【High-Quality Live2D Tutorial for Beginners】 Eye Physics ④ Rigging Eyebrows and Creating Eyeball Depth (Patreon)

Hello everyone, this is Himono.

Let's continue with the beginner tutorial this time too!!

Previous article is here

https://www.patreon.com/posts/146985988

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<Table of Contents>

[Optional] Creating physics calculations for →Iris Highlight

[Optional] Creating physics calculations for →Iris Reflection

[Required] Creating eyebrow movement

[Required] Creating eyeball XY movement

[Optional] Creating eyeball XY depth

※You can easily jump to the relevant section by inputting the table of contents above with Ctrl+F (or command+F)

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[Optional] Creating physics calculations for →Iris Highlight

Duplicate the →Eyelash physics calculation group we made at the end of the previous article, and this time create physics calculations for →Iris Highlight. Change the settings as follows!

Input Settings

Whether to invert or not is fine either way. Choose based on preference! For the Position X part of Normalization of input, the distributed file has ±30 but ±10 seems better, so I've changed it to ±10 in the article.The reason is in the physics model settings section.

Physics Model Settings

We're changing the values drastically. By reducing the Duration, increasing Shaking influence, and slightly decreasing Reaction time, it becomes a rapid, intense movement.We want the iris highlight to move in short, rapid movements like sparkle sparkle sparkle! glitter glitter glitter! so we do this.

If you set the Position X value in Normalization of input to ±30 like earlier, the pendulum gets thrown around too much by intense blinking movements and the movement bugs out like this↓. When including intense movements like blinking in input settings, the pendulum tends to bug out easily, so it's recommended to set Normalization of input and Effectiveness to smaller values to prevent pendulum bugs, and adjust the ease of movement with the Scale in output settings.

Output Settings

Put ★→Iris Highlight 1 in stage 1, and ★→Iris Highlight 2 in stage 2.

The magnification has become an extremely subtle value, right? This was set by pressing the two buttons on the right side called "Increase Output" and "Decrease Output ."

After finishing the three settings—Input Settings, Physics Model Settings, and Output Settings—when you randomly move the 〇Left Eye Open/Close parameter, or turn ON "Automatic eye-blinking" from Preview in the top left menu to move it automatically (see previous article for details), the "Output Maximum" value fluctuates like this.

↓When moving randomly

↓When moving automatically

If this Output Maximum exceeds 100, it means the movement "exceeds 100%, meaning it's too large and goes beyond the limit." So by pressing "Decrease Output," it automatically changes to a magnification that fits exactly to 100%.

Conversely, if the Output Maximum doesn't reach 100, it means the movement is "not being utilized to its maximum." You can also press "Increase Output" to automatically change it to a magnification that fits exactly to 100%.

In my tutorials and distributed files, when magnifications(Scale) have subtle decimal values, I'm usually using these output adjustment buttons.

Whether you use automatic eye-blinking or move it yourself, the calculation results change slightly each time, so the Output Maximum and corresponding magnification also change slightly each time. So don't trust the calculation results too much—try adjusting once, and if you don't like the movement, press the adjustment button again, or manually adjust based on that value... that kind of approach is good. Your calculation results will probably differ from mine too. If you want to make exactly the same movement as the distributed file! you can copy and paste the values from the distributed file!

Though it doesn't appear in this article, due to this specification where "calculation results change slightly," for movements like "→Iris Highlight" and "←Iris Highlight" where "the same movement range on left and right looks better," after setting the magnification on one side, copy and paste that value to create the other side's movement.

The finished version looks like this! The highlights are so sparkly and very cute! The pupils suddenly became brilliant!

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[Optional] Creating physics calculations for →Iris Reflection

Continuing, let's create the iris reflection light movement. What even is reflection light movement, but at this point it's almost fantasy, so please incorporate it if you think it's cute! Don't think about the details!

Duplicate the "→Iris Highlight" we just made.

Input Settings

Here the Position X value in Input Normalization is set to ±30. As I'll show right below, the reflection light has leisurely pendulum movement so it moves beautifully even with this!

Physics Model Settings

Increase Duration, decrease Shaking influence, and make it a leisurely movement.If I were to forcibly explain the reflection light movement in terms of real-world movement, it would be like: the mucous membrane and moisture covering the cornea flow with blinking, and this flow changes how light hits.Since the moisture covering the cornea has viscosity compared to normal water, making the movement a bit more leisurely increases persuasiveness, or so I personally think.

Output Settings

Put ★→Iris Reflection 1 in stage 1, and ★→Iris Reflection 2 in stage 2. The scale was adjusted by pressing the output adjustment button as before.

For Output Maximum, unless it's something requiring precise movement like angle correction, if it's within 90-120%, I think there won't be much sense of incongruity even if it's not 100.If there's no sense of incongruity, it's OK even if the values protrude a bit. If it becomes like 50 or 150, unless it's intentional, you might want to adjust it!

The finished version looks like this. The sparkly feeling increased even more. So cute!!

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[Required] Creating eyebrow movement

Close the physics calculation settings temporarily and create eyebrows here. We haven't explained mesh division and such for a while—do you all remember how to do it? Let's try it as a review!

The eyebrows have a slightly special structure—they sandwich the bangs parts with a normal eyebrow part and a line-art-only eyebrow part.

Without this line-art-only eyebrow part, the eyebrows are barely visible. But bringing the eyebrows to the front creates a sense of incongruity.

A common solution is: copy-paste the eyebrows and lower the opacity → place them on top of the bangs. This alone makes them blend quite well.

This time we went one step further and made the part layered on top into a new part called "line-art-only eyebrows."By doing this, we can assert the eyebrows without hiding the delicate paint variations of the bangs. The line-art-only eyebrows and normal eyebrows move simultaneously.

Now that I've explained the principle, let's divide the mesh!It's very easy to select both the line-art-only eyebrow part and normal eyebrow part while holding Ctrl.

I made a mesh that sandwiches the inside and outside of the line art.

If you don't remember how to divide meshes, read this article!

https://www.patreon.com/posts/126322022

Once you've divided the mesh, create a deformer with multiple parts still selected. Name it "Eyebrow → Curve," with a Warp division of 9×5.Also enlarge the size a bit with Ctrl+Shift+Alt+Drag.

Usually eyelashes are often moved by directly moving the art mesh, but this time since there are two eyebrow parts per side, and it's easy to move with a deformer because they're round eyebrows, we'll use a deformer.

Select the deformer and place keys on the four parameters already created above.

Then deform as follows:

〇Eyebrow Up/Down

As the name suggests, it's a parameter that moves the eyebrow position up and down, but we move it slightly differently for the upper and lower sides.For the upper side, just slide it up while holding the Shift key, but for the lower side, narrow the vertical width a bit. Make sure the distance between the deformer's bottom line and the double eyelid doesn't get too close!

If that distance is too close, there's a risk the eyebrows will penetrate the double eyelid when you move angle and deformation parameters together later.If penetration happens later, fine-tune the position.

★Left Eyebrow Angle

It's a bit difficult, but use the deform brush and such to deform it so it draws a curve up and down.

As you can see in the video, this parameter also moves the eyelashes a bit. Create a new deformer to use. The objects to include are as follows:

Small Eyelash →Large Eyelash → Outer Corner Eyelash → Lower Eyelash →Tear Bag → Sclera Shadow → Sclera → Double Eyelid → Highlight Flower → Eye Blink Highlight Lower → Eye Blink

To put it more simply, among the objects in the "Eye → Curve" deformer we made in the article↓,it's everything except "Iris → Eye Blink."

https://www.patreon.com/posts/141862856

When selecting multiple items during deformer creation, I think it's easier to do it from the deformer palette below rather than the parts palette. As you can see, since we've already made the "Eye → Curve" deformer, the deformer palette displays what's inside that deformer in an organized way.You can select multiple items at once with the Shift key without having to select them bit by bit with the Ctrl key, so it's easy.

↓Deformer Palette

↓Parts Palette

In this state, let's create a new deformer!

Name it "Eyelash →Curve" with a Warp division of 12×12.

Please refer to the image for the deformer size.We'll enlarge it a bit, but maintain a good size difference from the parent deformer "Eye → Curve."

If you've selected the objects correctly, when you move the Eyelash → Curve deformer, only the iris gets left behind like this!

Once the deformer is created, place a key on the ★Left Eyebrow Angle → parameter and deform as follows.The image is that the eyelid skin is being pulled along with the eyebrow movement.

Like this, it's super easy—you just need to move the green frame (Bézier) while holding the Shift key to match the eyebrow's movement range.

★Right Eyebrow Angle

Since we want the eyebrows to move asymmetrically, we'll also use the right side parameter even though it's the left eyebrow. Move only the inner eyebrow like this.

I use the deform brush for everything. Like this, use the edge of the brush to gradually deform it.

〇Eyebrow Deform

Super easy. Only at -1.0, rotate it slightly to make angry eyebrow. You don't need to angle it too much.

Once you've deformed up to here, set 〇Eyebrow Up/Down, ★Left Eyebrow Angle, ★Right Eyebrow Angle, and 〇Eyebrow Deform all to -1.0 and check if they penetrate the double eyelid! If they penetrate, fine-tune the position of 〇Eyebrow Up/Down.

Angry Nyanchan is cute!

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[Required] Creating eyeball XY movement

Let's continue deforming. This time we'll create the movement to move the eyeballs around (eyeball XY)!

Use the existing "iris → Eye Blink" deformer and "〇Eye Ball X" and "〇Eye Ball Y" parameters. Don't forget to make 〇Eye Ball X and 〇Eye Ball Y into blend shapes!

This is the left/right iris movement. Rather than just sliding left and right, we're adding a bit of perspective (depth).

※Your screen probably doesn't have this black line that appears at the white eye boundary when moving the eyes around. I'll explain this later, so ignore it for now.

This time we'll use the green frame (Bézier) instead of the deform brush to move it. At this time, if you set the Bézier type to "Level 3," it applies rounded deformation correction instead of angular movement.Recommended when moving spherical objects like pupils.

Default(Retain Control structure)

Level3

As for how to move it, first slide it left and right normally, then move the Bézier to narrow the width on the far side. Furthermore, move the center also slightly toward the far side to add roundness.

※ Patreon has a limit of 25 embedded videos... so from here on, videos will be GIFs instead. Sorry!

https://drive.google.com/file/d/1CM7jr9AAQnmdUSUp-4FCkIDjvSh0cAxu/view?usp=sharing

I casually do this in the video, but by default the center part of Bézier becomes overall movement, so press the × button at the bottom right of the deformer before moving it. (I feel like I said this in a previous article but I forget when I said it, so this is a reminder)

Use "Motion Mirroring" for the opposite side (-1.0) movement. I also forget if I said this in a previous article, but this is a different method from the "Blend Forms" we talked about before for creating opposite-side movements.

With 〇Eye Ball X at 1.0 (the value of the movement we just made), select "Motion Mirroring" from the three-line mark at the top right of the parameter palette.

Then a screen like this appears. Confirm that "Flip horizontally" is checked and press OK.

When you press OK, the -1.0 key of 〇Eye Ball X glows red. This is the signal that reversal succeeded.

As you can see, the reversal is done! However, with the same movement range, -1.0 is a bit too cross-eyed, so I slide it while holding the Shift key to move the position slightly toward the center.

https://drive.google.com/file/d/1l-sn-0fdyWGPCkxb7lokQBm_0vOE5CbX/view?usp=sharing

By the way, "Blend Forms" reversal can't be used for this movement! If you try using it, this happens:

https://drive.google.com/file/d/11B82JuKN43jrVu4fd-ek8wLUWWCXIgcu/view?usp=sharing

Can you see something is off? Even though we want to add perspective by "narrowing the far side," this creates a movement where "the near side expands." Blend Forms only "moves vertices in the opposite direction," so what was narrowed moves in the opposite direction and expands. There's no concept like left-right symmetry there.

Like this, Blend Forms and Motion Mirroring have different uses depending on the type of movement. After using them for a while you'll get a feel for when to use them, but if you don't know, it's also valid to try both and adopt whichever moves cleanly and remember the situation. ※There are also quite a few patterns where neither works lol

〇Eye Ball Y

The way to move it is exactly the same as before! The horizontal movement just became vertical! As a note, this time when using Reverse Motion, change the check to "Flip vertically."

https://drive.google.com/file/d/1DFoRCOeMFTcG5UOpgw2A_qeZRit8zv-f/view?usp=sharing

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[Optional] Creating eyeball XY depth

The movement we just made is already beautiful enough, but we'll devise various ways to bring out more depth in the pupils. I made this an optional section.

First, let's indent the pupil.

What the heck does "pupil indent" mean... but this is a super popular expression used extensively not only in Live2D but throughout the illustration and anime industry.

Looking at this illustration we used in the past in this tutorial, you can see that the cornea (the membrane covering the black eye part) bulges compared to the eyeball. Conversely, the pupil part (crystalline lens) is flat. ※In my past tutorials I've expressed that the crystalline lens part is indented, but in terms of human body structure, it's more correct to say it's flat rather than indented, so I'll express it that way from now on. If anything, it's more like the cornea bulges!

So, when we made the eyeball movement earlier, I believe we rounded the center of the deformer toward the far side. This is precisely the deformation that expresses the cornea's bulge.

However, since we moved everything at once with the deformer, this bulge is also reflected in the pupil part. We want to show that "the pupil part is flat." That's the end of the principle explanation! Let's move it.

Select the Iris → art mesh and place keys on 〇Eye Ball X and 〇Eye Ball Y, Just like when we made the pupil sway, select only the pupil part with the lasso tool, and slide it just slightly toward the center while holding the Shift key.

https://drive.google.com/file/d/1iRaIB38-FhARxnHXoY0wwsPaDrBaXf2b/view?usp=sharing

Continuing, let's emphasize the "cornea bulge" a bit more too! Select both Add 50% Iris Reflection → and Add 60% Iris Highlight 1 →, place a key on 〇Eye Ball X, and bulge it toward the far side with the deform brush.

https://drive.google.com/file/d/1utNzfUR33bQpxOOEr-zFRQylE8tSN7uc/view?usp=sharing

I'd like to say do the same for 〇Eye Ball Y too... but Eye Ball Y gets a completely different movement.

That's this. It's really hard to explain... but if I had to say, it's like a movement where "the pupil slides but the light stays in place."

https://drive.google.com/file/d/1chug2PPZOW60t2WOQaWPjOuXqya8o_rf/view?usp=sharing

As real-world highlight and reflection light movement, Eye Ball Y is more correct.Unless the light source position changes, the highlight position doesn't change even if you move the eyeball.

However, if we do this for 〇Eye Ball X too, the cornea's bulging feeling decreases, and after various trial and error, I settled on something like "X-axis movement prioritizes bulge" and "Y-axis movement prioritizes light source."Please use whichever you prefer! Both are widely adopted as Live2D expression methods!

We'll also move the eyelashes just a tiny bit. The image is that the eyeball skin is being pulled slightly by the eyeball movement. Use the "Eyelash → Curve" deformer we made when doing eyebrows. At this point I think you can make it without detailed explanation. Try making it while looking at the videos and distributed files!

https://drive.google.com/file/d/1fZvQ0QEs-1IcIb8bXsm8V5ooadwK_oxw/view?usp=sharing

That's all for this time! What we talked about today wasn't that complex in terms of how to move things, but I think there are very few beginners who properly understand the principles and can create pupils elaborately up to this point. So you beginners who read this have super leveled up! I hope!!

Look forward to next time! See you!!