Linking to a spline linked to a spline

I’m trying to get a region vertex to follow a path near a spline, not the spline itself. My strategy (which doesn’t work) is to link to a spline that’s already linked to the spline. That’s a little hard to describe, so I’ve included some images below.

Step 1: Create the first spline. This is the spline to be followed.

Step 2: Create a second spline, just a straight line. This is the spline I’d eventually like the vertices to follow.

Step 3: Place the second spline in a group layer and link its transformation handle to the first spline. Now it nicely follows the first spline while conveniently putting its two vertices perpendicular to the spline I’m following. If I could follow those two vertices, I’d be set.

Step 4: Create a region.

Step 5 (doesn’t work properly): Select both the region layer and the second spline layer. Link a vertex of the region to the second spline. What happens is that it links to the place where the spline was before it was transformed. I even understand why: the region vertex is “blind” to the group transformation that is responsible for the second spline’s attachment to the first spline. Of course, when I place the entire region within the group layer, all of its vertices transform as the group is transformed, which is unacceptable.

What is by far most important to me is that I am able to link a region vertex to a spot perpendicular to a spline via a single “Amount” parameter. I don’t really care how. Is there an obvious way to do this that I’m overlooking?

I followed your initial example, but I put the white region in its own group and placed that in the group of the second spline under the actual spline. When you then change the position of the second spline along the path, the white region follows.

edit: Oeps, my bad. You already tried that… :blush:

But I don’t want the whole region to move with the spline, just some of its vertices. I’d (eventually) like the region to “grow” around the first spline.

The closest thing you can do is to create a ghost spline parallel to the one you want to follow and use it as guide for the vertex of the region:

Yeah, that’s what I’m coming up with. I may just do that. I’ll see if it gives me the results I’m looking for.


Edit: Nope, didn’t work. I was hoping to also link the tangent handles to the splines (or to other splines) so that it would create a rounded front to the curve. Instead, I’ll be animating things manually through waypoints, as I’ve been doing.