Instant Remesh — Modly Extension

Retopologizes any 3D mesh into clean quad or triangle topology using Instant Meshes.

Extension ID: instant-meshes
Version: 3.0.0
Author: Lorchie
Runtime: Python + Instant Meshes CLI binary (CPU)

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Pipeline

GLB input
  └─ 1. Load GLB        ──  trimesh, merges all primitives
  └─ 2. Repair          ──  fix winding, fill holes, remove degenerate/duplicate faces
  └─ 3. GLB → OBJ       ──  temp file for Instant Meshes
  └─ 4. Instant Meshes  ──  orientation field + remesh
  └─ 5. OBJ → GLB       ──  recomputes normals, exports

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Parameters

Parameter	Default	Description
target_faces	5 000	Target face count. -1 = auto (preserves original density)
topology	quads	quads for animation/subdivision, triangles for game-ready assets
crease	25°	Dihedral angle above which edges are preserved as sharp
smooth	2	Instant Meshes internal smoothing passes

Tuning tips

Situation	Recommendation
Organic character	topology quads, crease 20°, smooth 3
Creature with fine detail	target_faces -1, crease 15°, smooth 2
Subdivision-ready	topology quads, target_faces -1, smooth 3
Game engine asset (organic)	topology triangles, target_faces 3 000–8 000

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When to use

Use case	Result
Organic mesh (character, creature, plant)	Clean quad retopology for animation or subdivision
Dense mesh needing face reduction	Intelligent decimation with controlled face count

When NOT to use

Use case	Why
Hard-surface mesh (building, armor, furniture)	Orientation fields diverge at corners → artifacts
AI-generated mesh with non-manifold geometry	Holes and artifacts even after repair
Mesh already clean and usable	No benefit — may add noise

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Known limitations

• Non-manifold meshes — self-intersections or open borders degrade results. The repair step mitigates but cannot fix fundamental topology issues.
• Hard-surface geometry — right angles and flat planes cause orientation field noise. Use a dedicated decimation tool instead.
• Fine detail loss — use target_faces -1 or a high count to preserve detail.
• Processing time — large meshes (>200k faces) can take several minutes on CPU.

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Requirements

Dependencies are installed automatically by setup.py in an isolated venv.

Package	License	Description
trimesh	MIT	GLB/OBJ read, write & repair
numpy	BSD	Numerical arrays
scipy	BSD	Required by trimesh for OBJ export
Instant Meshes binary	BSD-3-Clause	Remesh engine (bundled for Windows)

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Project Structure

modly-instant-meshes/
├── manifest.json     # Modly manifest (node declaration, parameters)
├── processor.py      # Main processor
├── setup.py          # Install script — creates venv, installs deps
├── bin/
│   └── instant-meshes.exe   # Windows binary (bundled)
└── .gitignore

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Credits

Resource	Link
Instant Meshes	github.com/wjakob/instant-meshes
trimesh	github.com/mikedh/trimesh

Instant Meshes — Jakob, Wenzel et al. — Instant Field-Aligned Meshes — SIGGRAPH Asia 2015

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License

Instant Meshes — BSD 3-Clause
trimesh — MIT