Search Unity

  1. Welcome to the Unity Forums! Please take the time to read our Code of Conduct to familiarize yourself with the forum rules and how to post constructively.
  2. Unite 2023 Registrations are now LIVE! We are thrilled to announce that Unite 2023 Registration is now live and open for all!
    Dismiss Notice
New Forum User Notice Unite 2023 Registrations are now LIVE!

Question Animation rigging for Inverse Kinematics

Discussion in 'Animation' started by Ominos_Amethyst, Oct 27, 2022.

  1. Ominos_Amethyst

    Ominos_Amethyst

    Joined:
    Dec 15, 2021
    Posts:
    10
    Hi everyone!

    I'm seeking help about the animation rigging package and Inverse Kinematics. I've read a lot of Unity's own documentation about the package and seen a lot of tutorials on youtube, but I can grasp the idea to make what I want to work with the package.

    I have a "leg" (image attached), and I want to move the tip and make every other bone move (IK) in just 1 axis (Constraint). However, I don't fully understand how to achieve it.
    Keep in mind: there is 1 bone that is not visible, it is the tip bone at the far left of the picture.

    Untitled.png

    I know we have the following constraints available for us:
    However, I don't know very well how to utilize them to achieve what I've describe above.Nor do I grasp the concept of adding multiple constrains for 1 leg.

    I did tried to use Two Bone IK Constraint, didn't work, given that my legs has many more bones.
    I also tried to use Chain IK Constrain, it did work, but I was not able to find a way to constrain the rotation axis for each bone.

    Any help in this matter will be extremely appreciated!
     
    Ominos_Amethyst, Oct 27, 2022
    #1
    brainwipe likes this.

  2. CodeKiwi

    CodeKiwi

    Joined:
    Oct 27, 2016
    Posts:
    119
    I had a similar issue a while ago. I wasn’t able to solve it with the built in constraints and ended up making a basic custom constraint. I think I broke it up into two steps.

    Step 1: distant to target.
    • Two poses (min / max leg distance). Could be a masked animation clip or maybe min/max values for each x axis joint.
    • The lerp value from min to max must always increase the distance e.g. each lerp value should be unique.
    • Given a target IK distance find the lerp value that matches this distance. Could use a lookup table or just calculated at runtime. I’m sure there are better formulas but I just take the mid point a few times e.g. lerp 0.5 (less than target) => 0.75 (greater than target) => 0.625 etc.

    Step 2: aim / look at the target.
     
    CodeKiwi, Oct 31, 2022
    #2