🧭 Lesson Objective

1️⃣ Learn how to make physics parameters

2️⃣ Learn how to access the Physics window and understand how physics works

3️⃣ Learn how to add physics to the eyelash

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🎯 Lesson Quests

🚩 Quest 1: Create Physics parameters for the Eyelash
🚩 Quest 2: Learn How Physics Works
🚩 Quest 3: How to Add Physics to the Eyelash

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🚩 Quest 1: Create Physics Parameters for the Eyelash

We’ll need to create two Blend Shape parameters that will control the eyelash’s physics motion:

• EyelashL 1
  • Blend Shape = ✅
  • Min: -1 | Default: 0 | Max: 1
• EyelashL 2
  • Blend Shape = ✅
  • Min: -1 | Default: 0 | Max: 1

These parameters will act as outputs for the physics motion.

🛠️ Recommended Tool: Temporary Path Deformation

Instead of using the deform brush tool, try using Temporary Path Deformation for smooth deformer bending.

1. Go to File > Keyboard Shortcuts
2. In the search bar, type "Temporary Path Deformation"
3. Set a shortcut (e.g. CTRL + B)

Now when a parameter is set to a key value, press your shortcut to activate the Temporary Path Deformation Tool.
You can then:

• Click points to create a line
• Drag the line’s points to deform your mesh cleanly and smoothly

This tool behaves similarly to the Deform Path Edit Tool, but gives better control for soft rigging effects.

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🚩 Quest 2: Learn How Physics Works

Physics in Live2D uses the concept of a pendulum system:

• Input Parameter → moves the pendulum
• Pendulum Motion → settings determines the motion
• Output Parameter

👁️ For our eyelash setup:

• Input Parameters → EyeL Open, EyeL Smile
• Output Parameters → EyelashL 1, EyelashL 2

As the eye opens and closes, the input parameters move the pendulum, which go through the pendulum and apply the movements to the output parameters.
This gives your eyelash subtle bounces and squishy effects — especially during quick blinks or movement.

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🚩 Quest 3: How to Add Physics to the Eyelash

🔧 Step 1 – Open Physics Settings

Go to Modeling > Physics Settings...
A new physics editor window will appear.

🔧 Step 2 – Add a New Physics Group

1. Click “Add…” in the top-left
2. Name it: Eyelash Physics Left
3. Press OK

🔧 Step 3 – Add Input Parameters

1. In the left panel, click the Input tab
2. Click “Add…”
3. Select both EyeL Open and EyeL Smile as inputs

🔧 Step 4 – Add a Pendulum

1. In the Pendulum Settings area below, click the dropdown
2. Choose: Hair (Double Pendulum)
3. Press Import

This gives you two pendulum points.

In this case, becuase we have two output parameters, the two different pendulums will be keyed to separate blend shapes, adding to the overall bounce effect.

🔧 Step 5 – Add Output Parameters

1. Switch to the Output tab
2. Click “Add…”
3. Select: EyelashL 1 and EyelashL 2
4. You’ll see each output attached to a specific pendulum point

You can also check the "Reflect" boxes to flip the motion if it looks better inverted.

🔍 How to Preview

Use the parameter sliders in the center of the window to preview the input motion.

You can also simulate auto-blinking for better testing:

1. Go to Modeling > Parameter > Settings for Eye Blinking & Lip-Sync...
2. Check off EyeL Open and EyeR Open
3. Press OK
4. In the physics window, go to Preview > Automatic Eye-Blinking to toggle it on or off

🔧 Physics Input Types: Position X vs Angle

There are two ways the input parameter can drive the pendulum:

Position X

• The output will always return to its default value

Angle

• The output stays at a new value, depending on how the pendulum was affected

Choose based on whether you want “bouncy back” motion or longer drift/momentum.

⚙️ Pendulum Settings – What They Do

The settings of the pendulum change how the physics will look.

In general, this is a description for what each setting does.

Duration:

• How long or short the pendulum is.
• Will make the physics seem heavy or light.

The higher the value, the "heavier" the physics
The lower the value, the "lighter" the physics

Shaking Influence:

• How much the pendulum shakes after an input is made

The higher the value (max of 1) the more the pendulum will shake
The lower the value (low of 0) the pendulum will not shake at all

Reaction Time:

• How fast the pendulum will move to copy the input movement

The higher the value, the faster the reaction
The lower the value, the slower the reaction

Overall Acceleration:

• How fast the output will accelerate to it's resting value

The higher the value, the faster it will finish its movement
The lower the value, the longer it will take to finish its movement

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🧪 Best approach: Play with these settings and see how they visually affect the lash bounce!

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📦 Study File

Level 2 - Stage 2 | Study File

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🏁 End of Level 2 - Stage 2 | How to Add Physics (To the Eyelash)