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spillt

custom parent expression in AE

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Does anyone know of a way to animate the influence of a parent on a layer? For instance: I have a footage layer and a copy of it that is motion tracked and stabilized. I want to slowly animate in the stabilized keyframes so the layer will become stabilized over a 5 second interval. I've tried to use the "ease" exp​ression on the non-stabilized layer's position property without success; most likely because I don't know if its the one I should be using...

 

t=15,

x=160,

y=570,

[ease(t, x, thisComp.layer("FootageStabilized").transform.position[0]), ease(t, y, thisComp.layer("FootageStabilized").transform.position[1])]

 

Any thoughts/suggestions would be much appreciated,

Thanks!

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I would make an expression slider control and use that as a 0-100 value for the influence percentage. You could use some very simple math to get a weighted average between the layer's current position and the tracker's position. You could then animate the slider to control the level of influence. I can make an example file later today if that would be helpful.

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You can use the ease if you want, but your current setup is using it incorrectly.

 

Try this:

target_layer = "foo";
start_value = position;
target_value = thisComp.layer(target_layer).transform.position;
start_frame = 0;
length_of_blend = 60; //in frames
progress = (start_frame + timeToFrames(t = time + thisComp.displayStartTime, fps = 1.0 / thisComp.frameDuration, isDuration = false))/ (start_frame + length_of_blend);
ease(progress, start_value, target_value);

 

Documentation on expression interpolation methods can be found here:

http://help.adobe.com/en_US/AfterEffects/9.0/WS3878526689cb91655866c1103906c6dea-7a06a.html

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