Model Codex

A desktop tool to browse, preview, and export 3D models (with their mapped textures) from Bungie's Marathon (2025) — the third in a series alongside texture-codex and audio-codex, in the spirit of Deimos, MIDA, and Charm.

It reads the game's Tiger Engine .pkg packages directly (AES‑128‑GCM + Oodle), decodes the static render‑model geometry, couples each mesh part to its material's textures, and lets you preview models in an interactive 3D viewport and export to glTF / OBJ / FBX / STL — for Blender, CAD, and other DCC tools.

Own, clean‑room implementation. The Marathon model format was reverse‑engineered with the bundled Probe harness and validated against retail data and external tools. No code from Deimos / MIDA / Charm is vendored or copied — they were used only as documentation of the file format.

Features

• Browse the static‑model catalogue (~54,000 models) by package (outpost, marathon_deck_001, perimeter, sr_gear, …), each grid cell showing the actual model in an isometric view that orbits as you hover.
• Live 3D preview of the selected model with its in‑game materials/textures, plus a channels list of the resolved texture maps.
• Open in a tab for a full interactive inspector — orbit camera (perspective by default, isometric toggle), textured / wireframe / grid toggles, FOV, and a view cube.
• Export a model — or a whole package in bulk — to glTF 2.0 (.glb, textures embedded), OBJ + MTL, FBX, or STL, namespaced by category. Set the default format and export folder in Settings.

Requirements

• Windows x64 and a .NET 8 desktop runtime, or a self‑contained build (below).
• A local Marathon install — the tool uses the game's own bin\x64\oo2core_9_win64.dll (Oodle) to decompress packages. Nothing from the game is redistributed.

Running

Run.bat            # builds + launches the Release build

or from source:

dotnet run --project src/App/ModelCodex.App.csproj -c Release

On first launch the game folder is auto‑detected at A:\Steam\steamapps\common\Marathon. If yours is elsewhere, open Settings → Browse… and pick the Marathon install folder (the one containing packages\ and bin\).

Setup / packaging

C#/.NET 8 + WPF with HelixToolkit.SharpDX for the DirectX‑11 viewport — export via SharpGLTF (glTF) and Assimp (FBX). The Tiger package layer is shared with texture‑codex.

• Fresh machine, from source: powershell -ExecutionPolicy Bypass -File scripts\setup.ps1
• Standalone, no .NET install needed: powershell -ExecutionPolicy Bypass -File scripts\publish.ps1 produces a self‑contained build in publish\.

How it works

.pkg (Tiger Engine packages, header v53)
  ↓ TigerPackage  — AES-128-GCM block decrypt + Oodle (oo2core_9) decompress
static model tag (type 8, class 0x80808635 = SStaticMesh)
  ↓ StaticMesh.Parse — SStaticMesh → SStaticMeshData → parts / buffer groups
vertex buffer (32/4 header {DataSize, Stride, Type}) + index buffer (32/6 header)
  ↓ decode packed int16 positions → × ModelTransform; UVs → × TexcoordScale
material (type 8) → texture refs (scan + hash64) → TigerTexture decode (BCn / RGBA)
  ↓
HelixToolkit Viewport3DX preview · isometric grid thumbnails · glTF/OBJ/FBX/STL export

The package reader (src/Tiger/TigerPackage.cs, Oodle.cs) and texture decode (TigerTexture.cs) are shared with texture‑codex; the model layer (src/Tiger/Model/) is new. The format offsets were reverse‑engineered against the retail packages — see src/Probe for the discovery harness (hist, model, mesh, stats, thumb, texmodel).

Fonts

The in‑game typefaces (PP Fraktion Mono, MarathonShapiro Wide 65) are extracted from Marathon and not redistributed; they're git‑ignored. The app falls back to a system font if absent. To restore the in‑game look, drop the .otf files into src/App/Assets/Fonts/.