I have been working on a character rig that requires the character to hold a weapon in either hand. We are able to get the Weapon attachment points on either hand. Now, I am setting up a constraint that allows the characters left or right hand to be constrained to the hand guard/barrel of the weapon. It works on one side of the character and not the other.

My process to lock the right hand to the hand guard/barrel of the weapon is: Select the R_hand_bone_auto null, select Blend, Simple, RX RY RZ, select Target Object which is a Null (L_Weapon_Attach) placed at the point of contact, Select Enter. I also do this for the R_arm_bone_goal_auto, instead I use the TX TY TZ values. Then I setup an additional IK Space Switch for the L_Weapon_Attach.



This works perfectly, and now I try the same process just reversed with the Left side. This time I get a CHOP error that I just can't figure out. I have tried starting with the Left side instead of the Right and still the same error.



I did try building the Constraint network manually and still the same errors. I have also tried to recreate the three nulls for the L_hand, and no errors have appeared. When I try to constrain the L_hand_bone to the L_hand_bone_ctrl the hand loses all function. Does anyone have an idea of what this error could mean? Thanks!

can you attach your file?

goldfarb
can you attach your file?

Hi Michael,
I sent you a message with a link to the HDA. I can't post it on the forums at the moment. I have some limited info on versions in the Help Section of the HDA as well.
Glen

I got the scene from Michael and had a quick look. There is an evaluation cycle when you add the second constraint. I think it comes from the constraint installed on L_arm_bone_2 which pulls from L_hand_bone_ctrl. The solution might be to add new OBJ nodes to prevent the cycle or to use a Fetch CHOP node instead of using a CHOP_Object node.

Guillaume
I got the scene from Michael and had a quick look. There is an evaluation cycle when you add the second constraint. I think it comes from the constraint installed on L_arm_bone_2 which pulls from L_hand_bone_ctrl. The solution might be to add new OBJ nodes to prevent the cycle or to use a Fetch CHOP node instead of using a CHOP_Object node.

Thanks, I'll give it a try!

@Guillaume The Fetch Chop worked well in the L_arm_bone_goal_auto and L_hand_bone_auto. I had to use a Transform VOP to reverse the translations that I needed.

In the end I actually went a different direction. I added another Object Offset to the Parent Blend lock the L_arm_bone_goal_auto to the R_Weapon_Attach null that is located where the hand holds the barrel of the weapon.

I used a Look At Constraint for the L_hand_bone_auto to Look At the R_Weapon_Attach. This gave us the rotations needed to keep the hand on the barrel. Then we just have to fine tune the hand animation instead of creating a brand new animation for the entire L Arm and Hand.

Thanks for the help!