Watch Dogs: Legion — Game Engine & Modding Reference

Technical reference for WDL's engine internals, derived from DLL RE, shader analysis, and format documentation.

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1. Shader System

1.1 Shader Object Layout

engine/shaders/
├── obj/ # DX11-style compiled shader objects (.cso / .vso)
├── obj_d3d12/ # D3D12 variant (primary modding target)
├── obj_vulkan_dxc/ # Vulkan via DXC (vestigial — PC only ships DX11/D3D12)
├── fastinitdata.bin # Precompiled shader blob (DX11)
├── fastinitdata_d3d12.bin # Precompiled D3D12 blob
├── fastinitdata_vulkan_dxc.bin
└── shaders.crc # 4-byte CRC checksum

Each obj*/ has 128 hash buckets (h00–h7f). File naming: <stage>_<hash64>.<ext> (e.g. compute_132c5d0cc6f1be00.cso).

Base counts: 54,821 D3D12 shaders. Patch override: 43,065 (zero hash overlap with base — all new shaders).

1.2 DXIL Format (D3D12/Vulkan)

Both obj_d3d12/ and obj_vulkan_dxc/ files have a 0x38-byte wrapper before the standard DXBC container. Inside the DXBC is DXIL (Shader Model 6.0+). The DXBC checksum is invalid — the game bypasses validation.

Strip the header:

dd if=input.cso bs=1 skip=56 of=stripped.cso

Key properties:

• All cbuffer reads use cbufferLoadLegacy (opcode 59), zero scalar cbufferLoad (opcode 58) — early SM 6.0 scalar-CBV layout
• float[N] arrays have ArrayStride 4 (tightly packed, not vec4-aligned)
• HLSL cannot express stride-4 arrays → requires flattened cbuffer fallback

1.3 Shader Decompilation Pipeline

input.cso → strip 0x38 header → dxil-spirv → patched spirv-cross → .hlsl

Tool	Purpose
dd bs=1 skip=56	Strip D3D12/Vulkan wrapper
dxil-spirv (YYadorigi v0.6)	DXIL → SPIR-V
spirv-cross (patched)	SPIR-V → HLSL SM 6.0, with cbuffer stride-4 fix
dxc (v1.9)	DXIL disassembly / HLSL recompilation

Result: 53,545/53,551 base D3D12 shaders decompiled (99.99%). The 6 failures are non-shader files (index.*, a8e8da7e1e9c3506).

The patched spirv-cross falls back to uniform float4 _name[size] for non-packoffset-compatible arrays (SPIRV-Cross issue #2658 is wontfix upstream).

1.4 Cbuffer Member-Name Recovery

DXIL binaries retain original HLSL cbuffer member names as a string table at the end of the module. Pairing with dxc -dumpbin struct types (%dx.alignment.legacy.*) reconstructs: member name → byte offset → float4 register slot.

This is the highest-fidelity source of shader variable names — the game strips reflection names, but the string table + struct types survive.

Tools:

• cbuf_names.py — extracts <name, reg, comp, byte_offset> per cbuffer member
• rewrite_cbuffers.py — rewrites flattened float4 Viewport_c[854] → named struct

python3 rewrite_cbuffers.py <shader.cso> <decompiled/*.hlsl> <output.hlsl>

Full batch: 53,545 base shaders rewritten → decompiled_cb/. 100/100 random sample compiles via dxc -T [vs|ps|cs]_6_0 -E main.

1.5 Patch Shader Set

The patch .dat/.fat pair overrides base archives at runtime:

• Effective runtime set = base stage files + patch index (superset) + patch fastinitdata blobs
• obj_vulkan_dxc/ absent from patch — base retained entirely
• Patch index: 271,744 entries (vs 235,801 base) — ~65K new hashes
• Patch fastinitdata_d3d12.bin: 2,382,067 bytes (vs 2,092,388 base)

Content changes:

• New cbuffer layouts: 540-float4 lookup buffer in ~67% of patch compute shaders
• Skinning matrices 3066→3075, new 268/1024-size buffers
• RT reflection shaders reworked: PerInstanceData/PerInstanceAddData → single PerMaterialData buffer
• Cloth closest-hit +1,157 lines fp math, water +616, skin/hair +284

Total decompiled: 95,777 .hlsl (53,545 base + 42,232 patch).

1.6 RenderDoc Capture

The best way to get readable HLSL from live shaders:

renderdoccmd capture <Steam library>/steamapps/common/WatchDogs_Legion/bin/WatchDogsLegion.exe

Captures shaders used in a given scene (not all 170K), but is the most practical approach for modding-specific shader investigation.

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2. GLM Model Format

SportBoat_01.glm example — 31 meshes, each with 4 LOD levels:

Mesh	LOD0 verts	LOD0 faces	LOD3 verts	LOD3 faces
Chassis_LOD	3,531	599	85	550
SteeringWheels_LOD	320	641	72	79
EngineBoat_81_LOD	711	1,163	103	119
TopRack_Boat_LOD	134	249	39	28
SportRack_LOD	974	1,736	240	172
CoverTop_LOD	69	101	8	0
Inboard_LOD	70	141	4	16
Bayliner_Glass_01_LOD	41	32	26	14
Bayliner_Glass_02_LOD	41	32	26	14

LOD naming: MeshName_LOD0 (highest detail) through MeshName_LOD3 (lowest). Glass parts have only 2 LODs. Export applies -90° X-axis rotation for Blender compatibility.

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3. TAM Material Library

Materials are stored in .material.bin packs (TAM v15). Each material declares:

• Shader binding (e.g. KODOCarGeneric, KODOCarPaint, KODOGlass)
• Texture parameters with FNV-1 hashes
• 56 declared parameters per material (typical)

Shader Types

Shader	Role
KODOCarGeneric	Standard vehicle surfaces (body, rims, panels)
KODOCarPaint	Painted surfaces with clearcoat
KODOGlass	Transparent surfaces (interior + exterior)

Texture Bindings (KODOCarGeneric example)

Slot	Hash	Purpose
colour	0xF95881AF	Albedo/diffuse
specular	0x260A3CFE	Specular/roughness
normal	0x045829E2	Normal map
damage_specular	0x146C808B	Damage overlay
emissive	0x4E0D5E9	Emissive glow

Texture paths follow: graphics\vehicles_nexus\land_textures\wd2\glob*

Material archive paths reference hashed names: paulmaidens-m-9223372094509408844.material.bin

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4. Vehicle Handling Format

.handling.bin files encode vehicle physics as indexed float/uint parameters. Parsed by the game's drive handling system.

Parameter Format

Each parameter: <index> <type> <value> <name>

Index	Type	Name	Example
3	float	Length	0.3
14	float	Pitch	-20.0 (on ground)
15	float	Pitch	9643.5
17	float	Roll	3500.0
19	float	Max Spring Force Front	-1.0
25	float	Front Offset	0.0
26	float	Rear Offset	0.8
27	float	Camber Effect	0.0
35	float	Underground Length	0.25
50	float	Stiffness	2500.0
110	uint	Enable low rider	0
115	float	Suspension Speed	0.3
140	float	On Ground	-20.0
141	float	When Airborne	-20.0
505	float	Stiffness - Rear Scale	0.85
587	float	Progressivity	0.6
761	float	Raycast Extrapolation	0.0
764	float	Wall Riding Scalar	0.1

XML roundtrip: Bin → XML → edit → XML → Bin via the WDL Studio tools.

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5. Wwise Audio (WEM Format)

Sound files use Wwise (WEM) format. The game's sound directory contains WEM files indexed by numeric IDs (e.g. 1028811276.wem).

Property	Value
Format	Wwise (0xFFFF header)
Channels	2 (stereo)
Sample rate	48,000 Hz
Typical size	1–3 MB per file

Tools: vgmstream (bundled with WDL Studio), wav2wem for re-encoding. Swap workflow: drop WAV/MP3/FLAC/OGG/WEM onto highlighted clip → encode & swap.

Sound library index files map IDs to WEM files within soundbinary/.

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6. Engine Path Reference

Key paths inside the game's virtual filesystem:

Path	Contents
engine/scripts/	Lua scripts (domino engine)
engine/scripts/MissionTools.lua	Mission scripting API
engine/settings/	XML config (engine, network, threading, launch)
engine/settings/defaultrenderconfig.xml	Render settings (RT, resolution, quality)
engine/shaders/	Shader objects (see §2)
engine/shaders/Textures/SkyResource.bin	Sky LUT
engine/shaders/Textures/PuddleHeight.bin	Puddle height map
engine/gamemodes/	GameModesConfig.xml
data_win64/	Archive root (.dat/.fat pairs)
data_win64/shadersobj.dat	Shader archive
data_win64/commonengine.dat	Common engine data

Archives are split by category. filelist.txt maps paths to archives.

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7. Lua Scripting

The game uses Lua 5.1.5 with a custom "domino" visual scripting layer. Scripts are compiled to Lua bytecode but decompile cleanly (no variable/function names lost — the visual scripting tool generates standard Lua).

Globals

globals.lua contains a live dump of the _G table: 1,181 function names (e.g. SetItem, RemoveImmunity, SetNetworkVariableBool). Of these, 766 are string-locatable in the DLL (the rest are runtime-registered or packed).

LoaderWDL Integration

LoaderWDL hooks lua_pcall and luaL_loadbuffer at known RVAs (see pdb_build/build_pdb_yaml.py lines 75–82 for the dx12 offsets). The hook captures lua_state and enables injecting Lua scripts at runtime.

Console output pattern:

[UI/menu] DirectX 12 detected
[UI/d3d12] Starting d3d12 hook
Captured lua_state from pcall!
[Lua] running script...

WLU Files

WLU (compiled Lua) files require exactly 2 null bytes appended after the FCB portion or the game crashes.

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8. Archive Extraction / Repacking

Tool	Use
BE_LegionExtract.exe / BE_LegionPack.exe	GUI pack/unpack (Wine)
Gibbed.WatchDogsLegion.Unpack.exe / Pack.exe	Command-line alternative

Archives: <Steam library>/steamapps/common/WatchDogs_Legion/data_win64/

info.xml with UseCombineMode="true" enables merge installation (overlay without full archive replacement).

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9. Disrupt Engine Toolchain (from source leak)

Source: ubisoft_leak_contents.txt — 2020 Ubisoft source code leak directory listing.

The leak contains the full Disrupt engine internal toolchain used to build WDL.

Core Tools

Tool	Purpose	Key DLLs
Wolfskin	Main Disrupt engine editor (WPF)	Wolfskin.dll, WolfskinStandalone.exe, Disrupt.Core.dll, Disrupt.Controls.dll, Disrupt.Materials.Editor.dll, Disrupt.SourceControl.dll
Wolfskin Max/Maya	3ds Max + Maya DCC plugins	WolfskinMax2015.dll, WolfskinMax2017.dll, WolfskinMaya2015.nll.dll
VEdit	Vehicle handling editor	See §10.1
WatchBox	Data inspector	WatchBox.dll, WatchBase.dll, WatchDomino.dll
Painkiller	Tool (WPF-based)	Painkiller.Core.dll, Painkiller.DisruptModule.dll
Rulesmith	Visual scripting editor (93MB)	RulesmithEditor.exe, uses D3D + OpenGL ES
BlackBox	Game launcher	Contains Painkiller modules

Shader Pipeline

Tool	Platforms	Purpose
bin/DXC/PC/	PC	DXC — DXIL compiler (SM 6.0+)
bin/DXC/XboxOne/	Xbox One	DXC for Xbox
bin/DXC/Scarlett/	Xbox Series	DXC for Scarlett
bin/DXC/SPIRV/	Vulkan	DXC → SPIRV cross-compilation
bin/FXC/PC/	PC	FXC — FX compiler (SM 5.0 and below)
bin/FXC/XboxOne/	Xbox One	FXC for Xbox

Asset Pipeline

Tool	Purpose
OasisExporter	Asset export pipeline (Win32 + Win64 libs)
PakViewer	Archive (.dat/.fat) inspection
ArchiveDiffer	Diff two archive versions
MaterialEditorStandalone	Material editing (standalone)
StringIDTool	String hash/ID mapping
StreamingPNG	Streaming texture pipeline
VideoCompiler	Cutscene video compilation
VideoEncoder	ffmpeg/ffprobe for video encoding

Audio Pipeline

Tool	Purpose
WwiseAuthoring	Wwise audio authoring (full project with plugins, skins, data)
WwiseBinarizer	Wwise → binary conversion for runtime
AudioTool	Audio inspection/editing

Other Tools

Tool	Purpose
Havok/StandaloneFilterManager	Physics filter configuration
lua/	Lua tooling
FSMExport	Finite state machine export
Memory/	MemoryHUD, MemGraphViewer, MemoryService, EvilCorp, SecretService, Spy
MapExplorer	PDB/map exploration
ExcelImporter	Data import from spreadsheets
FileRenamer	Batch file renaming (uses Disrupt.SourceControl.dll)
Mosaic	Tile/asset mosaicking
DemographicPaint	NPC population painting
toolframework/	Shared tool framework plugins

Disrupt DLLs (from bin/)

DLL	Purpose
Disrupt.Core.dll	Core engine runtime
Disrupt.Controls.dll	Editor UI controls
Disrupt.Materials.Editor.dll	Material editor
Disrupt.SourceControl.dll	Perforce integration
Disrupt.AssetsHelpers.dll	Asset pipeline helpers
Disrupt.ApplicationModel.dll	Application framework
Disrupt.Services.Metadata.dll	Metadata services
RulesmithServices_r64.dll	Rulesmith backend (dx11)
RulesmithServices_r64_dx12.dll	Rulesmith backend (dx12)

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9.1 VEdit — Vehicle Handling Editor

VEdit is the Disrupt engine's vehicle dynamics editor. It contains documentation, parameter definitions, and UI layouts for car and helicopter handling.

Data Structure

VEdit/
├── Data/
│ ├── Contexts/Car/ # Chassis, Engine, Transmission contexts
│ ├── Controls/Car/ # Car UI controls
│ ├── Controls/Helicopter/ # Helicopter UI controls
│ ├── Controls/DesignSettings/
│ ├── Graphs/ # Handling curves/graphs
│ ├── Layouts/ # UI layouts
│ ├── Parameters/Car/ # Parameter definitions
│ ├── Simulation/ # Physics simulation config
│ │ ├── DefaultHandlings/
│ │ ├── Measurement/
│ │ ├── ParameterDefinitions/
│ │ └── TelemetryDefinitions/
│ └── Windows/Car/ # Editor windows
│ └── TestBezier/
├── Documentation/
│ └── html/CarHandling/ # Full handling documentation
│ ├── brakes/ + diagrams
│ ├── cameras/ + diagrams
│ ├── chassis/ + diagrams
│ ├── drag/ + diagrams
│ ├── drivetrain/ + diagrams
│ ├── engine/ + diagrams
│ ├── gearbox/ + diagrams
│ ├── graphics/
│ ├── loadtransfer/ + diagrams
│ ├── steering/ + diagrams
│ ├── surface/ + diagrams
│ ├── suspension/ + diagrams
│ ├── tutorial/
│ └── tyres/ + diagrams
└── Tool/
 └── locales/ # Multi-language support

Handling Parameters (from handling.bin)

Vehicle physics are stored as indexed float/uint parameters in .handling.bin files. Categories from VEdit documentation:

Category	Key Parameters
Chassis	Mass, centre of gravity, inertia tensor, dimensions
Suspension	Length, stiffness, damping, ride height, travel, progressivity
Steering	Lock angle, speed sensitivity, assist curve
Engine	Torque curve, RPM limits, power, flywheel inertia
Gearbox	Gear ratios, shift times, final drive
Drivetrain	FWD/RWD/AWD, differential locking, torque distribution
Brakes	Max torque, bias front/rear, ABS threshold
Tyres	Grip curve (slip angle vs friction), load sensitivity, rolling resistance
Drag	Aerodynamic drag coefficient, downforce
Surface	Terrain grip multipliers (asphalt, dirt, grass, etc.)
Load Transfer	Weight transfer during braking/acceleration/cornering
Cameras	Chase cam position, FOV, spring damping

VEdit's Documentation/html/CarHandling/ contains detailed HTML docs with diagrams for each category — the authoritative reference for handling.bin parameter semantics.