Hello there!

I'm working on modelling/rigging props for my next short animation and I ran into a snag: What would be a reasonably well done way of rigging a backpack strap - i.e. the ones my character will pick that backpack up and put around his shoulders..?
I have a model tha has a belt (i.e. flatened cylinder) creating a loop there and have created some cross sections for it to bend a bit. Bit I need a few pointers as to how to set up bones to suppor the animaion. I don't want the straps to look like they are "cast iron"...
Anything that saves me from hand-animating every control point is helping.

Thanks in advance,
Atkelar

See the thread about guitar straps
http://www.hash.com/forums/index.php?showt...mp;#entry331917

Can you show what it looks like, including a wireframe?

Hello!

Here's a wireframe of the straps/belts or whatever you might call them. I didn't include the "backpack" because it's part of the main joke in the animation and I don't want to give away anything.

Click to view attachment

I'd like my character to pick up the backpack - either AT the straps or at a handle and then put it on. Either way the straps have to act like leather belts - i.e. somewhat stiff yet still bending in all directions - and I'd like to spare myself the time of hand-animating them in muscle-mode.

Hope that clears things up a bit and again, thanks for all the input!

Atkelar

Interactions with solid objects are hard. Semi-solid objects are even harder.

It's not un doable. First, I think you can simplify the splining by removing most of the spline rings and just leaving the ones at the major bends.

A path constraint for each strap would be the way to go, I'm thinking.

Hope that helps.

Hello! Sorry for the dely - RL keeps interfering
I used that many CPs for a reason: Splines bend, but only between CPs - in case of the "semi-solid" objects that means: less CPs, more rigid. Or: more CPs, more "dangly straps" (IF I manage to rig it right )

Thanks, Atkelar

I'm not sure how a path constraint would help, because the path constraint I'm familiar with is used to constrain one bone along a path. I'll take a look at the constraints in the evening, maybe you are referring to something else or the path constraint has a different option.
Or - maybe - I'm still not making myself clear enough (sorry, English is my second language only ) - I'm not looking for a constraint to "stick" the strap to the hand of my character, that's something only relevant for a few frames and could be "hand animated" without much efford. BUT the straps need to move during the interaction and I woul like to avoid muscle mode and moving dozens of bones for this...

Greetings, Atkelar

It depends on the finished look that you are after. If the straps are going to be very simple and you don't mind the textures stretching you can make the parts of the straps that are in contact with the body a part of the body and just constrain them as local geometry. They can be modelled as part of the torso or a separate model. The parts of the straps that run between the backpack and contact points on the body can simply stretch with the movements of the body and backpack.

This video shows a similar strap rigged with a path constraint (actually, a single path with a bunch of path constraints), Atkelar.

Hope that helps.

What I would try is something like this: Create a bone for each spline ring. Create a simple spline path with only 4 or 5 cps. Constrain the bones to that path, assign each path cp to its own bone. Hide the bones for your original rings. Not totally sure this would work, might require more constraints. The other option I'd try is a bone reduction system similar to the Ol' Bendy Legs tutorial: http://www.garycmartin.com/octopus_setup.html That way you can reduce the amount of bones needed to animate to a number that you're comfortable with, and you'll get smooth curves.

How close are we really going to see this strap? What's actually going to happen in the shot?

I'm trying to think of a case in feature animation where something like this gets real up-close attention. Is there one?

Here's how I imagine a simpler strap working. Minimal bones needed, the splines still curve smoothly.

Click to view attachment

i think you can use more bones and also a constrain

Wow! That would be exactly what I was looking for - except it doesn't say how to actually set the constraints and I still can't imagine how the path constraint would work togetern with the nulls...

Greetings, Atkelar

Of course - - the basic design decision for "Frucosiadas" was: very simplified yet well animated. So besides the key character(s) of a sequence there will always only be the key prop(s) and no "set decoration". So: the "backpack" in question IS the key prop in my next sequence and it should look smooth.



Thanks for the input - I can actually picture this working in another sequence (where the backpack is only worn and not put on/off) but for the current one I'll try to duplicate the rigging in the other video!

Greetings, Atkelar

I deleted the quiver from the model shown in the video because it is Steve Shelton's model for a project he's working on...I don't mind posting the rig though. I left the strap so that you can see how the rig works, but modified it to be more generic.

Hope that helps, Atkelar.

Thank you! I had trouble setting up te "ease" setting - but it might be that I created the bones as hierarchy instead of independent ones... I'll try this again in the evening!

Greetings, Atkelar

Thanks again! I was able to reproduce the rig and it works like a charm! well... now for the left strap... I think it's time to try out that mirror-bones plug in.

Greetings, Atkelar