【Live2D Small Tip】 We think of the XY deformation of the back of the hair. (Patreon)

This will be a series of posts since my last status report article.

I apologize for only talking about myself, so I would like to quickly introduce one Live2D tip that I have found in my recent production!

As the title of the article suggests, the theme of this issue is “back hair”.

Among the back hair, I will talk about the “inner part”.

This is the part circled in the image below. (My model has a different inner color, so it is easy to understand.)

As those of you who have created Live2D models may sympathize with me, the XY deformation of this part is rather unexpectedly difficult!

I remember that I struggled a lot when I created my new model.

(The link below is an article I wrote at that time)

https://www.patreon.com/posts/progress-of-5-im-67071014?utm_medium=clipboard_copy&utm_source=copyLink&utm_campaign=postshare_creator&utm_content=join_link

When creating this part, it is normal to deform the deformer roundly “in the opposite direction” to the movement of the face. Probably most of the TIPS in the world, including course articles I have written in the past, explain it that way

However, with this method alone, the hair behind the ears and the hair behind the chin sometimes looked a bit skimpy, as if it did not have enough three-dimensionality.

(This is the area circled in red in the image below.)

I have done a lot of struggling on my model, such as adding a bunch of hair in the back, inserting an inner color in the side hair, and other things to get rid of the slightly skimpy looks.

I'll skip that part of the explanation this time, as it in detaile in the past articles I've pasted above.

So, what would it look like without the “struggling”?

It looks like this.

Do you understand? Why I wrote"looked a bit skimpy" 

(although,It's a very fine and minute difference. ......)

This is what it looks like after the adjustment.

Please compare with the video above.

Can you see the difference in the areas behind the ears and the back of the neck!

It still looks better because my model's hair style is a bob, but when I make long hair, this skimpy look tends to appear more pronounced. I don't know how many times I have been bothered by it in the past!

And I've never been able to verbalize why it feels so different, but recently I finally got an answer that makes sense to me.

I think the inner part of the back hair is made to cover the entire head like this,

but in reality, the inner part of the back hair that is visible when you are facing forward grows “from the nape of the neck”, so the hairline is here.

(If you touch the same part of your own back hair, you will see that it grows from the nape of your neck!)

The back hair that covers the entire head is actually located here. (② in the image below)

The part of the hair that is visible from the front, as explained earlier, is (①).

There is also hair between ① and ② (→③)

and as you've seen, actually the inner part of the back hair has thickness as well, and each has a different hairline!

Because this thickness of ① and ③ does not exist, and only ② is moved,I think this is why the inner part of the back of the hair is looking a little skimpy!

This is my hypothesis.

If you look at this video again with that in mind, don't you think it looks “ a little skimpy"?

If your Live2D model has relatively short hair, as mine does, you can fill this space by “adding a bunch of hair” as I lightly mentioned earlier.

But with long hair, it is difficult to use this technique.

The inner part of long hair is usually made of one part, and because all the hair is long, I think it is difficult to create a new hair bundle.

So, the technique I have been using recently for rigging long hair is to move the inner part of long hair as if it were growing from the nape of the neck in the first place.

I would like to explain the technique in detail, but I don't have a model with long hair at hand that I can show you by right, so I forced my model's hair to grow longer with deformers lol.

*I erased the body because it interfered with the hair.

*I also added a shadow for the inner part of the back hair. The original was a solid color + gradation, but having the shadows makes it more difficult to create a more three-dimensional deformation.

(Semi-Long Himono-chan, isn't this a nice look?)

Now, at a quick glance, the movement is beautiful, but when the model looks up wide, the space behind the ears and neck still bothers me.

some may not mind,but let's leave it this time.

And here it is after the adjustment.

It doesn't look different at all at a glance. ...... My model has too much hair to be a sample at all, I'm in trouble.

Let's zoom in more.

Before adjustment　↓

After  adjustment　↓

We can manage to see the difference.

Can you see that the space just behind the neck is narrower after the adjustment?

If you just look at the inner part of the back hair, you can see the difference more clearly.

See also the movement of the deformer for reference.

(Don't worry that the layer order of the ears is buggy, because we can't usually see them...)

Before adjustment　↓

After  adjustment　↓

By daring to shrink the inner part forward and increase the  density of the hair, we can make the movement that this hair grow just behind the neck, from the nape of the neck.

I think few people actually move it to the 90 degree sideway, so I'll also put up some angles that might be easier to reference. The range of motion of the above picture is about this much deformation.

The movement of the inner part on the Y axis also dares to make the back of the neck follow the neck, and by making the movement width smaller than the other hair parts, I think it can give the impression that it is growing out of the neck.

When we use this deformation method, we will lose hair here (circled in red in the image above),

so it is necessary to have hair on the front to cover the loss,

If your model has hair on the front part, I think this is a very useful method! Of course it depends on the hairstyle of your model!

My hair is such that my ears are not visible when I turn my head to the side, but VTuber models often have visible ears, so I made a version of that for testing.

Before adjustment　↓

After adjustment　↓

Yeah, but I still can't tell much of a difference! Too much hair!

But when it comes to making other VTubers' bodies, I don't think there are many that are prepared with the side part of the back of the hair as dense as this my hair.

(↑My back hair side has so many parts)

In this case, unless we prepare some additional parts, I think the basic rigging will be done with some inner parts visible, and that's when I think the technique will come in handy.

Well, maybe, maybe?

Anyway, that's all for this issue. 

I hope this article was of some help to you all. ......

I'm going to keep writing little articles like this, so I'll keep posting updates without any pressure.

See you later, Alligator.