Mesh Mirror

Overview

A tool for mirroring or flipping mesh vertex positions across the X axis (YZ plane).

Key features:

• Mirror: Copy vertex positions from one side to the other (overwrite)
• Flip: Exchange left/right vertex pair positions using the symmetry table (asymmetry swaps sides)
• Single Mesh mode: Operate on left/right symmetry within a single mesh
• Dual Mesh mode: Operate between separate left/right mesh pairs
• Batch processing: Mirror / flip multiple targets at once using the same table
• Asymmetric mesh support: Two fallback methods for vertices that fail to match in the symmetry table

How to Launch

Launch the tool from the dedicated menu or with the following command.

import faketools.tools.model.mesh_mirror.ui
faketools.tools.model.mesh_mirror.ui.show_ui()

Usage

Basic Steps (Single Mesh Mode)

1. Select a symmetric base mesh in the Maya viewport and click the Set button next to Base to register it.

   

2. Select the target mesh(es) you want to mirror / flip, and click the Set button next to Target to register them. Multiple targets can be selected at once.

   

3. In the Symmetry Check section, set Method and Threshold, then click the Build Table & Check button to build the symmetry table.

4. Review the check results. If there are Failed or Asymmetric vertices, click the Select Failed Vertices button to inspect them on the base mesh.

   

5. In the Apply section, set Direction and Fallback, then click Mirror or Flip to execute. If the Create Copy checkbox is on, the target mesh will be duplicated and the result applied to the copy.

   

Flip result

Basic Steps (Dual Mesh Mode)

1. Switch Mode to Dual Mesh.

2. Register a symmetric base mesh pair in Base A / Base B.

   

3. Register target mesh pairs in Target A / Target B. The number of Target A and Target B meshes must be equal.

   

4. In the Symmetry Check section, select Method and click the Build Table & Check button to build the correspondence table from the base pair.

5. In the Apply section, set Direction and Fallback, then click Mirror or Flip to execute.

Flip result

Mesh Input Section

Register the base mesh and target meshes in this section.

• Base: The symmetric mesh used to build the symmetry table. Select a mesh in the viewport and click the Set button to register.
• Target: The mesh(es) to operate on. Select multiple meshes and click Set to register them in batch. A single mesh shows its name; multiple meshes show “N meshes”.

In Dual Mesh mode, four fields are displayed: Base A / Base B and Target A / Target B.

Note: Base and target meshes must have identical topology. If topology differs, an error is displayed when executing Mirror / Flip.

Symmetry Check Section

Build the symmetry table from the base mesh and verify its quality.

• Method: Select the table construction method (see below).
• Threshold: Set the distance threshold for vertex matching.

Click the Build Table & Check button to build the table. The following information is displayed:

Click the Select Failed Vertices button to select Failed and Asymmetric vertices on the base mesh for inspection.

Matching Methods

Single Mesh mode:

Dual Mesh mode:

Apply Section

Execute mirror or flip operations.

• Direction: Select the mirror direction.
  • Single Mesh: +X → -X (copy +X side to -X side) / -X → +X (reverse)
  • Dual Mesh: A → B (mirror A’s shape to B) / B → A (reverse)
• Fallback: Select the processing method for Failed vertices (see below).
• Create Copy: When enabled, the target mesh is duplicated before applying the result. The original target remains unchanged.

Mirror vs Flip

Mirror copies vertex positions from the source side to the destination side in one direction. The source side is not modified.

pair(neg=3, pos=58) with +X → -X:
  vtx[3] = mirror_x(vtx[58])   -- -X side overwritten by source
  vtx[58] unchanged              -- +X side stays as-is
center vertices: X snapped to 0

Flip exchanges vertex positions between left/right pairs. Both sides are modified. Asymmetric shapes swap sides.

pair(neg=3, pos=58):
  new_vtx[3]  = mirror_x(old_vtx[58])  -- positions exchanged with X mirror
  new_vtx[58] = mirror_x(old_vtx[3])
center vertices: X multiplied by -1

Fallback Methods

Processing methods for vertices that failed to match in the symmetry table (Failed). Used when left and right sides have different vertex counts.

Script Execution

The tool can be used directly from scripts without the UI.

Basic Execution

from faketools.tools.model.mesh_mirror import command

# 1. Build symmetry table
table = command.build_single_table("base_mesh", method="position", threshold=0.001)

# 2. Execute mirror
op = command.SingleMeshOperation(target="target_mesh", base="base_mesh", table=table)
op.mirror(direction="+x", fallback="closest_point")

Running a Check

# Check base mesh symmetry
result = command.get_check_result_single("base_mesh", table, threshold=0.001)
print(f"Matched: {result.matched_count}, Failed: {result.failed_count}, Asymmetric: {result.asymmetric_count}")

# Select Failed + Asymmetric vertices
command.select_failed_vertices("base_mesh", result.failed_indices + result.asymmetric_indices)

Dual Mesh Mode Execution

# Build correspondence table
table = command.build_dual_table("base_L", "base_R", method="position", threshold=0.001)

# Mirror
op = command.DualMeshOperation(
    target_a="target_L", target_b="target_R",
    base_a="base_L", base_b="base_R",
    table=table,
)
op.mirror(direction="a_to_b", fallback="closest_point")

# Flip
op.flip(fallback="laplacian")

Notes

• All calculations are performed in object space. Transform position, rotation, and scale have no effect.
• The symmetry axis is fixed to the X axis (YZ plane).
• Base and target meshes must have identical topology. A mismatch produces an error at execution time.
• Operations are undoable. Batch processing of multiple targets can be reverted with a single undo.
• Only vertex positions are modified. Normals, UVs, and other mesh attributes are not affected.