Hi!
I'm working on tutorials about these kind of stuff, I'm trying make this available quickly but it's a lot of work
When you connect your slider to properties, if you have only one connection to make, it's pretty easy: just do your animation and connect the slider.
Your problem is that you want to make several connections to the same property, which is not (yet) possible (I'm thinking about how to make this possible, maybe one day I'll find out...).
The solution depends on the type of property:
• If you're trying to connect
transformation properties (i.e. position, rotation and scale), the quickiest and easiest way is to
use parents: for each new connection, add a null layer, and parent the already connected layer to this null. You can then connect the transformation of the null object, and you can repeat this process for each new connection you want to make.
• For other
numerical properties (including transformations actually) you can
use the "list" tool of Duik, which is available in the link & constraints panel (in standard and expert mode only, it is hidden in rookie mode).
Just select the property, and click the "list" button. Duik will add an effect with 5 new properties to control the original property, allowing up to five connections (or even more if you add a list to the list....). With the list, you won't connect the original property, but one of the new properties in the list effect.
• And there are
non-numerical properties, like Bezier paths....
Here it's tricky if you're using an version of Ae
older than CC2018: with older versions, there is no way to efficiently work with shapes in expressions, so
you can not do more than one single connection to the shapes (to your X OR Y slider, but not both). The only way to achieve something is by duplicating the bezier path and try to make it work, but it can be very difficult.
Using masks can help: instead of connecting the original shape itself, connect masks which "cut" it, or in shape layers
try using multiple shapes and the "merge path" option (which works like the pathfinder of Adobe Illustrator).
If your
using CC2018 or any more recent version, you can
add bones to the bezier path (select the path property, or any vertex of the path, and click on the "add bones" button in the links & constraints panel of Duik). This way you'll have one layer for each vertex (and tangent) of the path, and you can then connect the position properties of these bones, and get back to the first and second method (connecting transformations or numerical properties).