Skeleton "bone" dimensions/coordinates

Unity Engine
1

Hello all,

I’m new to Unity, and I’m trying to write a script that controls the skeleton of a simple humanoid. I’m trying to dynamically determine the dimensions (length) of each bone of a skeleton, and the coordinates of the joints.

I think I’ve got a pretty good estimation, by getting the difference between Transform.position of the limb, and the Transform.position of the child it is attached to.
Example:

Transform RKJ = ..; // right knee joint
float dx = RKJ.GetChild(0).position.x - RKJ.position.x;
float dy = RKJ.GetChild(0).position.y - RKJ.position.y;
float dz = RKJ.GetChild(0).position.z - RKJ.position.z;
float upper_leg_length = Math.Sqrt(dx*dx_dy*dy+dz*dz);

And I’m sure there’s some vector math that can be done with Vector3 objects mb like:

float upper_leg_length = deltaVec.magnitude``` 

But besides this optimization, is there a better way to determine the dimensions of individual bones?

Best regards,

Mikhail
2

To my knowledge there isn’t that information automatically available but I might be wrong. Most likely if there’s anything that would allow you to access that data, it would be found on this page:

Is there any reason why you are worried about the optimization? I would imagine that you don’t need to calculate scale of humanoid bones every frame, as the limbs are of same length, so their dimensions don’t change in that sense?

3

Thank you for your reply, looking through the Scripting API right now, including AnimationModule, so far haven’t found anything better.

With regards to optimization - I’m using Unity for 3D visualization of some kinematics rather than programming a game. I plan to implement muscles as soon as I figure out the skeleton, and muscles have a tendency to change length.

EDIT: I should probably add - Mecanim/Animator might be what I’m looking for, but I haven’t figured out exactly how to attach my model to Mechanim, and until I do, I can’t say for sure that it suits my needs.

EDIT: I still can’t find any way to control the bones and muscles through Mechanim/Animator. Seems like if I link my rig to the animator, then the physics are controlled by Mecanim, and I lose the ability to modify the kinematics and physics the way I want.