Rigging Characters that have props?

[GregO619]

So, I am still really new to effective rigging and the ways of animating characters in a puppet like fashion. My dilemma is that I have this character holding a guitar. So, one arm is in front and the other behind. I would like to create a single skeleton rig, but don't want the guitar to get distorted when I move the arms or torso.
Any suggestions? I am sure I am not the first to ask this, so links or other discussions to get me going in the right direction would be appreciated. Attached is a jpg of the character with the guitar.

[Greenlaw]

Try adding a bone for the guitar and use Use Selected Bones for Flexibinding. Using this method should hold out any deformations from other bones in the rig. Alternatively, you could bind the guitar layer to a single 'guitar' bone. Naturally, this assumes the guitar is a separate layer of art.

Fun character by the way.

[GregO619]

Thanks, I will have to give that a shot. Also, thanks for the character compliment. Figure since I am not tattooing full time anymore I should explore some old passions that are digitally more accessible these days. I used to do a lot of work in Director back in the 90s and early 2k's. Stopped writing code, but never stopped drawing. Thanks Again!

[slowtiger]

I'd put the guitar on a separate level and use Laye binding since it's a rigid object. The bone for the guitar should start at his left shoulder: that's the point where the shoulder strap would begin if you'd draw it. Rigged this way, the guitar will swing naturally from his shoulders while the hands can freely play around.

[heyvern]

If you have v10, rigging the arms to the guitar should be a piece of cake with the aim bone constraint.

A long time ago I was trying to rig the exact same thing. A character playing a guitar. With the standard, "9.5" bone constraints it was very difficult to get both hands linked to the guitar.

Now with bone targets in v10 this can be done so easily.

If you have v10 and can use the target bone constraint, I would suggest a three bone rig just for the guitar. The guitar would still be bound to only one bone. The extra two bones are only for targets for the forearms (not the hands).

You have one parent bone that the guitar is bound to. On ether side of this parent bone are the two bones used to target the forearms. This way, you can control how the hands move on the guitar and they stay connected to it. So the guitar "neck" bone could be translated to move the forearm/hand up and down the neck of the guitar. The same with the other hand. By moving the target around it stays "connected" to the guitar but can still be moved. Both guitar bones are parented to the guitar "root" bone. You can move this bone to move the entire guitar along with the hands attached to it.

Also, with the forearms targeting the guitar, the hands are separate from the guitar you can rotate them for, strumming, fingering on the fret etc etc.

When I saw this new feature.... one of the first things that popped into my head was the CRAZY guitar playing rig I had to create to make this work. Now it's like.... a 5 minute job to rig a character playing a guitar. It's sooooooo easy.

anime-stuido-pro-v10-guitar-player-rig

[GregO619]

Right on! That is exactly it. I just got v10. But haven't spent a lot time with it just yet. But that's about to change. Appreciate all the help. Hopefully I will have some progress to post in a week or two.
Thanks again for all the help.

[heyvern]

I am going to explain a tiny issue when using target bones that I've encountered. This bit of info may save you some time and trouble.

When you use a target bone, like I did for the forearms, if you drag only the target bone, the aiming bone will always... always always always... (did I say always? ) bend in ONE direction. Don't even both trying to make it bend in the opposite direction by dragging the target bone. it just won't bend any other way.

The angle that a targeted bone bends is based on the frame 0 angle (or a rotation key in the timeline). The "IK Solver" for a target has to "pick an angle" to bend to reach the target... it's all really complex funky math that will make your head spin (I prefer visiting Colorado to make my head spin). The IK solver uses the path of least resistance so if the bone is rotated a tiny bit off 0 angle on frame 0, that's the angle it will always bend to reach the target bone. Even if the bone is EXACTLY 0 rotation it STILL has a "preference".

When I did this originally during target bone testing in beta, that arm just would not behave. It looked great to start, but then when I dragged the target past a certain point the elbow would bend the bicep backwards and look absolutely ridiculous. Like one of those bizarre yoga masters playing guitar.

To change the direction of the bend, like I did in the sample file, you have to "force" a rotation key on the aiming bone (the forearm). Normally angle keys on a bone with a target will not do anything because the rotation is controlled by the IK targeting of that bone, however if you drag it "really hard" in one or the other direction it will "snap" to the opposition angle rotation. This is sort of like how bone locking works. When using bone locking sometimes a bone won't bend correctly and you just force a key to pop it back into place. It's not as simple for target bones as it is with bone locking but still works with some "fiddling".

You can see this "pop" on the "fret" arm as it slides up and down the guitar neck. You can see these rotation keys of that bone in the bones rotation channel in the timeline. The forced rotation doesn't line up exactly with the "pop". This is because the bone is rotating between two keys so the "pop" doesn't happen exactly where you put the forced rotation keys. You will need two keys, one to bend one way, and another later if the target slides back.

I added in the first forced rotation key and then had to slide it up and down the timeline till I found the perfect spot where the "pop" wasn't very visible.

-----

There is another, better way to get around this, but it's more tricky and requires an extra target bone for each arm. It's a "non standard" type of rig and also has other quirks to deal with but it does allow absolute perfectly smooth movement of bone joints that are targeted. You drag the forearm bone to move the elbow joint. This is why it's "non standard" because normally you wouldn't have position keys to rotate bones.

When I have time I can post the other version.

[Greenlaw]

Thanks for sharing your technique!

It reminds me of what I had to deal with when I was rigging the 3D characters for the Brudders music video project. To capture the motion data, I mimed playing the ukulele using a Nerf sword as a stand-in because it's necessary to minimize occlusion from props as much as possible. When the motion data was targeted to the Toullie rig, the paws did not fall anywhere near the cg uke because a scale prop was not present when the motion was captured. To get the paws in proper position, I applied a technique similar to yours, essentially constraining the paws to the uke but only along certain axis so that I could preserve the strumming and fretting motions.

Anyway, I thought it was interesting how the tools ASP are becoming more and more like what's available in the 3D programs I'm used to working in--except in 2D of course.

G.

[GregO619]

Wow, Thanks for all the info. I think I need to try this with more of a front view character. My current character's perspective is being really uncooperative for rigging for whatever reason.

But all the advice is great. I think I may have jumped into the deep end too soon.

Thanks.

[Greenlaw]

Oh, one more thing: in the case of the Brudders excerpt, I had to parent/constrain the ukulele to a bone attached to Toullie's lower spine--this gives it a point to pivot naturally from, and it allows the paws to be both constrained and to move/slide independently along/over the different parts of the instrument.

G.