Hi, one of the things I've struggling a bit to understand are the different types of bones and when to use them. Is it correct to say that in the basic IK setup, the Thigh and the Shin are deformation bones and then foot is a control bone? As in this setup the animator only needs to move the foot and the leg will move along (and deform the mesh). But technically, the foot also deforms the foot mesh... And then the knee is also a control bone? In the rigs in the download section, are the control bones the ones that have custom shapes and are exposed (while the other, deformation bones, are inside the mesh and typically hard to see unless you enable "in-front")?
And finally what is a mechanism bone in practice?
Thanks!
Hi Mauro.
Let me see if I can answer some of your questions.
In reality all bones are the same in the software, we are just using them for different purposes to achieve a goal. (make the character do what we want)
It's best practice to separate them into 3 main categories.
Deformation bones - they will move the verts.
Control bones - the animator will animate them.
Mechanism bones - they don't deform, and won't be animated. But they are needed for the rig to do what you want.
You are correct in assuming that only control bones have custom shapes on them. As they are the ones the animator will use. All other bones can be hidden.
In the case of this exercise - we are just demonstrating the basic functionality of the IK system. This is not how you set up a real character (although some of the mechanism bones will have the ik constraint on them)
In a real IK leg, you would have a set of deformation bones that deform the leg (DEF-Thigh, and DEF-Shin, DEF-Foot).
There would be a set of MCH bones (MCH-Thigh, MCH-Shin and MCH-IK_target) This would be where the IK system lived.
Then there would also be a set of Control bones. ie - The Foot_IK and the Knee_target.
I'm excluding some of the other bones like the FK chain that the DEF bones can switch between (IK/FK slider). But that's a basic run down of things.
There's a follow on course from this one coming out next month. I hope you're not still confused by then, but this should help explain that setup above (with the extra parts though)
Hope this helps.
Hi Wayne, thanks for the explanation. Looking now at the VonnBots I do see clearly what you are explaining now. The naming convention does help a lot to understand.
But the newbie question I'm trying to understand now is why setting up like this is better? Sorry if I'm jumping into the other course in advance...
After the basic IK lesson I was trying to setup a simple humanoid animation and study some rigs. My initial thinking would be to have DEF_Thigh, DEF_Shin and DEF_Foot (deformation bones with the corresponding mesh and vertex groups). And then create a control bone to move the Foot and a control bone for the Knee. The Foot control bone would move the DEF_Foot (either using drivers or parenting). And the IK constraint would be in the DEF bones directly.
The DEF, Control and MCH setup looks like a Model View Controller model to me :). As I understood, the Control moves the MCH, that has the IK, that then moves the DEF that finally moves the mesh (and in reality there is a fourth one called tweak). But the part I don't fully understand is the reason/advantage for having the MCH bones.
Thanks,
Mauro
Hi Dwayne , Thanks! This is clear. I did not think about switching from FK to IK, but I do see the need to have multiple bones to be able to handle both