How to Balance Live2D Glue Weights to Prevent Tears at Character Joints

Glue binds overlapping vertices belonging to two ArtMeshes. Weight determines which mesh’s movement takes priority at each bound pair. At equal influence, the bound position lies midway between the two original positions; giving one mesh full priority makes the other accommodate its movement. Weights are adjustable per vertex, but cannot vary by keyform. See Live2D’s weight comparison and definitions.

Choose the intended contour before painting. At a character’s sleeve connection, for example, decide whether the sleeve edge should follow the sleeve’s existing shape closely or share the adjustment with the adjoining arm mesh. This gives each brush stroke a visual purpose.

Treat equal influence as a starting point for comparison. A useful balance is the one that preserves the intended silhouette across the poses you actually need.

Save a separate working copy, then inspect the connection in its neutral pose. Identify the short section that must remain continuous and the areas that need freedom to fold or overlap.

Cubism supports editing two selected ArtMeshes simultaneously, allowing matching geometry to be created in the same position. Its manual mesh-editing documentation also explains that a completed mesh requires connected triangular polygons.

For a new connection, use this sequence:

1. Select both ArtMeshes and enter Edit Mesh manually.
2. Create coincident vertex pairs along the intended connection while both meshes are active.
3. Check each mesh separately for texture coverage and connected edges.
4. Select the intended pairs and choose Bind.
5. Confirm mesh editing and inspect the joint in motion.

These are the essential setup steps in the official Glue instructions.

Avoid binding every overlapping point automatically. In Saraemi’s original arm-rigging demonstration, binding the entire joining area distorted the inner bend; the demonstrated setup instead bound the visible elbow section. That is a useful example of how binding extent affects a particular design, rather than a universal vertex pattern. See Saraemi’s illustrated glue walkthrough.

If topology needs revision after binding, unbind before editing, as the official manual cautions.

Select the glue object and choose Glue Weight A:B in Tool Details. This paired tool adjusts the two influences together, totaling 100%. The brush’s Weight setting controls adjustment speed: a larger percentage changes the balance faster. It is therefore different from the resulting influence ratio. These controls are documented in Tool Details: Edit Glue.

Use a brush small enough to isolate the troublesome part of the seam. Make one short adjustment, inspect the contour, and return to your comparison poses before continuing. With the paired tool, dragging strengthens the red ArtMesh’s influence; Shift-dragging strengthens the green ArtMesh’s influence. Check the displayed mesh colors rather than assuming which character part is A. See the official weight-adjustment procedure.

A practical painting loop is:

1. Hold the joint at a pose where the defect is easy to see.
2. Identify which mesh already has the more useful contour locally.
3. Shift the paired influence slightly toward that mesh.
4. Check the neighboring seam segment for a new kink.
5. Revisit neutral and the opposite movement extreme.
6. Keep the change only if the overall pose set improves.

Work along short sections instead of repainting the whole connection after each observation. Record which section you changed so an improvement at one end does not obscure a regression elsewhere.

First inspect the active tool. Glue Weight A changes the red mesh independently, and Glue Weight B changes the green mesh independently. Re-merge Glue Vertices Tool recombines vertices separated by those adjustments. Its brush must cover the relevant vertices. See Cubism’s glue tool definitions.

For a connection intended to stay closed, try re-merging the affected pairs, then resume with A:B. Inspect the same pose immediately afterward. This makes the repair easy to evaluate before further painting changes the evidence.

Use the following diagnostic order as an editorial workflow derived from the documented controls:

Observation	First check	Next action
A seam opens immediately after painting	Active brush and separated pairs	Re-merge affected pairs, then test A:B
The seam stays connected but develops a bulge	Which side dominates locally	Make a small paired-weight adjustment
The inner bend bunches across a broad area	Extent of the bound region	Reconsider which pairs need binding
A fix works in one pose but fails elsewhere	Full pose set	Compare weights and underlying forms before committing

Select the glue object to access Compatibility in the Inspector. This controls the degree of glue application, and it can be assigned parameter keys with different values. Live2D documents that behavior in Inspector palette: Display When a Glue Is Selected.

Keep Compatibility consistent while establishing the vertex balance. This is a recommended working method: changing influence and overall application simultaneously makes it harder to tell which adjustment improved the joint.

Consider keyed Compatibility when your intended animation calls for a different amount of attachment at different poses. Before changing it, write down the desired behavior: which pose needs stronger attachment, which needs less, and what should happen between them. Then inspect the transition as carefully as the endpoints.

Do not use a Compatibility change as your first response to one misshapen seam vertex. Start with the local connection and influence checks so the correction addresses the observed defect.

Build a small pose matrix before fine tuning. The following values are illustrative test positions expressed as fractions of your existing parameter range; they are not prescribed Cubism settings.

Test	Suggested positions	What to inspect
Main joint movement	Minimum, quarter, midpoint, three-quarter, maximum	Separation and contour changes
Joint plus another relevant parameter	Joint minimum and maximum with the other parameter at both extremes	Combined deformation
Return to neutral	Default parameter values	Whether the original shape still reads correctly
Slow continuous sweep	Entire intended movement	Abrupt changes between sampled poses

Use the same test order after each meaningful adjustment. First inspect closely for a gap, then view the character at its intended display size to judge the silhouette. A simple note such as “outer connection improved; inner fold worsened at maximum” is more actionable than “looks better.”

If every weight change merely moves the distortion elsewhere, revisit the mesh forms and binding extent. Saraemi’s walkthrough also discusses adjusting ArtMesh deformation when refining the connection, providing a concrete example of correction beyond weight painting. See the original joint-shaping demonstration.

Finish when the intended connection remains continuous, the contour holds through the required pose combinations, and the neutral form still matches the design. Keep the tested pose set with your working notes so later rig changes can be checked against the same standard.

• Glue — Editor Manual | Live2D Manuals & Tutorials
• Edit Mesh manually — Editor Manual | Live2D Manuals & Tutorials
• Tool Details palette — Editor Manual | Live2D Manuals & Tutorials
• Inspector palette — Editor Manual | Live2D Manuals & Tutorials
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