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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.
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
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Copy and paste the Paint Brush Path to the Motion Path.
You can adjust the timing by clicking and dragging either the first or last Position keyframe.
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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?
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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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Since this is the result of a path being pasted to a Motion Path, there's no need to hold the alt/option key when dragging the first or last keyframe. This changed back in CS6 or CS5.5 or... I forget when.
If the Position keyframes were created from scratch (rather than pasted from a path), then yes, you'd have to hold alt/option as usual.
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Thanks guys, I'll give that a go.
I was really hoping there would be a way to link via an expression to the end point of the brush stroke. There's a terribly simple way in Apple Motion to do this, but a lot of the artwork given to me uses Darken transfer mode, which Motion doesn't offer. grrrr.
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Maybe you can split the difference.
Motion used to allow you to change the project file extension from .motn to .mov and then import that into After Effects directly; however, that was all via QuickTime. This required that Motion and AE be on the same machine.
If if this still works, maybe you can do the paint and position in Motion and move to AE for the Blending Mode (if the layering can be worked to allow for that in the first place).
It it might not work any more anyway. Apple's switch to AV Foundation Frameworks eliminated almost everything that QuickTime did.
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Using the mov idea to go from Motion to AE... for those that might read this thread... nope, this no longer works... tested, failed.
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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
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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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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.
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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.
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BTW I used an expression here but you could just as easily copy and paste the KFs
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Thanks Angie, but the problem is I need to do this the opposite way - freehand brush to reveal the artwork, and then link the "pen" to the brush path. I've got too many bits of artwork to reveal to KF the reveal, and I prefer the natural motion of drawing freehand vs setting KFs.
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You can move the brush freehand by using Motion Sketch? then apply it to the Write on effect? that way you still get the natural motion?
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hmmmm........ I'll give that a go.
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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.
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But when you preview this, don't they run differently? Also, in your screenshot, the Stroke End KF is at :03 (about) and the pen final KF is at :02
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Nope, they run exactly the same. I'll render a movie to show you. When you use the Write On mode it records the stroke in real time, then when you copy and paste it, it will work out the timing correctly.
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It's not easy, I think that using Motion Sketch to record the motion and then applying this to your pen is the easiest way.
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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.
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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.
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Yeah, the trouble is that the End Position is animating Linearly from 0 to 100% but the Position value is not linear in it's interpolation. Thats Why the Write On effect is a better bet as it has a Position value as opposed to an End value. So it's absolutely the same.
As a workaround, draw the paint with the Paintbrush, copy it, paste it to your pencil position. Then also paste it into Write On effect > Brush Position value. Now you'll have it working, use that as a template to line up the brush stroke correctly.
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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