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Bug Twist chain constraint - Initial chain shape not maintained when root has non zero rotation

Discussion in 'Animation Rigging' started by SylvainChague, Jan 12, 2023.

  1. SylvainChague

    SylvainChague

    Joined:
    Nov 20, 2012
    Posts:
    8
    Hello,

    I found an issue with the twist chain constraint of the animation rigging package (version 1.2.0, tested with Unity 2021.3.9f1).
    In the attached scene, the default sample scene has been modified so that the chain has initial non-zero rotations.

    If the root of the whole hierarchy has no rotation (left model on the images below), the constraint work as expected. It preserves the initial chain shape and follows the constraints correctly when entering play mode (right image below).
    However, if the root of the hierarchy has a non-zero rotation as the right model in the images below (33 degree rotation on the Y axis), then the initial chain shape is no longer maintained.

    I guess there is something wrong in the way the initial chain shape is computed or applied at runtime...

    The scene is attached to this post.

    Twist chain issue.JPG
     

    Attached Files:

    bart_artanim likes this.
  2. NullQubit

    NullQubit

    Joined:
    Jun 1, 2015
    Posts:
    11
    Did you manage to find a fix or workaround to this? I'm having the same issue where my multi-aim constraint is not working as expected because imported fbx models from blender automatically apply a -90 degree x rotation to the root. If the root is not rotated, then it works fine.