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Leg_3jnt_01 issue

#1

Hi guys

I’m seeking advice regarding the 3 joint leg setup that is part of the quadruped guide prefab.
When blending between 3 joint leg with the Full3 Bones IK value the joined pops right on 0.5 value and pops back in position on 0.51.

The weird part is that it only happens on the left side. I rebuild it manually and still happens if I duplicate Symperty it also happens … i simply can’t find the reason why

I also tested both IK Solver settings or to build it with Full 3 Bone IK default value 0. Nothing solves the issue. It always pops on the 50% blend value.

image
image1000×964 418 KB

edit:
I played around with the div joint values and removed them. without them, the pop didn’t happen with 1 it does. the problem is i cant remove the first on since i need to to preserve a proper knee join deformation. otherwise my “mechanical” joints would disconnect if 100% weight is only on one bone since the divider bone is compensating for the twist.

edit2:
nvm i imported the guide into a new scene and the pop did not appear on the right leg but still on the left even with the first joint having a div joint

1 Like
#2

Hello !
Just to give more informations about EPIC_leg_3jnt_01 (which has the same bug than leg_3jnt_01:

if the param leg_fullIK is set to 0.5, the joint chain will be stretched straight like here :

image
image779×698 19.9 KB

If i swtich the parameter full IK when the IK control isn’t at default pos, the controler leg_C0_roll_ctl will do a beautiful 360° front flip ! (sorry for the quality)

leg_3jnt
leg_3jnt1291×810 1.59 MB

Maya 2023
mGear 4.2.2

#3

I have a fix for this, but it’s very strange. I’ll try and come up with a working code fix for this.

2 Likes
#4

I actually thought I had a fix for this issue but I do not. It’s still broken. I’m not sure why this is happening.

#5

gimbleLock3Bone
gimbleLock3Bone827×511 1.07 MB

It looks like the ref that handles the 3Bone to 2Bone IK has a gimble lock problem. I’m not sure how to address this. Also adding the foot to the leg changes the glitch. So I’m not sure how to remedy the situation.

edit:

okay, I figured out a solution. I’m not sure how permeant it is but it seems to be stable.

you’ll want to add this line after this parent constraint is made in the 3BoneLeg

pm.setAttr(parentc_node.interpType, 0)

it will set the constraint to noFlip mode, which will stabilize the blend and correct the flip. I can’t think of another solution.