Putting an arrowhead at the tip of a written-on line.

[Kevin Camp]

you can use a simple expression and the auto-oreint feature to place an arrow at the end of the line…

first, create an arrow head, due to how auto orient works, it will be slightly easier if the arrow is pointing to the right.

once you have you’re arrow, you can attach it write-on brush position with an expression. select the write-on layer and twirl down the properties until you get to the ‘brush center’ property. select you arrow layer in the timeline and hit ‘p’ to reveal the position property for that layer. select the position property and choose animation>add expression, then use the expression pickwhip for the property and drag it to the ‘brush center’ property of the write-on layer. the expression should look something like this:

thisComp.layer(“White Solid 1”).effect(“Write-on”)(“Brush Position”)

now the arrow should be at the end of the line as it writes on. to get it to rotate as it moves along with the line, you’ll need to enable auto-orient. select the arrow layer and choose layer>transform>auto-orient. select the ‘along path’ option.

now the arrow should move along and rotate with the line as it draws on.

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW

[Andy George]

Hi Mark,

You could link the arrow head to your write-on brush position using an expression.
option click on the “arrow” layers position property to reveal the expression controls.

Grab the quickwhip (curly looking thing) and drag it to “brush position” under the write-on tab
of your write-on layer.

The resulting expression should look something like this
thisComp.layer(“Write on layer”).effect(“Write-on”)(“Brush Position”)
(layer names on your comp will be different so it wont match up exactly)

This will take the position of your brush and feed the numbers to the
position of your arrowhead.

If it does not line up correctly you can adjust your arrow layer anchor point (see pan-behind tool)
to move into alignment-

Andy

[Mark Von wahlde]

When I use a shape layer, the expressions do an excellent job of making the position numbers match exactly.

Unfortunately, the correct numbers appear to relate to the comp, rather than to the (really big) layer that has the map and the write-on effect on it. The result is that my shape layer’s motion path is WAY off the composition’s display area.

Any ideas?

BTW, this stupid problem has really helped me learn a lot so far!
Thanks

[Mark Von wahlde]

Your tip works perfectly if I apply the expression to a paint object that I applied to the same map layer. Thanks very much!

But I want to figure out how to get a shape layer to track the write-on motion path applied to my map layer!

[Mark Von wahlde]

I figured it out, with your help! Expressions makes the position numbers equivalent and making the arrowhead the child of the parent takes care of the rest.

Thanks again!

[Jon Larson]

Would anyone know how to do all this but with out using write-on. I want to achieve the same result ie. a traveling arrowhead but as a line graph with sharp corners as the line goes up and down. It seems the write-on creates soft corners.

Is there a way to do the same thing using a keyframed path on a shape layer or something?

hope that made sense.

Jon