New to Animation Editor: Inverse Kinematics (IK)We are happy to announce that the Studio Animation Editor now supports Inverse Kinematics (IK) on R15 rigs! Unlike Inverse Kinematics in other animation suites, the Studio Animation Editor does not use Inverse Kinematics at runtime. Instead, all of your transformations done in IK are baked directly into the keyframes of your animation. This feature is still experimental and is entirely optional. We would love to have your thoughts and feedback on anything that can be done to improve it!
What are Inverse Kinematics?In the context of animating characters, Inverse Kinematics will use a physics solver to determine what rotations a group of joints should have in order to get a specific joint to a desired location. This is very useful for something like a walk cycle, where trying to move the foot joint upwards would cause the upper and lower leg to rotate so that it appears that the knee is bending. This would be cumbersome in Forward Kinematics (the default mode when starting up in the animation editor), as you would have to directly rotate the upper and lower legs yourself in order to get the bending motion.
Requirements for using IK in the Animation Editor: Your rig must be an R15, and it must have the proper joint naming conventions (see under the R15 diagram here: https://www.robloxdev.com/articles/r6-vs-r15-avatars). Also, any attachments between parts must have matching names. For example, an attachment named “LeftWristRigAttachment” exists for both LeftHand and LeftLowerArm. If all of the requirements are met, an “Apply IK” button will appear next to the model name in the Animation Editor.
How to UseClick the “Apply IK” button in the Animation Editor and you should see a notification appear in studio saying that IK has been applied to the joints.
Make sure that your manipulation mode is set to “Move”. You can change manipulation modes in the animation editor by pressing “R”. You can now grab any part that you want, and translate it. The IK solver will try to rotate any parent body parts in order to get that joint into the position you wanted. If you switch to “Rotate” mode, this will also attempt to rotate the part, however, the rotation will be limited to whatever is set on the physics constraint.
IK ModesThere are two IK manipulation modes that you should be aware of, Body Part and Full Body. You can change these modes via the IK dropdown.
Body Part ModeThis isolates movement to specific limbs. For example, moving the Right Hand will only affect parts that compose of the Right Arm (RightUpperArm and RightLowerArm).
Full Body ModeThe IK solver will consider all joints when moving a specific part. In order to exclude specific parts from the IK solver, you must pin them.
PinningPinning a joint will make the body part immovable during the IK manipulation, but only if it is not the part that you are manipulating. An example of this would be with the feet. If you pin both feet, they will remain stationary when manipulating other joints, which could cause a leaning motion on the body.
However, you could still grab one of the feet directly, and in this case it would move.
You can pin a part via clicking the pin icon next to the part name.
Overriding KeyframesWhile in the Forward Kinematics mode, you may have made certain transformations that would normally go outside of the physics constraint limits that the IK solver uses for that part. When going into IK mode, the Animation Editor will ask you if you would like to correct any keyframes that have transforms outside of these limits. This is completely optional! We do warn that this can be a lengthy process for more involved animations, and you will not be able to make any edits to the animation or play it back while this corrections are taking place.
Returning to Forward Kinematics ModeThis is the default mode when you start up the animation editor. In order to go back to this, click on the IK dropdown and select Remove IK. This will not remove any manipulations that you have done in IK, that data will still be stored in any keyframes that you have made while IK was applied. This simply removes the constraints from the rig and allows you to manipulate the parts without the IK solver.