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WD1/WD2/WDL Compressed Mesh Format (Havok 2017.2)

Source​

Class definitions extracted from prim_4_10252363098235285984.hkx in the Legion leak using hkxparser (Havok 2017.2, SDKV 20170200@).

Class Hierarchy​

hknpCompressedMeshShape (144 bytes, align 16)
 └─ m_data: hknpCompressedMeshShapeData (256 bytes, align 16)
 ├─ m_meshTree: hknpCompressedMeshShapeTree (160 bytes, align 16)
 │ └─ extends hkcdStaticMeshTree (160 bytes)
 │ ├─ packedVertices: hkArray<uint32> (+0x70)
 │ ├─ sharedVertices: hkArray<uint64> (+0x80)
 │ └─ primitiveDataRuns: hkArray<PrimitiveDataRun> (+0x90)
 ├─ m_simdTree: hkcdSimdTree (16 bytes)
 └─ m_connectivity: hkcdStaticMeshTreeBase::Connectivity (48 bytes)
 ├─ headers: hkArray<SectionHeader>
 ├─ localLinks: hkArray<uint8>
 └─ globalLinks: hkArray<uint32>

Key Structures​

hkcdStaticMeshTreeBase (112 bytes, align 16)​

+0x30: int32 numPrimitiveKeys
+0x34: int32 bitsPerKey
+0x38: uint32 maxKeyValue
+0x3c: uint8 primitiveStoresIsFlatConvex
+0x40: hkArray<Section> sections
+0x50: hkArray<Primitive> primitives
+0x60: hkArray<uint16> sharedVerticesIndex

Section (96 bytes, align 16)​

+0x30: float[6] codecParms (quantization: AABB min/max)
+0x48: uint32 firstPackedVertex (index into packedVertices)
+0x4c: uint32 sharedVertices (index into sharedVerticesIndex)
+0x50: uint32 primitives (index into primitives array)
+0x54: uint32 dataRuns (index into primitiveDataRuns array)
+0x58: uint8 numPackedVertices
+0x59: uint8 numSharedIndices
+0x5a: uint16 leafIndex
+0x5c: uint8 page
+0x5d: uint8 flags
+0x5e: uint8 layerData
+0x5f: uint8 unusedData

PrimitiveDataRun (4 bytes)​

+0x00: uint16 value (data run value)
+0x02: uint8 index (data run index)
+0x03: uint8 count (data run count)

hknpCompressedMeshShapeData (256 bytes)​

+0x20: hknpCompressedMeshShapeTree meshTree (160 bytes inline)
+0xc0: hkcdSimdTree simdTree
+0xd0: Connectivity connectivity (48 bytes inline)

Connectivity (48 bytes)​

+0x00: hkArray<SectionHeader> headers
+0x10: hkArray<uint8> localLinks
+0x20: hkArray<uint32> globalLinks
SectionHeader: {uint32 baseLocal, uint32 baseGlobal} (8 bytes each)

Key Differences from HKLib (2018)​

  • HKLib uses PrimitiveDataRun with m_value(u16) + m_index(u8) + m_count(u8)
  • Binary format uses PrimitiveDataRunData (u16) + index(u8) + count(u8) — same layout!
  • Section layout matches our earlier analysis but with confirmed field names
  • numSharedIndices at +0x59 (NOT numPrimitives as previously assumed)