ShapeSync

Chapter 6: Advanced Figure Registration and Partial Body Deformation (PBM)

← Back to Tutorial Index ｜ ← Chapter 5: Shape Registration and Shape Director Operation Check

This chapter explains the procedure for registering Partial Body Morph (PBM), which deforms only specific parts of the character (in this tutorial, chest BreastSize), and how to configure outfits (Dress) to follow partial body deformation of the base body.

First Half (VRoid Studio): Create Base and FBM .vroid data with modified chest sizes, and export 4 PBM VRMs in total for base body (Figure) and outfit-equipped model (Dress).
Second Half (Unity / ShapeSync): Register PBM (BreastSize) on the Figure side in ShapeSync Editor, configure PBM tracking on the Dress side, override and redefine the Morph Shape (morphSampleI), and verify synchronized operations using ShapeDirector.

1. Introduction (Concept of PBM: Partial Body Morph)

FBM (Full Body Morph): Overall body shape changes of the character (e.g. SampleI) covered in Chapters 2 to 4.
PBM (Partial Body Morph): Partial body deformations that independently deform specific parts of the character such as chest size, shoulder width, or leg length.
ShapeSync Core Feature: PBM is a basic mesh deformation feature built natively into ShapeSync Core (it is not a VRM facial expression feature or an external extension package feature).

2. Creating .vroid Data for BreastSize (VRoid Studio)

First, use VRoid Studio to create .vroid data with modified chest sizes for the Base body and FBM body.

2.1 Creating Base PBM Data

Launch VRoid Studio and open the base body model BasicFemale.vroid created in Chapter 2.
Select the Body tab in the top menu, and set the Chest Size slider in the parameter list to 1.000 (maximum).

Setting Chest Size to 1.0 on Base model ▲Figure 6-1: Opening BasicFemale, going to Body > Chest Size, and setting to 1.0

From the top left menu, select “Save As” and save the file with the name BreastSizeBasicFemale.vroid.

▲Figure 6-2: Saving as BreastSizeBasicFemale.vroid using Save As

2.2 Creating FBM PBM Data

Next, open the FBM base body model SampleI.vroid created in Chapter 2.
Select the Body tab, and similarly set the Chest Size slider to 1.000.

Setting Chest Size to 1.0 on FBM model ▲Figure 6-3: Opening SampleI, going to Body > Chest Size, and setting to 1.0

From the top left menu, select “Save As” and save the file with the name BreastSizeSampleI.vroid.

▲Figure 6-4: Saving as BreastSizeSampleI.vroid using Save As

3. Exporting PBM VRMs for Figure (VRoid Studio)

Export PBM VRMs for the base body (Figure) from the 2 created .vroid files.

3.1 Exporting BreastSizeBasicFemale.vrm

With BreastSizeBasicFemale.vroid open, select Export VRM from the export button in the top right.
Select VRM1.0 and open the export screen without configuring reduction settings.
Confirm that the polygon count (19214), material count (9), and bone count (59) match the Base body model.

Checking VRM export settings for BreastSizeBasicFemale ▲Figure 6-5: Checking polygon count, material count, bone count, and exporting as BreastSizeBasicFemale.vrm

Enter BreastSizeBasicFemale in Avatar Name, and export as BreastSizeBasicFemale.vrm into a folder within the Unity project.

3.2 Exporting BreastSizeSampleI.vrm

With BreastSizeSampleI.vroid open, similarly select Export VRM.
Select VRM1.0 and verify polygon count (19214), material count (9), and bone count (59).

Checking VRM export settings for BreastSizeSampleI ▲Figure 6-6: Checking polygon count, material count, bone count, and exporting as BreastSizeSampleI.vrm

Enter BreastSizeSampleI in Avatar Name, and export as BreastSizeSampleI.vrm into the Unity project.

4. Exporting PBM VRMs for Dress (VRoid Studio)

Next, export 2 PBM VRMs with the outfit (Dress) equipped.

4.1 Exporting Dress1BreastSizeBasicFemale.vrm

In VRoid Studio, open BreastSizeBasicFemale.vroid.
Select the Outfits tab and equip the preset dress (Dress) used in Chapter 4.

Equipping Dress on BreastSizeBasicFemale ▲Figure 6-7: Opening BreastSizeBasicFemale and equipping Dress

From the export button in the top right, open export with VRM1.0.
Verify polygon count (32368), material count (14), and bone count (159).

Checking VRM export for Dress1BreastSizeBasicFemale ▲Figure 6-8: Checking polygon count, material count, bone count, and exporting as Dress1BreastSizeBasicFemale.vrm

Enter Dress1BreastSizeBasicFemale in Avatar Name, and export as Dress1BreastSizeBasicFemale.vrm into the Unity project.

4.2 Exporting Dress1BreastSizeSampleI.vrm

In VRoid Studio, open BreastSizeSampleI.vroid.
Select the Outfits tab and similarly equip the preset dress (Dress).

Equipping Dress on BreastSizeSampleI ▲Figure 6-9: Opening BreastSizeSampleI and equipping Dress

From the export button in the top right, open export with VRM1.0.
Verify polygon count (32368), material count (14), and bone count (159).

Checking VRM export for Dress1BreastSizeSampleI ▲Figure 6-10: Checking polygon count, material count, bone count, and exporting as Dress1BreastSizeSampleI.vrm

Enter Dress1BreastSizeSampleI in Avatar Name, and export as Dress1BreastSizeSampleI.vrm into the Unity project.

5. Registering Figure PBM (BreastSize)

From here, the work is performed in the Unity Editor. First, register the PBM (BreastSize) on the Figure side.

From the top menu in Unity Editor, open Tools > zgock > ShapeSync > ShapeSync Editor.
Select Figure > PBMs from the left TreeView.
Click the Add PBM Entry button.
In the displayed “Register PBMs” section, enter BreastSize into PBM Name.
Figure axes are displayed in the PBM Prefabs list.
- In the BasicFemale row (Base body), drag and drop BreastSizeBasicFemale.vrm from the Project window.
- In the SampleI row (FBM axis), drag and drop BreastSizeSampleI.vrm from the Project window.
Click the Save to Database button at the very bottom of the screen to save (The Prefab on Database column on the right displays saved state and is not directly edited).

Registering PBM BreastSize to Figure and assigning VRMs ▲Figure 6-11: Entering BreastSize for PBM Name in Figure > PBMs, assigning Base / FBM VRMs, and saving

6. Registering PBM Tracking on Dress

After registering the Figure PBM, configure the outfit (Dress1) to follow that PBM.

[!IMPORTANT] Always register the Figure PBM first before configuring outfit tracking. The outfit side selects tracking relationships based on the PBM axes registered to the Figure.

From the left TreeView in ShapeSync Editor, select Outfits > Mesh Outfits > Dress1 > PBMs.
In the displayed “Mesh Outfit PBMs” list, check Follow BreastSize to enable it.
Once enabled, VRM assignment rows will appear.
- In the Base Prefab row, drag and drop Dress1BreastSizeBasicFemale.vrm from the Project window.
- In the SampleI Prefab row, drag and drop Dress1BreastSizeSampleI.vrm from the Project window.
Click the Save to Database button at the very bottom of the screen to save.

Configuring PBM tracking on Dress1 and assigning VRMs ▲Figure 6-12: Enabling Follow BreastSize in Outfits > Mesh Outfits > Dress1 > PBMs, assigning Base / FBM VRMs, and saving

7. Overriding and Redefining Morph Shape (morphSampleI)

Add deformation weights for the newly added PBM (BreastSize) to the Morph Shape (morphSampleI) created in Chapter 5, and overwrite-save it.

From the left TreeView in ShapeSync Editor, select Shapes > Morph Shapes > morphSampleI (Do not create a new Shape Id).
Check the Morphs list on the details screen. SampleI and BreastSize are automatically displayed from the Figure axes.
- SampleI weight: 1 (Maintain existing value)
- BreastSize weight: Set to 0.8 (via slider or numeric input)
  
  [!NOTE] In the Shape configuration screen, it is displayed as the logical name BreastSize (the physical internal management name after generation becomes PBM_BreastSize).
Click the Save to Database button at the very bottom of the screen to overwrite-save the existing morphSampleI.

Adding BreastSize to morphSampleI and overwrite-saving ▲Figure 6-13: Maintaining SampleI = 1 and setting BreastSize = 0.8 in Shapes > Morph Shapes > morphSampleI, then overwrite-saving

8. Executing Re-Generate and Updating Shape Templates

Regenerate Shape Template assets from the updated Database.

Select the Generation section from the left TreeView in ShapeSync Editor.
Keep each output relative path at default values, and click the Generate button at the bottom of the screen.
In the “Generate ShapeSync Figure” dialog, select the output root folder (e.g. Assets/ShapeSync/Generated), click “Select Folder”, and execute regeneration.
Shape Template assets directly under the output root (morphSampleI.asset, etc.) will be updated.

Specifying output destination folder in Generation and executing regeneration ▲Figure 6-14: Clicking Generate in Generation section, selecting output folder, and executing regeneration

9. Scene Placement and PBM Operation Check with Shape Director

Verify on the Figure in the Scene that PBM (BreastSize) deformation applies synchronously to both Figure and Dress.

Select the Figure (BasicFemale) placed in the Scene.
- Templates are already registered in the Template List of the ShapeDirector component from Chapter 5 (No manual re-registration is required).
Press Unity’s Play button to enter Play Mode.
- Because Auto Compile is ON by default, the latest Template is automatically synchronized initially upon entering Play Mode.
Expand Morphs under morphSampleI inside Runtime Shapes (Authoritative) of ShapeDirector.
Move the BreastSize (PBM_BreastSize) slider.
Confirm that while the walking animation continues playing, the chest of the base body (Figure) and the chest of the outfit (Dress) expand and shrink in perfect synchronization, and the outfit does not lag behind or detach.

Operating BreastSize slider and verifying synchronized chest deformation in Play Mode ▲Figure 6-15: Operating BreastSize during walking animation playback in Play Mode to confirm Figure and Dress chests deform synchronously

10. Common Issues and Solutions (Troubleshooting)

Q1. Follow BreastSize is not displayed in Dress PBM configuration screen

Cause: PBM (BreastSize) may not have been registered and saved on the Figure side.
Solution: Open Figure > PBMs first, enter PBM Name: BreastSize, assign VRMs, and press Save to Database. After saving, Follow BreastSize will be displayed when you open Outfits > Mesh Outfits > Dress1 > PBMs.

Q2. Chest does not deform or Dress does not follow when moving BreastSize in Play Mode

Cause: Generate may not have been re-executed after overwrite-saving Morph Shape (morphSampleI), or topology (polygon/bone count) may have changed during VRM export.
Solution: Confirm that you re-executed Generate in Generation of ShapeSync Editor. Also verify that polygon count, material count, and bone count of VRMs exported from VRoid Studio match the Base model exactly.

← Back to Tutorial Index ｜ ← Chapter 5: Shape Registration and Shape Director Operation Check

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