrow(head).

Arrowhead gone mad

animated line

I think this problem is very closely connected to the impossibility of linking a null to a vector. And the impossibility of establishing a path animation along an animated path (as shown in the videoclip).

Any hints or workarounds?

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Dave LaRonde
Re: Animation: Bending, growing arrow - how to? (video added)
on May 13, 2013 at 5:08:04 pm

The Write On Effect will do what you seek: you copy the motion path into the Brush Position Property.

You can also use the same motion path to animate the arrowhead's position property, and tweak its anchor point to taste.

Dave LaRonde
Former Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA

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Roger Maus
Re: Animation: Bending, growing arrow - how to? (video added)
on May 13, 2013 at 5:58:03 pm

The effects puts out a line that follows the mad orange arrowhead. It doesn't seem to work with an animated path? But this is what it's all about. Am I doing it wrong?

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Kevin Camp
Re: Animation: Bending, growing arrow - how to? (video added)
on May 13, 2013 at 7:05:02 pm

you won't be able to copy/paste an animated mask path as a motion path... ae will see the animated mask path keyframes as separate motion paths and give you the wonky behavior in your first example.

write-on won't allow the brush path to be animated once it's been drawn, so that won't work...

expression can't access mask data either...

if your curve is simple (like in the first example), you can use cc bend it to distort both a straight line animating on, and an arrow head moving across (like it's wiping the line on), in a way that looks like the path starts curved, then goes straight as it draws on...

try this:
  • create a horizontal line that wipes on (left-to-right).
  • create an arrow layer, and animate it moving left-to-right, timed with the wipe of the line.
  • create a new adjustment layer, add cc bend it, set the 'start' to the right-most point of the line (the 'start' is the static point) and the 'end' to the left-most point of the line. then animate the 'bend'.

Kevin Camp
Senior Designer

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Roger Maus
more information
on May 13, 2013 at 10:34:17 pm

Thank you for your reply, Kevin.

Using your instructions, this is what I got:

hail of arrows

This is not at all what I wanted to get, but I had fun with it.
"CC Bend It" does not give me enough control over the start and the end of the arrow. Furthermore, I could only use it for some very basic bending.

You know, I'd like to make an animated infographic, where both the object and the explanation is moving - and so is the connecting arrow:

...and it's not only three objects!

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Roger Maus
*seemed* so simple!
on May 14, 2013 at 9:43:09 pm

I think the crucial thing is to get an auto-oriented object to a moving, changing shape/mask/path.

Any more hints?

With all the hilariously moving shapes, all the motion graphics flooding the internet, I still refuse to believe that it is impossible to built a quirkily bending arrow!
A moving snake, reptiles in general!
A rising balloon!
A sperm!
A garden hose!
Anything with a head and a tail to follow!

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Michael Garske
Re: *seemed* so simple!
on Mar 16, 2014 at 5:52:21 pm

I'm trying to loop arrows along a motion path as well. I'm some what new to After Effects though so here is as far as I've gotten :

- shape layer with dashes that have animated offset to get the tail of the arrow to conform to the bends of the path.

- shape layer for the head of the arrow that is keyframed to follow the motion path with a looping expression.

- duplicated the arrow head multiple times and offset those layers in time to get multiple arrow heads to loop


The issue I have is that the arrow heads won't exactly time with the beginning of the dashes. Anyone have any suggestions?

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Adrian Thompson
Re: *seemed* so simple!
on Feb 10, 2015 at 10:35:14 pm

We just created a script that automates this entire process. You can attach an arrow (or any shape / custom layer) to the front and end of a stroke with the click of a button. It also allows for easy updating of the mask path after creation.

See it in action here:

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