Do I remember there was a Constraint that slides an object on surface of another?


I am sure a fair while ago I saw a kind of rigid-body way to slide one object over the contours of another object… a bit like Shrinkwrap constraint in that it does not deform the mesh, except it would also tilt the object’s extremities so no intersection with other object occurred.

You’re probably thinking of the floor constraint. However if you’re using it on objects, it only cares about the location of the object, not the surface of the mesh, i.e. its origin point. With a plane mesh the origin is generally in the middle of the plane, so a constrained object won’t pass through the plane, but with something like a cube, an object can pass halfway through before it hits the stopping point. Also of course the constrained object behaves similarly; its origin won’t pass beyond the target object’s origin. So place those origin points strategically.

Alternatively, you can use the constraint on bones. In the case of bones, the constrained bone’s root will not pass the root of the target bone.

You can achieve this by using a plane with a shrink-wrap modifier on it. target it to the mesh you are tying to slide along. Then you can subdivide it and create vertex groups as needed. Then on the object you want to slide along the surface add either a child of constraint pointing at the plane with the shrinkwrap on it, or, use a copy location modifier. There are other potions as well.

If you search for the car rigging tutorial that uses a cloth simulator for the suspension it has several concepts that will help you with your goal.

I’m still new to Blender myself and I am not at my Blender computer to give exact details on the process but this should get you started.