I'm animating a logo for a friend. The original logo consists of simple pen or brush strokes. The "arms" are the handle and spout and the "legs" are just two zig-zag strokes. This should be easy to rig and plenty of squash-and-stretch is spot on for this type of character. A picture of the logo is attached.

I'd like to use the TSM2 rig, but the challenge here is that the "hips" and "shoulders" will be offset by 90 degrees (hips side to side like normal characters, but "arms" fore and aft like the coffee pot it is). Since the the various parts are abstract and not actually connected, I'm hoping I can set it up in a normal T pose, then rotate the arms and "body" of the pot (including the spine). Any thoughts?

Actually I think the legs might be better rigged differently than normal legs. What I'd like to do is have them just follow the contour of the bottom of the pot rather that be hinged to it. The end closest to the pot should stay close to the surface (with a small gap). The rest of the zig-zag would stay more or less "normal" to the surface and would stretch or compress along that normal direction. This could be a classic use of the surface constraint. I could use an aiming bone to control the position of the leg and it's angle relative to the surface tangent. I could use a target bone to position the other end of the zig-zag and the aiming bone (by aiming the aiming bone at it, of course). Then just stretch to reach the target and at tweaks to keep the volume constant.

Any suggestion, advice would be welcome.

Bill Gaylord

TSM2 should be able to do either method. TSM2 rigs the geometry bones wherever you put them.






Rig the legs with TSM2 "arms". The shoulder bone would provide a pivot that lets you move the origin of the "leg" to anywhere in a radius from the center of the spherical bottom of the pot.

You can add an extra set of arms with the TSM2 parts tab and delete the default legs before you run Flipper and Rigger.

Thanks! I'll give it a try.

Anybody out there have experience using a surface constraint? I thought I understood how to set it up, but apparently not. In this coffee pot character I wan't the "legs" to follow the surface of the bottom of the pot, though with a visible gap. Since the bottom is not exactly spherical I'm thinking the surface constraint will do the trick. I just can't seem to get it working. The picture bellow shows the gist of what I'd like to do, simplified a tad until I get the surface constraint figured out. The bone constrained to the surface will be the one used as the "hip joint" for the leg--sort of. This is a very abstract character after all.

Can you explain a bit on how you are trying to set this up? This should be fairly easy to do. Can you possibly post a project or model with your setup? I could take a look tomorrow.

As the limbs of this character are not actually joined to the body I don't think you need to consider surface constraints. Of course this depends on how far you intend to deviate from the actual logo in your character design. I guess if you are thinking about using a distortion cage for the body then surface constraints might be the way to go.

Here is a very crude example of a simple rig but I think you have something in mind which is closer to the teapot characters in Beauty and the Beast.
Click to view attachment
I'm sure that TSM2 would handle it but I think a custom rig might be better.

Actually I don't want the legs to be jointed to the body. The original logo should give you an idea of what I mean. It's a lot like the thigh bone of a hampster being almost completely hidden in the fat and skin around it--makes the knee look like the pivot point even though it isn't. In this abstract case I wan't the "leg" to float the same distance from the pot, yet I want it to swing along the radius of the pot, as though it were the knee joint of a hamster. The pot is not actually spherical, so a bone rotation won't keep the leg floating the same distance from the pots surface--hence the desire to use a surface constraint.

Surface constraints work just fine for what you are trying to do. As I said, I need a bit more info on how you set it up.

Here's a demo of the surface constraint.

Click to view attachment

Animate "Shoulder Pointer" to move "shoulder" around the surface of the non-spherical mesh. I presume you would constrain your leg to hang from the "shoulder" and animate it from there.

Yes, that's what I'm after. I forgot to open the pose slider view to turn on the constraint pose. Obvious booboo.

Now I need help making sure the bone is constrained to point either normal to the surface or at least some predictable direction. When I apply the constraint, the bone acts like a bit of iron stuck to a magnet, but doesn't necessarily point the way I want it to. I'd like it to keep the leg facing forward unless I deliberately want the knee to rotate outward, so I suppose I need to control the roll of the hip bone. Most of the time I'll just want the legs to follow arcs in vertical planes offset from the center plane. Other times I'll wan't to rotate that plane so the leg swings in a tilted arc toward the side, as he might do in a karate kick.

Once I have this worked out, the next thing will be rigging the legs themselves. I want the joint action to be very rounded, the upper gradual curve being the knee and the lower one the ankle, where each curves or straightens rather then bending sharply at an obvious joint. I know cp weighting could do this, but I've noticed that the spline rings can tend to compress into elipses. I suppose cp weights could do most of the work, while some smartskinning could tweak out the distortion.

Not sure why I wind up animating such unconventional characters...I should practice rigging and animating some more conventional characters for a while.

Thanks!
Bill Gaylord

Here is a very crude animation. It shows the gist of what I want to do. Need to add refinements to how the surface constrained bone is controlled. I need to learn better what determines the surface constrained bone's orientation and how I can better control it.

Aha! That looks good!

Now I need to sort out the legs themselves. I'll experiment a bit. You can see the basic shape of the "legs". I want to avoid an obvious joint. I think a simple stretch and compress type of action would work best, where the "S" shape straightens out or curves tighter, or each curve independently.

Heres what I'd like to accomplish with the most efficient setup I can manage to get the desired result. Any suggestions? In the animation I'll have to match the final profile of the logo itself in a "freeze frame"--running pot, snap shot, transition to actual logo. I figure I'll need to tweek the actual shape of the legs to match that profile. The 3D leg shapes will have to be tweaked to account for camera view settings, the angle of the leg relative to the camera view, etc. Looks simple, but I have a sneaking suspision that it will take a fair amount of planning and work.

I think it might be wise to be able to scale the individual spline rings of the legs, handle and spout, even though the controls might be complicated. It would make tweaking the silhouette to match the log a lot easier to manage. Once that view is tweaked I can lock down the scaling and then animate normally.

Interesting how an abstract character can complicate things!



Sorry, the JPEG compression almost completely blended the text into the background. Expand it to full size and it should be readable.

It is doable, but first... does it really need spline rings?

Click to view attachment



two may be not enough , but 14?

Fewer rings is something I am considering. More rings gave me some more control over the outer contour, but I'm sure fewer can get the same result. Fewer longitudinal splines, too.

oops, that should have been "does it really need 14 spline rings?"



How far does the leg have to bend from that original position?

This original position is likely to be one extreme. The other would be almost straight. I'm thinking I may not neen conventional leg bones even. Just a control to straighten/stretch the leg or bend it into a tighter "s" shape. I doubt I'll need to wiggle the "toe" separately.

I do want to be able to scale the spline rings so I can match the silhouette of the logo in the "freeze frame".

My initial inclination would be to model the leg straight and rig it so it can make that S-shape, rather than model it S-shaped and try rig it so it can straighten.


But it has to be that exact S-shape I suppose...

Actually, I think if I get close to the same silhouette it will work fine--doesn't have to be exact. There will be enough action to provide some sleight of hand if I time the transition to the 2D logo right. I'm thinking that Smartkinning it with a straighforward three bone leg structure would probably be best. If I can control child bone position and orientation in a Smartskin I'll use that to control individual spline ring bones. In separate pose sliders I'll scale each spline ring bone and hence the ring itself. Then I can match the silhouette to figure out what the scale of the rings need to be.

Used fewer spline rings, assigned "spline ring bones" to intermediate rings, and fan bones to the rings at the leg joints. Then adjusted the position and rotation of the intermediate spline ring bones with Smartskins on the Shin and Foot bones. This should also allow me to scale the size of each ring with a pose slider for each intermediate and fan bone associated with the ring. Easy to set up and does the trick!

Thanks for the help so far, folks!

Added two more rings. I think with some tweaking this will look smooth. I'll add scaling of the rings later. I think walking and running will be pretty easy with this. I should be able to just vary the curl of the overall "s" shape with a simple pose slider; point the leg with one target bone (and rotate it with the roll handle of the parent bone that orients the leg); and direct the surface constraint pointer bone with another pointer. Very simple rig! Maybe even use only one target.

OK, experimenting with surface constraints it looks like by default (at least in 15.0) the constrained bone is oriented such that it's roll handle and z-axis stay in a tangent plane to the surface. The direction of the bone in that plane will rotate with the roll of the pointer bone. (I didn't check to see if it automatically orients opposite the roll handle or not. Need to check that.) Is this the default behavior?

I'll set the leg bones to be children of this bone, so this should be a very simple rig!

Whatever it did if you didn't invoke the Use Offsets button would be the default. I haven't tried it lately.




And since they are children of that surface constrained bone you can animate them to undo anything unwanted that the default orientation of the surface constrained bone creates.