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# Re: Parenting the Separate Ends of a 3D Object to Two Different Nulls?

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 Re: Parenting the Separate Ends of a 3D Object to Two Different Nulls?on Mar 2, 2019 at 12:29:25 am

Hey Rikk,
You have to think about it the other way round.
Element lives inside of AE is just a flat layer. So its best to send the values of the 3D AE null layers into the values of the objects (or "particle replicator positions" as Element calls them - under each "Group"). The position and rotation of those particles shows up in the effect dialogue for element. This wont be a simple pick whip thing for a number of reasons:

1) the position of objects in Element don't always relate as one might think to the outside world of your AE comp. So there's usually an offset that's required where you will add a constant value to the expression math you get from the null's position (which you could pick whip, but only to get the initial raw value of where the null is) to feed into the object's position in the Element effect dialogue.
2) for this kind of animation you can either use the cloning tool inside Element or as Michael pointed out (all refreshed with his new avatar - so that's why he's thinking so far ahead of the rest of us aging fx artists: he's soo young!), you can make what amounts to an IK chain with a set number of objects in Element - each would be in its own group. (the key to Ik chains is what the objects "look at" as they move around.) Again these are calculations you have to add into the expression that drives where the "particles" are positioned.

So while this is doable in AE, I think its' going to be easier in C4D for a bunch of reasons.
1) You can have C4D set up the IK for you and it just kinda works.
2) you can impart dynamics and self collision math with just a few buttons pushes - this is perfect for chains.
3) the data from the nulls and the camera and the lights in AE can be sent into C4D (and visa versa) so that everything lines up and you have targets to play with in your IK chain.
4) you'll probably have better luck with any depth effects (including penetration) like haze or blur.
5) you might also have better luck with the motion blur in C4d. When you get into expressions often the thing you want to blur isn't moving as far as ti appears to be so AE blurs it minimally.

Then the only decision is whether to have C4D render the chain and you comp the resultant frames in AE or you have AE do the C4D render for you and bring in the C4D project in as a layer in AE. Keep in mind that while you are getting the image of true 3D geometry in the C4D layer inside of AE, it's only a layer at that point and as such is flat. So if the chain goes into the distance, and there are other objects near the chain, the c4d layer will only overlap those AE objects that: are below it in the layer stack, or if the chain's layer (assuming a 3D layer) is above the zdepth assigned to the 2d "cards" of all the other 3d AE layers

I'm not sure if packages like DUIK (free by the way, but there are others) can do IK chains in depth or not but you could use them to animate dummies or nulls in AE and then get the data from those and pass the position and rotation data of each to element3D objects.