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Legion Leak — Havok 2017.2 Primitive Files

Key Finding​

The primitive HKX files in the Legion leak at data_win64/generated/primitives/ are Havok 2017.2 (SDKV 20170200@). They use the TAG0 format (not the old packfile format) and contain the exact compressed mesh classes needed.

File Locations​

  • data_win64/generated/primitives/prim_4_*.hkx — 9 files, ~8KB each
  • Format: TAG0/SDKV/DATA/TYPE/INDX/ITEM/PTCH chunks
  • SDK version: 20170200@ (Havok 2017.2.0)

Classes Found in Primitive Files​

  • hknpCompressedMeshShape — the collision shape
  • hknpCompressedMeshShapeData — contains the mesh tree + connectivity
  • hknpCompressedMeshShapeTree — the mesh tree with sections/primitives
  • hknpCompressedMeshShapeTreeDataRun — the data run entries
  • hkcdStaticMeshTreeBase — the base tree class
  • hkcdStaticMeshTreeCommonConfig — tree configuration

TAG0 Format Structure​

+0x00: header (flags + size + magic)
+0x04: hash
+0x08: total size
+0x0c: flags
+0x10: TAG0 magic
+0x14: SDKV chunk (SDK version string)
+0x1c: DATA chunk (serialized objects)
+0x4b0: TYPE chunk (class definitions)
+0xb72: ITEM chunk (item metadata)
+0x20a8: INDX chunk (index data)
+0x2148: PTCH chunk (patch data)

Next Steps​

  1. Parse the TYPE section to extract class member layouts for hknpCompressedMeshShapeTree
  2. Map the binary layout to the HKLib C# class definitions
  3. Use this to decode the compressed mesh triangle bitstream
  4. Build a decoder for the WD1/WD2/WDL compressed mesh format

Importance​

These files are Havok 2017.2 — the exact version WDL uses. The hkCompatFormats.dll from 2017.2 would be needed for packfile serialization, but these primitive files show the CLASS LAYOUTS which are version-specific. This is the missing piece for understanding the compressed mesh format.