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How Nana prepares their model for Live2D (Part 6)

Updated: Nov 30, 2021

Continuing from where we left off last time we are going to have a first look into the physics in Live2D today and also talk more about warp deformers for a bit and try to turn the face to the sides.

Let's go through what the plan is here
  • We are going to make use to what we've already learned and add some physics to our model's hair.

  • We are going to assign parts of the face to warp parameters and group them so that they are interconnected.

  • We are going to explore the Angle X and Angle Y parameters.

  • We are going to learn about mirroring (aka reflecting) positions of a warp deformer.

Without further ado, let's get started.

Adding Physics to the Hair

One of the things which make a model more lifelike in a jiffy is the physics built into Live2D. For our blog series, I am going to show that in form of the hair and the hair bow of our sample character.

Every new Live2D project already has 3 parameters prepared for it, but be aware that you can create new physics parameters at any time. But for our purposes, we are going to use what we already have here. This setup basically assumes that you have three hair groups as the names of these parameters suggest. To keep things easy, we will do this just the way it was intended to. Let's first start with the front hair.

Select the front bangs of your hair and assign it to the Hair Move Front parameter with 3 points. I am going to use the deform path tool for moving the hair and I will add multiple ones to the same part. Now usually the program only expects you to use 1 but there's a workaround for this (you could also split the front hair into multiple parts before importing the .psd file if you want to, but I've wanted to save up on layers).

Start with the first deform path. After that, leave the deform path edit tool, deselect the front hair part. Then, select it again and go back to the deform path edit tool. This allows you to draw a new path. Do this as many times as you want, the result will look something like this:

Similar to before, we will now move the parameter to the farthest out positions and start animating the hair.

You will notice that the paths will interact with one another and you will have to do this by trial and error.

But thanks to the multiple paths, it should be fairly easier than without any or only 1 path.

Let me show you the 3 positions for the front hair, I might clean this up a bit after this blog entry, but the general idea is here:

Once we have that set up, we can finally go over to the physics window. To open that window, go to "Modeling" in the top navigation and select the bottom option "Open Physics/Scene Blending Settings".

The first thing which will probably catch your eye is that the model is displayed here and that there are buttons to run a simulation such as the start and stop button. Feel free to play with it to look at your current work in progress, but we are currently not here for that. So once you had your fun, please continue with the read :).

First, click on the add button, this will open a new pop-up window. Here, you will be able to create a new physics group.

Give it a name you'll be able to recognize later (something like FrontHairPhysics for example). Then, decide on the input preset (in this case the head) and a physics model preset. Experiment with the physic presets, each of them behave differently and you can still change them afterwards. For now, just select one and click on 'ok' (FYI, I am using the short hair one due to how my model's front hair looks like).

You will notice, that while you have now created a physics group, it doesn't do anything... that's because you haven't defined the output for this group yet.

To set up the output, first click on the output settings and then the "Add" button, both were previously been greyed out.

Select the parameters which you want to have this physics group interacting with. In this case, the Hair Move Front group, then click on 'ok'.

Now look and behold, if you fool around with the model on the right, you should be able to notice, that it now has physics applied to it.

You can modify the physics settings on the left side of the physics/scene window, I won't go into the details too much here, it's best to try things out on your own. For starters, you can just try out the different presets, just select another one and click on import. You can see that each pendulum section has 5 different numbers assigned to them, you can change those numbers manually. Figure out what settings work best for you.

With that, I'll set up all the other hair parts and the hair bow, assigning them to the three different groups.

Here you can see the result of the physics on the hair and hair bow. Ideally make sure that the parameters are not set exactly the same.

If you do, the physics on the hair parts will be exactly the same and as a result, it will look the same, as if you had done them on the same parameter.

Experiment with the physics in Live2D, you may find many uses for it which you wouldn't have thought about doing before. Small physic effects can also make a model much more lively. It's a wonderful tool.

I will continue with the next topic I've wanted to have covered today.

Grouping parts and warp deformers

What I want to talk about next is how to make use of warp deformers to deform multiple parts. This is especially helpful for the turning of the face, as well as movement of the body later on. In order to properly learn what we are about to go through, you have to understand how the hierarchy in Live2D works. In other words, it's like putting small boxes into a bigger box, hence "boxing".

Taking the face as an example, we are looking for a warp deformer for the whole face, including eyes, nose and mouth. Instead of putting everything into 1 warp deformer, what we are going to do here is to put the eyes into separate smaller boxes first, and the same for the mouth.

Here's a rough overview of what we are going to do:

  • Face Deformer

    • Left Eye Deformer

      • Left Eye parts...

    • Right Eye Deformer

      • Right Eye parts...

    • Mouth Deformer

      • Mouth parts

    • Nose Deformer* (*I will skip this one for this model, because it doesn't have a drawn out nose)

      • Nose part

    • Face Base Deformer

      • Face part

The Face Deformer, once we are finished with it, will be packaged in a head deformer, along with will the hair parts. By the end of the project, each part should be assigned to another part and only one should be assigned to root.

We shall start with creating the deformers for both eyes. In order to do that, we have to select all parts, which are going to be part of the deformers. Careful, remember that I've already created a deformer for each iris previously, this means that we have to exclude the iris parts when selecting the parts, since those are already assigned to their respective deformers.

Our result will be a new deformer as planned, and the iris deformer will be already be assigned to this new deformer.

We shall repeat this step with the mouth and the other eye next. And once we are done with that, we will create a face deformer which has each other sub deformer and parts on the face without deformers assigned to.

Here's a screenshot of how this would roughly look like, I've selected them all and dragged them away from the rest of the model to confirm, that I have actually selected each deformer and the nose, which is not assigned to any deformers because the shape is too simple for me to deform.

As you can see, I've decided to have more divisions on this deformer, since I will be doing a lot of deforming on this one. We will mainly be working on this deformer for the face parameters. There is a possibility however, that we will also be moving and deforming the created sub warp deformers for when the face is looking to a side. For starters, let's just try to make the face turn to one side.

Here you can see the rough result of me turning the face, I've removed the hair so that it is easier for me to work on.

In order to make it look like that, I haven't only deformed the face deformer, but I've also made slight changes on the sub deformers assigned to it and I've also moved the nose and ears.

So... why did I mention that I'll be only be doing one side? Some of the readers may already know why I've phrased it that way and their guess is right. Since one of the updates of Live2D, there's been the option to reflect a parameter, mirroring the deformation in the process.

In order to do so, select all parts and deformers you want to mirror, click on the expand tab on the far right top corner of the parameter window and select 'Reflect Motion'. Important, you have to be on the correct key point in order to make this work. in this live example I was working on the position on the very left.

Now you will see that this will not always work (like in my case it didn't turn out great. In such a situation, you'll have to do it separately for each part and deformer. Also you can also do this manually and some parts you will have to correct manually. Don't worry too much if the left and right view is not exactly identical, our faces are also not perfectly symmetrical :).

Once the face is done, do the same with the hair and other objects on the head (in my case the hair bow and the penguin). Assign them to deformers and group them if necessary.

Here's the current result of left and right head turn, note that I've also already assigned the head deformer to a rotation deformer, I will talk about those soon.

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