I've been tapping my head to this issue for a little while now, and I would like to reach out for some help.
I am trying to create an animated line that flies around and moves around objects on the screen. While the line slithers around, it will change in "thickness." Ideally, the effect I wanted to achieve is similar to a snake moving around the screen that can increase or decrease in width (have the snake grow fatter or skinnier while it moves). So far I've been able to have it move around on a path, but I can't seem to find the ability to make it fatter/skinnier while moving on the path without it being displaced from the motion path itself. Here are a few ways I tried but ran into problems with each of them:
1) I've tried creating a CV curve as a path for a line (or tube, since it can change thickness?) to move in, and created a cylinder to "attach to motion path." Then, I created a "Flow Path Object" on the cylinder for it to move more smoothly. The issue I've encountered though was that I couldn't change the diameter of the cylinder without it distorting or going off pivot (even if I manipulated the scale option of the cylinder, lattice shape, and baseShape combined.)
2) I kept the same CV curve, but instead of creating a cylinder I created a NURBS circle and extruded it along the curve to create a tube. I could key the subCurb values to "animate" the movement of the tube, but I am left without the ability to manipulate the "radius" of the tube without it distorting/moving away from the pivot.
3) Same as #2 but instead of extruding with a NURBS circle, I extruded using the polygon faces of a cylinder. I lose the ability to key subCurb, and from there on I was unable to figure out a way to continue with this method.
I feel more inclined to continue with the second method because it was much simpler to just manipulate the subCurb value. However, adjusting the scale attributes of the extruded mesh did not simply increase its diameter, but expanded the entire mesh (not sure if I was able to word that correctly without confusion). I wonder if there are any solutions to this issue. I feel that I am missing something trivial that would solve this immediately.
I appreciate any input.