XeNTaX Forum — Havok Knowledge Extract

Extracted from xentax.sql forum dump (2026-08-19). Focused on knowledge NOT already covered in reference/havok/hkx_format.md or reference/havok-repos.md.

1. Havok Version History & Game Mapping

Source: t=11155 (Havok Engine Animations), t=12424 (HAVOK *.hkx), t=12857 (Havok binary files)

Havok Version	Packfile Version	Games	Notes
4.1.0-r1	—	Bioshock 1/2	Very old, archaic format
6.5	—	Sleeping Dogs (original)	Binary mode
hk_2010.2.0-r1	8	Skyrim LE/SE, Dark Souls 1	Best tool support (hkxcmd, SSFADF)
hk_2011.2.0-r1	9	Sleeping Dogs (original)	Very similar to 2010
hk_2012.2.0-r1	9	Alien: Isolation	SSFADF supports up to this
hk_2013.1.0-r1	9	Sleeping Dogs DE (Definitive Edition)	Havok Content Tools version
hk_2013.2.0-r1	11	Dark Souls II/III, various	Major header changes vs 2010
hk_2014.1.0-r1	11	FO4, Witcher 2, AC games	Havok Content Tools 2014.1

Key insight (SergeantJoe, t=12857): The 2010 and 2013 formats are "practically the same" except for a small header prefix. Multiple animations per file appear in 2011+ (single hkx per file in 2010).

2. Packfile Header Differences (Version 9 vs 11)

Source: t=12857 Post 97 (JohnHudeski), hkx_format.md

Packfile version 9 (2010–2012):

int32 misc;
int32 pad[1];

Packfile version 11 (2013+):

int32 misc;
int16 m_maxPredicates;
int16 unkn;
int32 pad[4];

Version 11 adds 16 extra bytes of header padding. The --strip flag on AssetCc1 removes "extra junk at the start of the file" (SergeantJoe, Post 68).

3. Tool Reference (Historical & Current)

hkxcmd (figment)

URL: https://github.com/figment/hkxcmd
Supports: hk_2010.2.0-r1 only
Converts: HKX ↔ XML
Limitation: Takes 2011 files silently but writes nothing. Does not decompress spline animations.
Workaround: Rename version string from 2011→2010 to force processing (partial success)

havok2fbx (Highflex)

URL: https://github.com/Highflex/havok2fbx/releases
Supports: hk_2014.1.0-r1 only (specifically stated)
Converts: HKX → FBX
Workaround: Rename version from 2010→2014 to force processing

SSFADF / dark_souls_hkx (Danilodum/Snaz)

URL: https://github.com/Danilodum/dark_souls_hkx/releases
Supports: Up to hk_2012.2.0-r1
Converts: HKX animations → .damnhavok XML
Usage: Place exe in animation directory, double-click (recursively processes all .hkx except Skeleton.hkx)
Limitation: Does not work on 2013+ files ("bad file")

Volfin's hkx2smd

URL: https://bitbucket.org/Volfin/hkx2smd/overview
Language: C#
Supports: 2010.2.0 and 2012.2.0
Converts: HKX → SMD (skeleton only)
Key code location: Program.cs has file structure definitions at the top
Note: Crashes on 2014+ files (1.5 billion element array error). Developers modified it per-game.

AssetCc (Havok SDK tools)

Location: hkSDK_Root\Tools\BatchProcess\AssetCc
Usage:

AssetCc1.exe --strip bin.hkx xml.hkx # binary → XML
AssetCc1.exe --strip --rules8011 xml.hkx bin.hkx # XML → binary

Cc1 vs Cc2: Cc1 keeps original version number; Cc2 converts to the version the exe was built with.
Rules: --rules4101 (Win32 x64) vs --rules8011 (Win32 x86) — different binary output
Limitation: AssetCc from 2014 SDK rejects 2013.2.0 files with "Unsupported file format"

Havok Standalone Tool (ToolStandAlone.exe)

Supports: Visualization and XML export of HKX files
Limitation: "Wrong platform for packfile" error with many game files
Workaround: Import skeleton + animation, then export

hkxpack (Dexesttp)

URL: https://github.com/Dexesttp/hkxpack
Converts: HKX binary → Tag-XML (not regular XML)
Note: Tag-XML is different from regular XML; hkxcmd cannot read it

Havok Content Tools (3ds Max plugin)

Use: Export animations as spline compressed or uncompressed for comparison
Location: Available via Intel Havok site (now defunct, Microsoft acquired)
Key use case: Create reference hkx files to compare headers with game files

4. hkaSplineCompressedAnimation Deep Dive

Source: t=12857, t=11155, t=4066

Animation Type Enum

enum hkaAnimation::AnimationType {
 HK_UNKNOWN_ANIMATION = 0x0,
 HK_INTERLEAVED_ANIMATION = 0x1,
 HK_MIRRORED_ANIMATION = 0x2,
 HK_SPLINE_COMPRESSED_ANIMATION = 0x3,
 HK_QUANTIZED_COMPRESSED_ANIMATION = 0x4,
 HK_PREDICTIVE_COMPRESSED_ANIMATION = 0x5,
 HK_REFERENCE_POSE_ANIMATION = 0x6,
};

TrackCompressionParams (from PBD analysis, SergeantJoe)

struct hkaSplineCompressedAnimation::TrackCompressionParams {
 float m_rotationTolerance;
 float m_translationTolerance;
 float m_scaleTolerance;
 float m_floatingTolerance;
 unsigned __int16 m_rotationDegree;
 unsigned __int16 m_translationDegree;
 unsigned __int16 m_scaleDegree;
 unsigned __int16 m_floatingDegree;
 hkEnum<RotationQuantization, unsigned char> m_rotationQuantizationType;
 hkEnum<ScalarQuantization, unsigned char> m_translationQuantizationType;
 hkEnum<ScalarQuantization, unsigned char> m_scaleQuantizationType;
 hkEnum<ScalarQuantization, unsigned char> m_floatQuantizationType;
};

Quantization Types

enum RotationQuantization {
 POLAR32 = 0x0, // 32-bit: 10-bit magnitude + 18-bit phi/theta
 THREECOMP40 = 0x1, // 40-bit: three 11-bit components
 THREECOMP48 = 0x2, // 48-bit: three 15-bit components
 THREECOMP24 = 0x3, // 24-bit
 STRAIGHT16 = 0x4, // 16-bit quat: 8-bit components
 UNCOMPRESSED = 0x5, // 4x float32
};

enum ScalarQuantization {
 BITS8 = 0x0,
 BITS16 = 0x1,
};

Default Havok Spline Compression Settings (philgrf, t=12857 Post 80)

Position: 16 bits
Rotation: 40 bits (THREECOMP40)
Scale: 16 bits
Float: 16 bits
Frames per block: 256

Critical note: Compression is highly customizable per-bone. The defaults are just a starting point. Per-bone customization allows grouping bones by hierarchy depth for different compression levels.

Quaternion Encoding (philgrf, Post 78)

Rotation stored as quaternion (x, y, z, w)
Highest magnitude component discarded (since x²+y²+z²+w²=1)
Remaining 3 components encoded with quantization bits
Reference: Riot Games engineering blog on spline compression, Bitsquid blog

5. Known Issues & Workarounds

Version String Manipulation (SergeantJoe, t=12857)

Files from games often have extra data before the "WaaW" magic:

// To process: cut data before "WaaW", rename version string
// 2011 → 2010 for hkxcmd
// 2010 → 2014 for havok2fbx

Each tool only supports specific versions, but the underlying format is often identical.

Header Replacement Strategy (shakotay2, t=12857)

Create a reference hkx file using Havok Content Tools + 3ds Max
Compare headers between reference and game file
Identify which header bytes differ
Replace game header with reference header (carefully)

Animation Swap (SergeantJoe, Post 70)

To swap animations that are already in-game:

Replace data starting with "WaaW" and ending with "+ yyyyyy"
The two header numbers before "WaaW" are memory size pointers
Set them to minimum possible values to avoid crashes

blendHint Fix (SergeantJoe, Post 67)

Changing hkaAnimationBinding.blendHint from NORMAL to ADDITIVE can reveal animation data that appears "locked" during conversion.

Platform Flag Issues (Loomy, Post 88)

public enum hkPlatform {
 HCL_PLATFORM_WIN32 = 0x0,
 HCL_PLATFORM_X64 = 0x1,
 HCL_PLATFORM_PS3 = 0x10,
 HCL_PLATFORM_XBOX360 = 0x20,
 HCL_PLATFORM_WII = 0x40,
 HCL_PLATFORM_LINUX = 0x100,
 HCL_PLATFORM_ANDROID = 0x800,
 // ...
}

PS3/big-endian files require byte-swapping for all multi-byte values.

6. Disrupt Engine HKX specifics (from xentax)

Source: t=12424 (Oleg's post about Ubisoft Disrupt)

Vehicle physics hkx files contain: hkpRigidBody, hkpListShape, hkpConvexVerticesShape, hkpConvexVerticesConnectivity, hkpCylinderShape, hkpConvexTransformShape, hkpBoxShape, hkpConvexTranslateShape, hkpConstraintInstance, hkpLimitedHingeConstraintData, hkpPositionConstraintMotor, hkpStaticCompoundShape, hkpBvCompressedMeshShape
Geometry file (.xbg) contains pre-defined vertex deformation data
hkx file may contain mapping of physical volume to geometry vertices (hit/damage on collision → visual deformation)
Skeleton is external: Each model has a "reference skeleton" file (XML converted to binary), included for reference only — damaging it doesn't affect gameplay
nomadVehiclePhysResourceData class wraps all vehicle physics

7. Convex Mesh Decomposition for Collision

Source: t=18206 (Bloodborne collision), t=11434 (Killzone meshes)

Havok packfiles saved on 32-bit machines with big-endian integers (PS3 games)
Packfiles are NOT cross-platform — require exact same layout rules to load
Old packfiles need versioning enabled (deprecated in newer SDKs)
For long-lasting assets, Havok recommends tagfiles over packfiles

hkpBvCompressedMeshShape

Used for compressed collision meshes. Contains:

Vertices (can be quantized)
Face indices
Connectivity data
Bounding volume hierarchy

8. Practical Workflow Summary

Extracting Skeleton from HKX

Best tool: Volfin's hkx2smd (C#, source available)
Manual: shakotay2's method (search for bone names, extract transforms)
Alternative: hkxcmd (2010 files only)

Extracting Animations from HKX

2010 files: hkxcmd → XML → Havok Standalone Tool
2012 files: havok2fbx (with version rename), or SSFADF
2013+ files: No reliable method exists as of 2022
Workaround: Use Havok Content Tools to create reference animations, compare with game files

Converting HKX → 3D Software

HKX → SMD (Volfin's hkx2smd) → Blender/Max/Maya
HKX → FBX (havok2fbx) → any 3D software
HKX → XML (AssetCc/hkxcmd) → Havok Standalone Tool → export

9. Key Repository Links

Tool	URL	Supports
hkxcmd	https://github.com/figment/hkxcmd	2010
havok2fbx	https://github.com/Highflex/havok2fbx	2014
dark_souls_hkx	https://github.com/Danilodum/dark_souls_hkx	≤2012
hkx2smd (Volfin)	https://bitbucket.org/Volfin/hkx2smd	2010, 2012
hkxpack	https://github.com/Dexesttp/hkxpack	Tag-XML
HavokLib (PredatorCZ)	https://github.com/PredatorCZ/HavokLib	5.0–2017
botw_havok	https://github.com/krenyy/botw_havok	Python parser

10. Attribution

Key contributors from XeNTaX:

SergeantJoe — Extensive 2013 format analysis, animation swap technique
shakotay2 — Manual skeleton extraction, header comparison methodology
JohnHudeski — SDK demo code for animation conversion, format analysis
Bastien — Early 2010 format analysis, AssetCc documentation
Snaz (Danilodum) — Dark Souls HKX tools, SSFADF converter
Volfin — hkx2smd C# converter (Alien: Isolation)
philgrf — Spline compression theory and documentation analysis
Oleg — Disrupt engine HKX structure analysis (vehicle physics)
Loomy — Big-endian/PS3 parsing, platform flags, hkxpack integration
HunterAP — Dark Souls III format testing, 64-bit pointer issues

1. Havok Version History & Game Mapping​

2. Packfile Header Differences (Version 9 vs 11)​

3. Tool Reference (Historical & Current)​

hkxcmd (figment)​

havok2fbx (Highflex)​

SSFADF / dark_souls_hkx (Danilodum/Snaz)​

Volfin's hkx2smd​

AssetCc (Havok SDK tools)​

Havok Standalone Tool (ToolStandAlone.exe)​

hkxpack (Dexesttp)​

Havok Content Tools (3ds Max plugin)​

4. hkaSplineCompressedAnimation Deep Dive​

Animation Type Enum​

TrackCompressionParams (from PBD analysis, SergeantJoe)​

Quantization Types​

Default Havok Spline Compression Settings (philgrf, t=12857 Post 80)​

Quaternion Encoding (philgrf, Post 78)​

5. Known Issues & Workarounds​

Version String Manipulation (SergeantJoe, t=12857)​

Header Replacement Strategy (shakotay2, t=12857)​

Animation Swap (SergeantJoe, Post 70)​

blendHint Fix (SergeantJoe, Post 67)​

Platform Flag Issues (Loomy, Post 88)​

6. Disrupt Engine HKX specifics (from xentax)​

7. Convex Mesh Decomposition for Collision​

hkpBvCompressedMeshShape​

8. Practical Workflow Summary​

Extracting Skeleton from HKX​

Extracting Animations from HKX​

Converting HKX → 3D Software​

9. Key Repository Links​

10. Attribution​