Path shape to null

[openskies2009]

I have a shape that is 3d which I have a path which I am extruding with a stoke. I am aniumated this stroke to draw in from Ney York to all parts of the country which lands on a center of two layers which animates a radar effect. Problem is I need both the path and these layers to align perfectly. which is hard to do by hand. I have found this script whcih is exactly what I am looking for https://nomagnolia.tv/ae-link-path-points-tangents-nulls/ but it does not work on shape layers. Any suggestions?

[Mylenium]

The simple answer would be that you should have done it with the Beam effect and some tracking in 2D or created some expressions to target the 3D layers in the first place. To be honest, you likely should probably simply scratch the whole project and start over. Using the Beam effect would be almost ridiculously simple (even if you were to move the end points manually) and if you really need 3D, there is any number of targeting expressions like lookAt() that could orient a thin solid towards a Null parented to your map and moved in place over the radar points. You can find enough examples for that in a simple web search.

Mylenium

[Rick Gerard]

The biggest problem you are facing is that all vector paths, whether on a shape layer or as a mask path, are drawn on the layer's X Y-axis. There is no 3D information. 

The only easy solution that I can find is to keep all of the layers on the same Z plane and treat them as 2D layers. You can then copy then the path in the shape layer, paste the path to the position property of the radar effect layer. It is then easy to time the Range Selector that sets the end of the line to the by simply dragging the start and end keyframes into alignment. When you have a radar effect layer matched to the endpoint of a stroke animated using the range selector you can then parent the layers together, lock one of them, make the layers 3D and then rotate them into position or add a camera. 

The only real thing wrong with your workflow is trying to tie the position and animation to the stroke using expressions after turning the layers 3D and not matching up anchor points and angles. 

The script that attaches nulls to vertices is now outdated by the Nulls to Paths script that comes with After Effects but it would be pretty useless in this design unless you added a bunch of other expressions that calculate tangents, angles, and use layer space methods to figure out how to point one 3D at the end of a path animated by a range selector and Trim Paths.

Here's the workflow once again:

1. Draw your path on a new shape layer with the pen tool
2. Press UU to reveal all of the modified properties of the path
3. Select the Path stopwatch and click to set a path keyframe (makes sure that you actually selected the path) then cut the keyframe (Ctrl/Cmnd + x)
4. Select your radar layer with the center of the radar effect on the anchor point of the layer, press Alt/Option + p to set a position keyframe then Ctrl/Cmnd + v to paste the shape layer path to the position property
5. Back in the shape layer ADD a Trim Paths animator
6. Animate the range selector to draw on the line
7. Select both layers and press the U key to reveal the keyframes
8. Drag the end of the position keyframes for the Radar Layer to match the timing of trim paths
9. Parent the radar layer to the path layer, make them 3D and adjust the final look using the camera or by manipulating the parent