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Dashed stroke following a motion path of another layer?

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Julie MullinsDashed stroke following a motion path of another layer?
by on Jan 20, 2015 at 3:59:52 pm
Last Edited By Julie Mullins on Jan 20, 2015 at 5:25:02 pm

Hi guys,

I have a fly that needs to move up and down the screen (see image below- the amount of up-and-down points will be even greater than these), leaving behind a dotted line trail that stays on the screen. Is there any way to make an expression to have it do this so I don't have to make a separate stroke path layer? I feel like there's gotta be an easy way to do this and I haven't been able to figure out a way yet (I posted this in the Expressions forum as well). If not an expression, is there another easy way to do this? Bottom line is if the client comes back with changes I don't want to have to edit both paths. I feel like I'm overlooking some really easy solution here.

I should note that how I'm doing it right now is having a stroke adjustment layer parented to a null with the copy/pasted position motion path on it. Then I am keyframing the end position to follow the fly. But what I'd like to do, ideally, is some how parent the start/end time of the stroke to follow the fly without me having to keyframe it... if that's possible....



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Derek BoettcherRe: Dashed stroke following a motion path of another layer?
by on Jan 21, 2015 at 3:35:54 pm

Here's what you do:

Copy the position data that you have by clicking on the Position propert, and hitting cntrl (or cmd) + c. Then right click, add shape layer. Under contents, add a path, stroke and trim paths. Paste the position data on to the path by selecting the path property, and pressing cntrl (cmd) + v. ON your stroke, change the color to black (or whatever you want) then under dashes press the + button. Change the width of the dashes and gaps settings to get what you want. Under the trim paths, key frame the end from 0 to 100% following the path of your bee.

There ya go. Lastly, play with the settings to get the timing and look the way you want it.

Hope that helps

Best,
Derek Boettcher
Creative Management
BTH Media Group
http://bthmedia.com


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Julie MullinsRe: Dashed stroke following a motion path of another layer?
by on Jan 21, 2015 at 4:46:41 pm

Thanks for responding, Derek! This is similar to what I am doing now. I'd really like a way to somehow parent the line (and start/end stroke) to the fly's position so I don't have to edit both paths separately and the re-keyframe the start/end stroke and re copy/paste the paths if a change needs to be made later. Is that possible?


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Derek BoettcherRe: Dashed stroke following a motion path of another layer?
by on Jan 21, 2015 at 4:52:13 pm

I don't think so, at least not without a 3rd party plugin. Personally, what I would do would be to keyframe your bee from start to finish, exactly like you want it, and then do the stroke last instead of trying to do it all at once. It will just save you time and frustration, and will help keep the comp cleaner.

Another way to have this effect, but without the line moving, is to precompose the stroke's shape layer and then reveal it with a mask or track matte (instead of using the trim paths property).

Hope that helps. If any of the other folks here can think of a way to do that automatically then I'd also like to know! (You may want to try the guys on AE expressions forum, they may be able to help with an expression to do just this)

Best,
Derek Boettcher
Creative Management
BTH Media Group
http://bthmedia.com


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Julie MullinsRe: Dashed stroke following a motion path of another layer?
by on Jan 22, 2015 at 8:54:13 pm

I got an answer in the expressions forums, and it works exactly how I need it to:

https://forums.creativecow.net/readpost/227/28884


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