Hi!
Is there any way to connect the path vertex to null objects, or point control, or anything?
The beam is not good for me, because it is a straight line, and i would like a beizer. The puppet tool also does not good, because it distort my thin line. I don’t find the soultion yet…
Ha! You will resolve it if every buyer has this script too. 
You have only one way to solve it. Create a really smart expression. You need a circle and a mask on it. Expression gets position from nulls and find the right position for the circle. Some piece of it will be under the mask. Another piece will be an arc line that connects two nulls.
It’s not perfect. And really hard to do. So good luck! 
The circle is an animation, it does not matter from this point of view, i can easily connect it to tracked nulls. The problems are with the simple shape line. The line shape has one start (A) and one end (B) point vertex. I would like parenting this A and B vertex points to the two separate tracked null objects.
If i buy this script, and create from this 2 vertex one line-shape with “trackable” A and B points, buyers can’t edit it without script?
Maybe this, but i would like work as professional…
Effects > Obsolate > Path Text and using many “-------------------” character to visualize something like this
Circle is an ellipse. I mean something like this:
https://drive.google.com/file/d/0B1kJRjBcSdPKcmZOM3d0ME84TWs/view?usp=drivesdk
Red dots are your nulls. Black part of the circle is visible line. Blue part will be hiden under a mask.
Expression can’t control vertex, only a script and plugin can bo it. But you need the script or plugin in every machine to make it work. End of story.
Oh, i would like tracking the line A/B vertex, what is between the human and the circle target. I speak about this big dashed line, not about the ellipse animation.
Sorry.
Oh. 
Is it so hard to understand what I’m talking about?
ok i understand now, i tought you mean the 3d perspective animation circle, at right side.
but i don’t understand, what makes are nulls with mask? the people is moving (A point), and the perspective animated circle target is also moving, (B point). What can i attaching to your two null objects?
So circle anchor point would be at null A (the man on picture). Also circle would be parented to that null. So it would move with it.
Now we need lookAt() function. It helps to rotate circle and “look at” null B. (You also need some rotation correction, depending how much bend would be the line.)
Then you need length() function. It would calculates the distance between two nulls. That way you can control the size of the circle.
It’s basic plan.
Uh, im afraid, buyers can’t remake this method easily with their own projects : S
It will work automatically.
UPD: https://youtu.be/_JR-pFXK6sY 10 min of work. Of course, it’s rough variant.
Im not so good in expressions, i never heard about lookAt() function, can you provide me for the Ae file? I can buy one of your items! Im not lazy, but now I working on the widgets, and finally, that was your creative solution…
No need to buy anything. I made it just for fun!
Go and get it here.
There is one disadvantage. You need manually control bend of the line. I’m too lazy to make it automatic. Sorry. 
So to do it, you need to change X Rotation, and “1.41” number. (Turn “arcLine” mask off).
The circle line must go through null B. Then turn mask on, and also manually change its shape to hide the part of the line you don’t need.
For example, X Rotation = 0, and “1.41” number = 1, make the line to be as half of a circle.
Thank you so much Dogmotion! Check your reviews ; )
Thanks! 
But that was really no need to do it.
Feel free to contact me if you will have other questions about expressions in future. 
