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EditingBob
Inspiring
September 20, 2017
Answered

Paint brush path - use for linking object motion?

  • September 20, 2017
  • 5 replies
  • 6777 views

Searching everywhere and can't find if it's possible to link a paint brush path to another object's motion parameters.  I'm drawing with the brush tool to create a reveal effect, and would like to use the brush path to drive an animated pen. 

    This topic has been closed for replies.
    Correct answer EditingBob

    Hi EditingBob,

    Sorry for this issue. Did you ever find a solution? Please let us know if you have or if you still need help.

    Thanks,

    Kevin


    I need to fix my name!  It's Bob Woodhead... appreciate all the answers you've given folks over the years, Kevin.   Anyway, yup, solution was to just go back to Motion.  The process is super easy and close to perfect alignment.   Sometimes some segments of the motion path don't link perfectly temporally, but not enough to be a problem.  But the good thing is there's zero mucking about, just apply brush path as a motion path for the hand, and done.   I admit to often using the approach that works quickly instead of elegantly. 

    5 replies

    angie_taylor
    angie_taylor
    Legend
    September 22, 2017

    BTW, I'm not sure if Paint and Stick would help you out at all. Worth checking out

    Paint & Stick 2 - aescripts + aeplugins - aescripts.com

    angie_taylor
    angie_taylor
    Legend
    September 22, 2017

    OK, I have managed to get it working for you! :-)

    When you paint, use the Write On Duration method. Then select the Brush Path property, copy it.

    Now when you paste it in (without changing anything) the End of the line matches with the Brush tip.

    angie_taylor
    angie_taylor
    Legend
    September 22, 2017

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    EditingBobAuthor
    Inspiring
    September 22, 2017

    Actually, the timing does not match perfectly. I think the only way is to keyframe it. There may be a script or expression that can help. I'll see what I can dig out.


    Yeah, I was really hoping there'd be a way to link to the Brush path end position via expression, but I couldn't find anything.  Lots of info on linking to stroke paths, but not a brush path.

    angie_taylor
    angie_taylor
    Legend
    September 22, 2017

    You can just copy the path from the Brush Position property to the Position property of your pen. Click on the Path property to select it. Hit Copy. Select the Position property of the pen or pencil Position property and hit Paste. You may need to adjust the Anchor Point value so that it's on the tip of the pen or pencil.

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    EditingBobAuthor
    Inspiring
    September 22, 2017

    No matter what Duration property I use for the original brush stroke, after using the time stretch keyframe option above, the positions of the pasted keyframes don't match in time the brush animation.  Changing Rove across Time or interpolation doesn't help.

    The start & end KFs match, but nothing in the middle.

    angie_taylor
    angie_taylor
    Legend
    September 22, 2017

    Yes, it can be tricky to get timing to work without adding way too many KFs. I prefer to use either the Write On effect or Stroke for this kind of work. Write on is great as it has a Brush Position value. In this example I have linked the Brush Position of Write On to the Position of the pen point, it works like a treat.

    angie_taylor
    angie_taylor
    Legend
    September 21, 2017

    There's an easier way to create a reveal using paint. Paint on the layer you want with at the brush set to Alpha and Write On, then you can literally paint the video on over time. Here's a tutorial that will help you set this up;

    Basic Drawing and Painting in After Effects from: Wacom MasterClass Complete Collection - YouTube

    Warren Heaton
    Community Expert
    Warren HeatonCommunity Expert
    Community Expert
    September 20, 2017

    Copy and paste the Paint Brush Path to the Motion Path.

    1. In the Timeline panel, expand the Paint effect until you see the Path parameter of the Brush that you want to use as a Motion Path.
    2. Click on the Path parameter to select the path and then choose Edit > Copy.
    3. Expand the Layer that you want to have the Paint Path as a Motion Path so that you can see its Position property.
    4. Click once on the word Position to target it and then choose Edit > Paste.

    You can adjust the timing by clicking and dragging either the first or last Position keyframe.

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    EditingBobAuthor
    Inspiring
    September 20, 2017

    Thanks Warren, I'd tried that, but the resultant keyframes don't line up in time very well.   I could try to go in and time adjust the pasted keyframes, but I've got a LOT of this work to do, and I know what a PIA doing these kinds of adjustments can be. 

    Or maybe I'm missing a good fast way to make the keyframes match the original Paint path?

    Mike_Abbott
    Mike_Abbott
    Legend
    September 20, 2017

    EditingBob,

    Select all the keyframes you've pasted. drag them in time so the first one lines up in time with the first keyframe in your paint stroke - ie, the first keyframe you copied. Now, with them all still selected, hold down the Alt key and drag the last - in time, keyframe. The selected keyframes will stretch or shrink in time while retaining their relative positions. You can therefore stretch them in time to match the paint stroke from which they were copied.

    Keyframes pasted in this manner have a default 2 second duration - hence the mistiming.

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