I'm using the Cats plugin to optimize this character model for vrchat! Unfortunately, getting eye tracking to work has been rough.

The error message from Cats.

[Update 2022-5-30: This Cats feature is apparently deprecated! I still needed this question answered to get the eyes rigged though]

I tried using a Track To constraint to get the Eye_Master bones to track the Eye bones, but now the eye rig is broken and the bone seemingly avoids being clicked on. I really don't know how else to describe this.

The bones flailing around.

I'm sorry this post is relatively vague, but when it comes to character modelling, rigging is what I'm least versed in.

You can find the .blend file here. Thanks again!


1 Answer 1


The track-to isn't working right because it is involved in a dependency loop.

Eye_Master.L is set to track-to Eye.L. But Eye.L is a child of Eye_Master.L. So the rotation of Eye_Master depends on the location of Eye, which depends on the rotation of Eye_Master, which depends on the location of Eye, etc.

You have to choose whether you want Eye to be controlled by Eye_Master or if you want Eye_Master to be controlled by Eye.

  • $\begingroup$ Thank you so much! I can't get this to work with a Track To constraint, but I can get it to work with a Damped Track constraint. This isn't a problem, but I'm curious as to why this is. I've made a video to demonstrate. $\endgroup$
    May 31, 2022 at 1:28
  • $\begingroup$ In your video, you have already unparented Eye.L, different than the file you've provided; a damped track certainly will not work right if creates a dependency loop, no better than a track-to will. The reason the track-to doesn't work in your video is because you cannot use the same track axis as up axis (and the up axis is really +-axis.) If you want a track-to with an unparented Eye.L, set the track axis to Y. But this is really a brand new question-- the problem in the file you gave is a dependency problem. $\endgroup$
    – Nathan
    May 31, 2022 at 3:52

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