Moho Animation Forum

I am building a 'Body Turn" bone that turns my rig from front view to 3/4 view.
How do I flip my IK so the foot can point in the opposite direction??

Ex. left foot needs to point right when the body is in the 3/4 Right pose.

Details: IK created on the foot bone to constrained to the ground using a target bone.

Here is the current set up:

I'm guessing you're using Independent angle on the feet to keep them looking 'planted'? If so, that's a completely valid technique, however, it does mess up bone flipping with IK. The reason is that bone flipping doesn't mirror the foot bone when using Independent Angle.

To work around this, you'll need to keyframe the foot bone's rotation just before the flip, and then rotate the bone to the proper angle after the flip. It's a little annoying but not too much trouble.

Tip: you can make the flip look smoother by scaling the foot bone 'shorter' during the 'turn', and then scaling it back to full length after the turn. This creates the illusion of foreshortening. You only need this for one or two frames. It's a subtle effect but your brain will sense it as smoother animation. If you want to take it another step, use the foot bone's rotation to slightly angle the foot down during the 'turn'. This can help make the foot look like it has some depth.

Here's a quick example:



You might also have noticed that the leg straightens slightly in the turn. This not only gives the animation a little more life, it helps the foreshortening effect as the knee 'points' to camera.

I'd like to add that, while it's technically possible to put all this inside a Smart Bone Action, I don't recommend that because you'll be giving up some freedom with the rig. It's up to you though.

That is exactly what I want to do! Thanks so much DR! You're awesome! That example that you provided is exactly what I hope to achieve.

And to answer your questions, yes, I am using 'independent angles' on the feet.e
' on the foot

OK- I think I follow you, but I have follow up questions to clarify:

Step 1. Animate frames leading into the flip.
***TIP: Use scale to help with the 'foreshortening' look.
Step 2. Flip the bone: Q: How do I flip it?
Step 3: Animate frames after flip to help as well.
***TIP: straighten leg out to have it point to the camera.

I understand most of it except for the flip itself. Ex. Do I scale to -1? Do I use 'End flip'?? Do I turn off the 'independent angle'? Etc.

Thank you again, DR!

Sorry, I left out one part. I'll show the project to illustrate:



I have the 'Thigh' bone parented to a Flip bone. This bone should be used to move and flip the Thigh bone. The Thigh bone should only rotate (usually handled by the IK.) Set the Flip bone to be 'Ignored By IK' under constraints. In a full rig, the Flip bone is parented to the Root or Hip bone, not the 'Thigh'

To flip the bone, select the bone and click the Side Flip button (the second one in the pic below).



This will create a 'side flip' keyframe for the bone in the timeline.

I can upload this demo scene later but it will have to be after work.

That works perfectly! Thanks so much, DR! Your knowledge and graciousness are a massive asset to this forum. Thanks a bunch for taking the time to solve this and walk me through it. It is so greatly appreciated!!

Oh, one more thing: The reason the Flip bone is inverted is so the pivot point will be in the same position as the Thigh bone's pivot point. This way, when you move the Flip, it will be the same as moving the Thigh. (You don't want to move the Thigh bone because that will offset it from the 'flip' axis.)

Here's the file for the demo described above:

boneFlipDemo

This is a very simple setup (no point animation or actions used) but I think it illustrates the idea.

FYI, when you're using point binding for the foot, the orientation of the foot bone doesn't matter. For example, in many of the Moho rigs I build at work, I often have the foot bone pointing straight down vertically. This way, it can angle the bone 'up' for the left or right side and the foot bone doesn't need to be flipped when animating a 'turn'.

Hope this helps.

Thank you very much, DR! Looking through your example rig has been very helpful.

Foot pointing down: that sounds like a very smart idea. Just to clarify, the bone points straight down- but the foot artwork is 90° to it?
Below is a quick sketch I did on what I thought you did- is this accurate? If so, are the feet turns just animated by hand (points)??

Yup, that's it. This works when the foot drawing is for front, back and 3Qtr views too. Pointing down is a good 'neutral' position for any foot angle.

Thanks for clarifying, DR! I will try that on my next rig.

A side angle foot bone can be useful if you also need a toe bone to angle the toe.

That said, I usually animate the toe bend by switching to different foot drawing in a switch layer, or I animate the points in the foot drawing using a 'toeAngle' SBD. Sometimes, I'll do a hybrid of both techniques. It really depends on the character design and the style of animation required by the production.

Simpler, faster, and not 'crappy' usually does the trick, but finding the right balance is not always easy.

Have you ever posted one of your rigs online, DR? It'd be awesome to study one and see how you set one up.

Most of the rigs I create are for TV shows so I can't do that.

But I'm thinking about putting some personal stuff out there as examples for an online class. That project is still a ways off though.

TV: Makes sense that you cannot post them. I was reviewing the screenshots of your Puss N Boots rig and it looks like a robust rig. Looking forward to your class. I will be the first to sign up once you launch it.

Thanks again, DR!