2 questions about modifying spline points over time

  1. Can a spline point be added or removed from a shape after a certain frame without deleting it across all frames for that layer?

  2. On that note, is it possible to create a layer, remove the entire shape in the next frame and add a new one without deleting the layer itself? For example, if there is a very complex object that would continually require the addition/removal of many spline points, to the point where it would be easier to redraw the shape with each frame.

For #2, the only solution that comes to mind is creating a new layer for each frame and setting the in/out regions for each layer to the frame that the shape is drawn, but I’d like to think there’s a better way.

No. The usual technique is to create your first keyframe on the frame where the most points are needed. @maryp might come along later with some tips on this.

The nearest thing is you can enable and disable individual points. Right-click on the point and choose Point | Deactivate. This sets a keyframe if you have autokey on, using this you can set active time ranges per point.

The down-side to this is that other applications don’t support this concept, so you’ll have to render the mattes using Mocha itself rather than exporting them to another application.

You can use the point deactivation approach but it’s not ideal. A better way would be to have an underlying layer that you use for tracking, which exists through the whole time range, then make other layers for your roto that you connect to it using “Link to track” in the layer properties. Each of those other layers can have whatever duration it needs and a completely independent set of points.

Hope this helps,


On point 2. Simply use the Layer In/Out points to have one layer stop and the other layer pick up without deleting the layer OR animating it off screen.

As JP, mentions both layers could be linked to the same track layer, so the general motion will feel smooth.

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I came to chime in here that I really do not recommend using deactivation on points, simply use the points you need and switch shapes to overlap if you start to need less. You can link all shapes to the same track so you don’t get any jitter and just adjust the in and out points for those layers, though instead of in and out points I actually recommend animating them offscreen because not every program you export shapes to recognizes in and out layer points either, like After Effects.

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@maryp @rosss
Thank you all for the responses, I’ll try the methods suggested, you’re always very helpful.

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