null slide on curve

[McNistor]

Is it possible to have an effector constrained to a curve so that when you move the root around it slides on the curve? Path constrain is obviously not the solution since it's not interactive.
Possible with "normal" rigging tools or should I investigate an ICE approach?

[EricTRocks]

Definitely need ICE for this. Need to get closest location on the curve. A tip, you'll have to put your ICE Tree on a static null at world zero, get the position you want to use to get the closest location (maybe the root's kine.global.pos?) and set the location as an attribute. On the ICE Tree for the effector, look that attribute up from the static null objects and set position from there.

[McNistor]

Thanks for the tips.
It turns out I don't need this anymore, but if I have the time I think I will try to do it anyway since it may be useful in the future. I will surely post it here if I manage to pull it off. Not an ICE guru here and in fact, very far from it.

[SpookyMunky]

I dunno if its a "Definately use ice" kinda thing ?, jsut to be annoying, could setup a quick link with on the path age.. depending on the situation might work just as nicely as ice / better since you can adjust the link with curves to your taste... just being devils advocate

[EricTRocks]

Well since the OP said that the path constraint wasn't an option as it wasn't interactive it led me to believe they wanted it to be automatically calculated with little to no manual work. I said you'd get better results with an ICE based driven one any way.

[McNistor]

I dunno if its a "Definately use ice" kinda thing ?, jsut to be annoying, could setup a quick link with on the path age.. depending on the situation might work just as nicely as ice / better since you can adjust the link with curves to your taste... just being devils advocate

When I drag the selected root null (like in the pic) I want the effector to follow and obviously stick on the curve. How do you propose to achieve this with path constrain? Or did I misunderstand you?

[Mathaeus]

When I drag the selected root null (like in the pic) I want the effector to follow and obviously stick on the curve. How do you propose to achieve this with path constrain? Or did I misunderstand you?

Obviously I'm not SpookyMunky, but anyway
If animating two objects is an option, then yes, could be one null constrained to path, effector will be constrained to this null, using pose or position constrain. Finally, root can be constrained to this null, using distance constrain, where distance is equal to bone length.
Or something else along this line.
By the way, by using only one animated object, won't be easy with ICE too. It's not only closest location, there's actually offset to calculate. Finally, direction - on which side of root, null will stick.
Do you know for working solution in another 3d app ?

[pezetko]

There is my solution, no obvious cycle dependency.
It's just quick test, not ideal solution. I just like solving problems. Maybe there is much simplier way how to rig this. I don't do heavy rigging in softimage, so I would like to see other solutions too.

*.gif demonstration here:

http://postimg.org/image/i1v8e59c3/

Scene is 2014 only.

[everyframe]

I think its function is slightly vague, or maybe I'm just not understanding correctly. Specifics on how it would be utilized would help dictate a method IMO
.

Either way, sometimes you just have to keep things simple... here's my take ;)

[grahamef]

You can actually constrain a null to a curve using the factory Constrain to Closest Surface compound. Just select the null and choose ICE > Kinematics > Constrain > to Closest Surface then pick the curve. After that you can use a regular constraint to constrain the effector to the null.

[McNistor]

Wow, haven't visited this thread for a while now. I'll check your solutions guys and thanks!