DeadMesh - MOPP Collision Validator

Description

Some collision meshes hold a small search tree that points the physics engine at a triangle. If that tree points at a triangle that does not exist (bad export, broken collision regen, sloppy port), the engine reads memory it should not. You get an invisible wall, a stutter, or a crash to desktop with no error and no hint which mod caused it.

DeadMesh reads your meshes (loose .nif files and meshes inside .bsa archives), checks every collision triangle the engine could reach, and tells you which meshes are broken and whether each one can crash you or just glitch. No game launch needed.

DeadMesh does not guess. It runs Havok's own collision math offline: it reimplements the engine's MOPP bytecode and triangle decoder and walks the collision tree itself, the same way the game does at runtime. Then it goes further than the game ever can. In play the engine only resolves the few triangles a single step or hit actually touches. DeadMesh visits every branch and every triangle the mesh can ever produce, from every side, in one pass. If none of them read out of bounds, the mesh is proven safe against this crash. If even one does, that mesh was a crash waiting for the right angle.

Using the app

1. Run DeadMesh.exe.

2. Pick a path: a folder (your Data\meshes, an MO2 mods tree, a single mod) or one .nif.

3. Options:

- Search models in BSA archives: also scan meshes inside .bsa (on by default).

- Multi-core: use every CPU core (faster on big scans).

- Show clean / no-MOPP: also list healthy meshes (off by default, so you see only problems).

- Language: English or Russian or Chinese - Special thanks to 899606070422 for the Chinese translation!

4. Press Scan. Rows appear most dangerous first.

5. Click a row to read a plain explanation.

6. Export report saves the full detail to .csv, .jsonl, .txt.

Requirements:

Windows 10 or 11, 64-bit. Portable, no install needed: unzip the whole folder and run DeadMesh.exe. Built for Skyrim SE, AE, VR meshes.

What the verdicts mean

CRASH RISK (red) - Broken collision that can crash the game. Fix or remove this mesh.

BROKEN COLLISION (orange) - Garbage collision triangle. Usually an