What I take care of in creating the physics of the pupil. (Patreon)

*This article is a translation of an article I published on Pixiv Fanbox on June 10, 2023.

https://www.patreon.com/posts/cmo3-file-data-69537512?utm_medium=clipboard_copy&utm_source=copyLink&utm_campaign=postshare_creator&utm_content=join_link

Thanks to your support, the distributed data is very positive.

I'm always happy to see the originality of many people's Purupuru eyes.

The physics of puru-puru eyes is now so often seen in the Live2D community that it can almost be called a fad.

The expression of puru-puru eyes itself seems to have diversified, partly due to its compatibility with Vtuber models, which are often shown in bust-up mode.

In such a situation, there are probably some riggers who have the following problems.

'I have tried to make it in accordance with the trend, but it doesn't feel right to me.'

'I'm worried that I'm approaching it in the wrong way.'

The above problems have also been experienced by me in situations where I have created something other than puru-puru eyes.

For example, in order to create a model with a high range of motion, I implemented movements that exaggerated the movements of the human body so that the moving figure would look good, but it somehow didn't feel right in my mind.

I didn't know how to exaggerate the movements, and the basic movements themselves had a gestalt collapse.

As a result, the finished model is somehow awkward in its movements, and I find myself unable to judge whether I have created something honestly good.

The appeal of Live2D is that it can be moved in any way if you want to increase the movement as an expression.

That is why it is important to set your own personal standards for movement.

Oh, let me say here that, of course, it is great to incorporate eye physics as the best way to express what I think is the cutest and coolest.

I also respect those who are searching for ways to express those physics operations in order to maximize the 2D charm of Live2D.

This article was not written with the intention of criticizing them.

What would then be the solution to the problem of those who are now struggling with the physical representation of their eyes,

I think it is to think about why they came up with that expression.

In this article, I would like to explain the parts that I pay attention to in my production, after thinking about what the physics of the puru-puru eyes was created to express in my own way.

The basic structure of the parameters etc. is explained in this article. ↓

https://www.patreon.com/posts/live2d-structure-65791221?utm_medium=clipboard_copy&utm_source=copyLink&utm_campaign=postshare_creator&utm_content=join_link

First of all, the basic premise is that these eyes have "physically impossible movements".

This is true in the design aspects of the 'fish swimming' and 'bubbles',

The most striking aspect is that 'the eyes are stretching and contracting.'

Once you have this cmo3 file in your hands, you will understand,

↓, it incorporates a deformer that moves in a way that is impossible in reality.

By using physics to do this, the moment the eyes open and the moment the eyes close, there is a momentary movement of the eyes stretching and contracting, which creates a huge impact on the blinking."

This was explained in a previous article.

In other words, the blinking motion is exaggerated by adding physics to the eyes when they are open or closed.

As can be seen, the movement of stretching and blinking is in the same direction of movement.

And this movement is only triggered at the moment the same vertical movement of 'blinking' occurs.

In other words, I think it can be used as an expression like "daring to break the drawing to create impact" in animation.

I'm not an animator, so I could be wrong about a lot of things, but here's a diagram I tried to draw just to show you what it looks like. It is very similar to the way a ball is squashed and stretched when it bounces like this.

Draw attention to the eyes by exaggerating the blink.

By matching the direction of blinking and movement, blurring is created, like a mid-split in an animation, to create an optical illusion in a viewer's eyes.

I believe that the expression created with these intentions in mind is the physics of the Puru Puru eyes.

(At least, that is the intention with which I included the eye physics.)

Now, from this point on, I would like to explain what I pay attention to in my production process when adding eye physics.

(This is just a part of what I pay attention to, so this is not an absolute rule!)

・Ensure that the output is not too large.

Here are the current physics values and shaking levels.

As you can see from the actual data, the maximum output value for eye-related shaking does not exceed 100% even when the eye parameters are moved as much as possible.

The Shaking influence is also a little less than that of hair shaking to prevent excessive movement.

Looking at the inputs, the eye parameter, which is prone to large movements, has its influence reduced to around 20% to prevent the pendulum from moving in an unintended way.

Why would I care about the output and adjust it conservatively, though?

What would happen if we strengthened the values of both the input degree of influence, the Shaking influence and the output setting by about the default value?

The results will look like this.

Look at the output settings in the ↑ video.

With the default values, the maximum output swings out to a very large value of 300%.

Also, for the input, if the influence is too large, the pendulum movement is buggy and difficult to control.

*The red box above the video is the effectiveness.

The fact that the values are close to the defaults and that the shaking is large,

If you add this kind of physics without some understanding of its characteristics,

This means that the eye shaking will increase unintentionally.

Especially for beginners, even if you want to adjust it because it doesn't feel right,

It is difficult to know what is wrong and where to look.

I think there are many cases where you fall into such a situation.

So, even if you are thinking of implementing eye physics or have already done so.

"Are the base values too strong?"

"Are the outputs too far off?"

I would like you to check these by all means.

Also, the way I move the deformers,

I only move the 'upper half of the eye' during this movement.

I am careful not to move the entire lower lashes as well.

And it is this move that I wanted to tell you about in particular in this article. ↓

I regret very much that when I distributed the eye physics file before, I didn't explain at all what this movement is "for".

This is strictly a 'swinging the edge of the eyelashes' movement.

Blendshapes were not yet available at that time.

This was a good way to swing the main upper eyelash part, which already had movement connected to the opening and closing of the eyes.

However, when I distributed it, I forgot to explain the intention behind it,

As a result, I think some people thought it was a movement to rock the two edges of the eye.

In my file, the deformation looks like this ↓

If it is moved as a ↓ 'swinging movement of the two ends of the eye', it will look like this.

↓ Let's try to run it with physics.

Nowadays, you can use blendshapes to make them move nicely without having to go to the trouble of using a deformer.

Can you see the difference?

I think it will look quite different.

If you think it's difficult to get the right balance when you look at this, you don't need to include this 'swinging movement at the edge of the eyelashes'.

Even without it, you can create beautiful eyes.

It is good to move the art mesh directly like this.

・Reduce the width of the movement.

The only width to be moved is the edge of the lash.

If you are using a deformer, it is best to select a range with the Selection Tool and move only that area by using the Temporary Transform Tool, for example.

Be careful, because if you move it somehow, the eyes will move together, as in the video above.

I personally think that the inner canthus is a particularly difficult part.

I am conscious of really minute movements and adjust them less than the corners of the eyes.

In some cases, it may be fine without it.

After a lot of adjustments, when I try to make it without the movement of the inner canthus, it looks more beautiful that way…

Especially with this kind of eye design ↓.

This is a type of eye with a clearly drawn inner canthus.

Be aware that when moving the inner canthus with this, it is easy to feel uncomfortable with the exaggerated movement compared to other designs!

Finally, I would like to mention again the direction of eye stretching and shrinking.

With my process, the direction in which the eyes stretch and shrink is vertical, as shown in the video below.

Some of you may think that if they want to give an impact to the blink, it would look better if they move in the horizontal direction as well.

In fact, since Puru-Puru eyes became trendy, some models have been adding a horizontal stretching and shrinking movement like this to make the whole eye look soft and full.

Why do I include eyes stretching and shrinking only in the vertical direction?

The reason can be seen in this image I have just shown you.

The base blink movement is an up and down vertical movement.

The purpose is to exaggerate the blink by adding eye physics to create an illusion in the viewer's eyes, and to use the movements, which would be uncomfortable on their own, as an expression that "dares to break the drawing to create impact" in the middle of the animation, so the horizontal movements are not included.

When adding this two-stage eye movement, vertical and horizontal eye expansion and contraction, I think it is common to use physics to create multi-stage swaying.

However, if the shaking is in two stages, the movement of the second stage is conveyed as an expression of the eyes shaking, which is far from the main reason I included the eye physics.

But it's just for my purposes, so I may also add some horizontal movement to express the moist eyes, right? (For example, crying eyes, or a slime-type child...)

If you use this as a reference and are thinking about adding or adjusting eye physics in the future, choose the method that best suits your purpose.

Also, this is a digression, but in the previous illustration of the animation split-seconds method,

I said that only vertical stretching and shrinking is used, but by adding horizontal movement between the stretching and shrinking, for example, I think it is possible to create the optical illusion of exaggerated blinking, which is the objective, rather than eye swaying.

In that case,

try to eliminate the multi-stage swing and move them both at the same time and make them both one stage of the pendulum in order to keep the timing the same. (red frame)

I feel the swing is a bit too strong, so I'll suppress it.

There is no need to use two parameters, so I combine them into one.

So, to summarise the process so far, it's not a horizontal stretching and shrinking, but a contraction of the whole pupil.

Next, I took the bold step of erasing the vertical stretching and shrinking because it didn't feel right to swing it in two steps.

Here is the result of erasing it and making some adjustments.

This also looks good.

It's a stronger exaggeration than the vertical stretching and shrinking I usually use, but I think it looks charming.

As for the process,

・The pupil eliminates the multi-stage swaying.

・either vertically, horizontally or contracted.

This is a little different from the method I usually use, but I hope it will be helpful.

ーーーーーーーーーーーーーーーーー

The ideas discussed in this article on creating deformed movements can be applied not only to eyes, but also to many other situations.

・Why do I need to adopt this movement?

・To what extent should I adopt this movement to match the worldview of my model?

・If it doesn't feel right, what caused the discomfort?

It's okay if you can't think that well at first.

The road to improvement starts with imitation.

But the physics of the eyes is like a sporting analogy: a technique that is super high-scoring if it is done well, but has a low success rate and can cause serious injury if it fails.

Because it is a technique that looks good, you also have to think about whether it will match up right when combined with your own models.

I also think that an objective viewpoint is necessary to improve the quality in the future.

As you continue to work in Live2D, if you hit a wall, once you do, how does this movement look to anyone but you? Does it have the effect on the people around you that you think it does? It is also important to try to see things from other viewpoints than your own.

Although I have written about a lot of disadvantages this time, there are of course many attractive aspects to pupil physics.

For example, it doesn't matter if there is a universe inside the pupil, a flying dragon, a blazing fire or a fairy living inside the pupil.

The inside of the pupil is not limited to Live2D, but you see deformed expressions in various creative works such as manga and anime.

As a part of the world view and design, I think it is a place that can be freely accepted to a certain extent, so please try to show your originality.

I hope this will improve the quality of your eyes.

I plan to update various techniques in the future, so please do keep checking back!

(I think there will be more articles on hand tracking for a while!)

See you soon!