Pre-comp uses parents time line?

[Dan Ebberts]

You have to know the name of the parent comp, and then an expression can look for its own comp as a layer in the parent comp and compensate for the offset timelines with something like this:

C = comp(“parent comp”);
ctrl = C.layer(“controls”).effect(“Point Control”)(“Point”);
L = C.layer(thisComp.name);
ctrl.valueAtTime(time+L.startTime)

Dan

[Paul Stevenson]

Dan thanks for the response and sorry for the delay in getting back to you, I have been busy on other projects and just got back to this today.

I am not quite sure what your code is doing and I definitely couldn’t get it working, but I am a bit of an expressions noob.

However I did manage to find a solution.

As I said, I am passing values from the parent to the child, so I merely adjusted those values. Instead of using a straight…

timeToFrames(thisLayer.inPoint)

…on a slider that is then read by the child, I adjusted it a little:

TimePoint=timeToFrames(thisLayer.inPoint);
TimeOffset=timeToFrames(thisLayer.startTime);

TimePoint-TimeOffset;

For the benefit of anyone reading this that doesn’t understand the above:

This now takes the in point and the point in time on the layer that it starts (subtly two different things – one being a shifted time and one being a cropped to time – It’s quite probable that both can exist at the same time) and takes one from the other. This calculates the time adjusting for offset. The child can then read this.

For anyone looking for code on how a child can read something from the parent, this will get you started:

comp("Parent").layer(thisComp.name).effect("Slide START")("Slider");

Just in case anyone is searching for the same things I was a few days ago.

[Josh Acason]

Man. Thank you so much Dan! 6 years on, I really appreciate your contribution, made an account just to say thanks haha.

 

I used your expression to send trapcode soundkeys values back to a child comp – it’s so obvious when you know, but thank you man.