Complex mouth rigging + Added in some animation smears.

[For context, this is an avatar I made for a client some time earlier... this year?-- _{How does time work...} yes, this year (2024)--anyways, I made it in live2D. For the uninitiated, it's the current major alternative to making 3D vtubing avatars that use face tracking.]

Since [I was asked on cohost] how I did it, I'll just do a quick breakdown here.

The mouth is made of three layers: the line for the top lip, the line for the bottom lip, and the mask for inside the mouth (which the tongue is clipped to).
If you use the deform path tool to draw a path while multiple meshes are selected, it groups those meshes together so that they all move together. It's pretty difficult to get everything to behave the first go round, and your mesh needs to be set up in a particular way, which is why the mask for the mouth has very limited geometry in a sort of zigzag pattern so that any vertices in the middle wouldn't get left behind. This geometry can be further subdivided later, but it works best fairly low poly to start with.

I basically just drag the corners of the mouth in so that the geometry collapses in on itself to be really small. I use both the deform path and also the temporary deform tool to collapse the faces pretty tightly.
So the widest mouth has the full geometry, the mid-sized one has the outer two lines collapsed in to the corners of the mouth, and the smallest one has the next two lines collapsed in.

Usually this can create a "tearing" effect on the exported model (where the smaller faces are collapsed, the more white bleeds into low opacity or anti-aliased faces), so sometimes I cover the collapsed geometry with another mask, but it can probably also be minimized using vtube studio's "get rid of white outlines" feature.

There's also still a bit of cleanup required since the deform path usually forgets about some vertices, but it really does feel like magic when you learn to do it properly.
(Also sorry if some of this explanation was confusing... I did my best without just making a whole tutorial video. Haha)

[A crosspost from cohost. The original was posted on Feb. 17, 2024.
Since I make vtubers as my main source of income, I figured more people might like to see this.]

[Also, whoops, I somehow accidentally put this post back in my drafts? Dunno how that happened. :T ]