[Maya] Get the Angle of a Joint Chain (3 Joints)

bentraje

Hi, I'm trying to retrieve an angle of a knee bone. So its either 180 degress or less 

This has been discussed before in the following threads:
Here and Here

Unfortunately, all those matrix jargon is just way over my head.
Luckily, ThE_JacO (Cult of Rig) provided a demonstration of it in a screenshot. 
But I can't quite put it together since the parameters were not exposed. Basically, I can't figure out what specific value is plugged from the decomposeMatrix node to the plusMinusAverage node 

You can see an illustration of the problem here: https://www.dropbox.com/s/ugpsfpffq7ao8u9/MYA063_joint_chain_angle.jpg?dl=0

You can also see an illustration file here: https://www.dropbox.com/s/ag03n1ezow6xpel/MYA063_joint_chain_angle.ma?dl=0

As you might know, it is not working properly. My locator should have a rotation value but it only has zero. 

Is there a way around this?

Thank you for taking the time to look at the problem.

pasha_sevez

The connection go NOT into the same inputs ) Click plus sign and you'll notice that  Matrix3 in connected to Input3D[0] and Matrix2 to input3D[1]. Hope in makes sense )

P.S. On this graph you should have joint2.t - joint1.t in first pma and joint2.t - joint3.t in the second.

RN

There's a tutorial showing something similar (this type of node setup can be called a 'pose reader') on Vimeo, maybe it helps:
https://vimeo.com/album/3457150/video/64958089#t=3m50s (at 3:50)

bentraje

@pasha_sevez
@Greentooth

Thanks for the clarifying mate. I'm good for now

pasha_sevez

RN said:

There's a tutorial showing something similar (this type of node setup can be called a 'pose reader') on Vimeo, maybe it helps:
https://vimeo.com/album/3457150/video/64958089#t=3m50s (at 3:50)

Btw, helpful info - thanks! Always can learn something new