Skip to content

PHASE2.md

Latest commit

 

History

History
137 lines (118 loc) · 6.55 KB

PHASE2.md

File metadata and controls

137 lines (118 loc) · 6.55 KB
Raw

ArkWeb Phase 2: Gotham collision inside Spider-Man

2a. Arkham Knight geometry export: working (2026-10-01)

The AK host has dev commands (logs/ak_cmd.txt, see src/ak_host/devcmd.h). They run on the game thread, or on the worker while AK is paused for lost focus.

PhysX 3.3.1 access without the SDK (src/ak_host/px.h)

  • Vtable slots were recovered from PhysX's reflection metadata (tools/px_meta.py) and checked in disassembly:

    • PxPhysics: getNbScenes 23, getScenes 24
    • PxScene: getNbActors 17, getActors 18. The actor-type flags go by pointer. Passing the value crashed the game once.
    • PxRigidActor: getGlobalPose 20 (hidden return), getNbShapes 25, getShapes 26
    • PxShape: getGeometryType 5, getLocalPose 17 (hidden return)

  • Geometry comes from the exported PxShapeGeometryPropertyHelper::getGeometry overloads (this unused, shape in rdx, output struct in r8). PxConvexMeshGeometry is 0x28 bytes with the mesh pointer at +0x20.

  • Convex hull data is in the mesh object at +0x20:

    Offset Field
    +0x20 AABB (6 floats)
    +0x38 centre of mass
    +0x44 u16 nbEdges
    +0x46 u8 nbVerts
    +0x47 u8 nbPolys
    +0x48 polygons pointer (20 bytes each); the vertices follow the polygons

    The layout was confirmed on 3 meshes (box hull: 12/8/6), and all vertices lie inside the AABB.

  • Triangle meshes: layout detected per mesh (only 2 exist).

Gotham's static collision

  • 39,092 static actors with 73,711 shapes: 39,000 convex, 34,709 boxes, 2 triangle meshes.
  • 5 scenes; scene 0 holds 39k of the static actors.
  • Scale: 0.02 PhysX units per UU (1 PhysX unit = 50 UU = 0.5 m).

First export (logs/gotham_150m.obj, rendered to gotham_150m_view.png / _top.png)

  • 42,237 shapes within 150 m of Batman. Offline that's 594k triangles once the convex hulls are rebuilt (scipy).
  • Only 3 of 38,997 convexes were unreadable.
  • Recognisable Gotham: buildings, smokestacks, cranes, bridges, rooftops.

2b. Next: Spider-Man side

  • Stream shapes host -> guest over the collision ring as convex point sets and boxes (guest space) and instance them near the hero.
  • Build Havok shapes in Spider-Man (hknpConvexPolytopeShape from points, or a compressed mesh from hkGeometry), add them as static bodies, and filter the hero's queries to Gotham only.

2b. Spider-Man runtime collision: static RE so far (Spider-Man.exe 4.0630)

The template is TerrainPhysics::CreateTile @ 1998230, the game's own path for adding static collision at runtime (recon/sm_terrain_createtile.asm).

Steps CreateTile follows

  1. Shape. A heightfield in CreateTile. For Gotham:

    • Box: hknpConvexShape::createFromHalfExtents @ 2e44130 (rcx = const hkVector4* halfExtents, xmm1 = radius, r8 = const hkTransform* or null). It allocates 0x1d0 bytes from the Havok heap and constructs an hknpBoxShape.
    • Convex: hknpConvexShape::createFromVertices @ 2e44410 (rcx = hkStridedVertices* {ptr, int count, int stride 16}, xmm1 = radius, r8 = BuildConfig*).
      • BuildConfig (≥0x30 bytes) gets its defaults from the ctor @ 2e43670. Havok's own caller then sets byte +0x11 = 0 and byte +0x2d = 0. +0x20 is a transform pointer (null = none).
      • Havok assert: "Couldn't create and simplify the hull from provided vertices".

  2. hknpPhysicsSystemData, built by hand at block+0x80 (refcounted object):

    Offset Field
    +0x00 vtable exe+3d022d8
    +0x08 0
    +0x10 qword 0x1ffff, then u16 0xffff
    +0x18 hkArray materials (0x70 each)
    +0x28 motionProperties (0x70)
    +0x38 bodyCinfos (0xB0)
    +0x48 constraints
    +0x58 referenced objects (8)
    +0x68 name
    +0x70 byte 1
    • hkArray = {ptr, int size, int capacityAndFlags}; 0x80000000 = don't deallocate.
    • Arrays grow with 2aee6e0(allocator=2adc520(), &array, elemSize).

  3. Material. Default ctor 2e25800; name 2aeecd0; +0x28 = 0, +0x38 byte 2, +0x39 byte 2, +0x3C float = [exe+382e120]. Copied into the array with 2e257a0.

  4. Motion properties. 0x70 bytes copied from the preset at [[[exe+609a570]+0x18]+0xa20]+0x30.

  5. Body cinfo (0xB0). Default ctor 2e24b30, then:

    Offset Field
    +0x00 shape*
    +0x10 collisionFilterInfo = 0x243f (terrain)
    +0x14 u16 material index 0
    +0x18 hkStringPtr name
    +0x20 userData
    +0x28 byte 0
    +0x30 position (vec4)
    +0x40 orientation (quat xyzw)
    +0x70 float [exe+382f0e4]
    +0x78, +0x90 refptrs
    +0xA0 int -1

  6. Shape added to the data's referenced objects (+0x58, addReference 2aee150); name at +0x68 from [exe+6208438].

  7. Add to the world.

    • Construct: hknpPhysicsSystem::hknpPhysicsSystem(this = 0x50-byte block, world = [[exe+609a570]+0x18], data, transform = &[exe+6b14af0] (identity), flags 3) @ 2e400c0
    • Add: 2e410d0(system, 1, 0)

Still to resolve

  • That [[exe+609a570]+0x18] is the same world as the query hook's [exe+78939e8].
  • Query filter. Every hero query carries hknpCollisionFilter* at query+0x00. To hide New York, substitute a clone of that filter whose body-level isCollisionEnabled only accepts Gotham bodies. This needs the hknpCollisionFilter vtable slot (8 methods; group filter vtable exe+5287660).

2b implementation (built 2026-10-01, not yet run)

  • src/sm_guest/havok.h: addresses and layouts above. src/sm_guest/gotham.h: hull loading, shape and batch building, the shape-pointer set, and the slot-6 query-filter detour with hknpBody shape-offset self-calibration.
  • Hooks:
    • frame update exe+16244c0: main thread; Pump builds 64 shapes per frame and runs dev commands
    • hknpWorld::castRay: patches the query filter's vtable once
  • Commands (logs/sm_cmd.txt):
    • gotham load <file> [limit] [yoff]: the file's origin goes to the hero's feet
    • gotham filter on|off
    • gotham status
    • gotham perframe N
    • mem, ptr
  • tools/obj_to_gotham.py: converts an AK export into a hull file (guest m, Y up, relative to Batman's feet). Near-flat hulls are thickened by 10 cm because Havok's hull builder rejects flat sets.
  • logs/gotham_150m.bin: 42,237 hulls from the first export (3,181 thickened).

First test plan

  1. gotham status
  2. gotham load gotham_150m.bin 50: 50 nearest hulls, a single batch
  3. Check the log: system added, body count, no crash
  4. gotham filter on: the hero should stand on the Gotham roof only
  5. Scale up (2000, then everything), watching for a body-capacity limit