erik/acdream
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions 1

fix(#185): landblock collision part-id uint32 overflow dropped stair steps

Browse source 
Root cause (live capture #3 + code): GameWindow's per-part landblock shadow
registration used a synthetic part-id `entity.Id * 256u + partIndex` that
OVERFLOWS uint32 for class-prefixed landblock ids (0x40/0x80/0xC0...). The << 8
drops the prefix byte, so different-class entities sharing the low 24 bits
collide on ONE shadow part-id and Register's deregister-then-insert silently
overwrites one entity's collision geometry. Landblock 0xF682 had 23 such
collisions incl. the stair runs (0xF6822100 <- {0x40F68221, 0xC0F68221}, ...),
so 3 mid-staircase steps rendered but had no collision -> the player floats into
the hole and the (faithful) PrecipiceSlide wedge fires = the 'invisible wall
half-way up the stairs'.

Fix (Option A, retail-faithful): register each multi-part landblock entity via
ShadowObjectRegistry.RegisterMultiPart under its UNIQUE 32-bit entity.Id
(retail CPhysicsObj::add_shadows_to_cells 0x00514ae0 -> CPartArray::AddPartsShadow
- one object, a part array; no synthetic per-part id). New testable builder
ShadowShapeBuilder.FromLandblockBspParts decomposes each MeshRef.PartTransform to
local pos/rot/scale; RegisterMultiPart reconstructs the identical world placement.
Building shells stay excluded (building channel); the Setup cyl/sphere path is
unchanged (runs only when entityBsp==0, retail BSP-xor-cyl dispatch). Despawn is
landblock-scoped (RemoveLandblock by cell prefix), so the id change is safe.

Tests: ShadowRegistrationOverflowTests (overflow arithmetic; old scheme drops one;
RegisterMultiPart keeps both; builder). Issue185OutdoorStairsSeamReplayTests
(dat-free clean-climb pin). Core 2629 / App 741 green, 0 warnings.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
Erik 2026-07-08 10:07:50 +02:00
parent b62b13ce21
commit 07c5b832cf
6 changed files with 897 additions and 67 deletions
Download patch file Download diff file Expand all files Collapse all files

99
src/AcDream.App/Rendering/GameWindow.cs
View file

@ -7896,77 +7896,42 @@ public sealed class GameWindow : IDisposable
// docs/superpowers/specs/2026-05-21-cylinder-fallback-dedup-design.md.
bool _isLandblockStab = (entity.Id & 0xFF000000u) == 0xC0000000u;
if (_isScenery) scTried++;
// Register EACH physics-enabled part so multi-part Setups
// (buildings, trees) have all their collision geometry registered.
// Each part gets its own ShadowEntry with its world-space transform.
var entityRoot =
System.Numerics.Matrix4x4.CreateFromQuaternion(entity.Rotation) *
System.Numerics.Matrix4x4.CreateTranslation(entity.Position);
uint partIndex = 0;
foreach (var meshRef in entity.MeshRefs)
// #185 FIX (2026-07-08): register the entity's BSP parts as ONE
// multi-part shadow object keyed on the entity's UNIQUE 32-bit id,
// via RegisterMultiPart (retail CPhysicsObj::add_shadows_to_cells
// 0x00514ae0 → CPartArray::AddPartsShadow — one object, a part array).
//
// The former per-part Register(entity.Id * 256u + partIndex) OVERFLOWED
// uint32 for class-prefixed landblock ids (0x40/0x80/0xC0…): the << 8
// dropped the prefix byte, so different-class entities sharing the low
// 24 bits collided on ONE shadow part-id and Register's
// deregister-then-insert silently overwrote one entity's collision
// geometry — the #185 "invisible wall half-way up the stairs" (rendered
// steps with no collision; 23 such part-id collisions in landblock
// 0xF682 alone: 0xF6822100 ← {0x40F68221, 0xC0F68221}, …). entity.Id is
// unique, so RegisterMultiPart has no synthetic id and no collision.
// Building shells stay excluded (they collide via the per-LandCell
// building channel, CSortCell::find_collisions). The Setup CylSphere/
// Sphere path below is UNCHANGED and only runs when entityBsp == 0
// (retail binary dispatch: BSP xor cyl). Builder:
// ShadowShapeBuilder.FromLandblockBspParts.
var bspShapes = AcDream.Core.Physics.ShadowShapeBuilder.FromLandblockBspParts(
entity.MeshRefs, entity.IsBuildingShell,
id => _physicsDataCache.GetGfxObj(id));
entityBsp = bspShapes.Count;
if (entityBsp > 0)
{
// BR-7 / A6.P4 (2026-06-11): building SHELLS are not shadow
// objects in retail — their collision is the per-LandCell
// building channel (CSortCell::find_collisions, Ghidra
// 0x005340a0, dispatched off the CacheBuilding entry at the
// building's origin landcell). Registering them here is what
// put the cottage GfxObj into the radial sweep's reach from
// the cellar (#98). Interior statics + outdoor stab objects
// (LandBlockInfo.Objects) remain shadow objects.
if (entity.IsBuildingShell) break;
var partCached = _physicsDataCache.GetGfxObj(meshRef.GfxObjId);
if (partCached?.BSP?.Root is null) { partIndex++; continue; }
// Compute the part's world-space position from its transform.
var partWorld = meshRef.PartTransform * entityRoot;
// Decompose to extract scale (scenery objects have it baked
// into PartTransform), rotation, and translation.
System.Numerics.Vector3 partScale3;
System.Numerics.Quaternion partRot;
System.Numerics.Vector3 partPos;
if (System.Numerics.Matrix4x4.Decompose(partWorld,
out partScale3, out partRot, out partPos))
{ /* decompose succeeded */ }
else
{
partScale3 = System.Numerics.Vector3.One;
partRot = entity.Rotation;
partPos = new System.Numerics.Vector3(partWorld.M41, partWorld.M42, partWorld.M43);
}
// Use uniform scale (X component) — AC objects are uniformly scaled.
float partScale = partScale3.X;
if (partScale <= 0f) partScale = 1f;
// Local bounding sphere radius × world scale = world-space radius
// for the broad phase. The BSPQuery will also use `partScale` to
// transform player spheres into the unscaled BSP coordinate space.
float localRadius = partCached.BoundingSphere?.Radius ?? 1f;
float worldRadius = localRadius * partScale;
// Use a unique sub-ID per part: entity.Id * 256 + partIndex.
uint partId = entity.Id * 256u + partIndex;
_physicsEngine.ShadowObjects.Register(
partId, meshRef.GfxObjId,
partPos, partRot, worldRadius,
_physicsEngine.ShadowObjects.RegisterMultiPart(
entity.Id, entity.Position, entity.Rotation, bspShapes,
0u, AcDream.Core.Physics.EntityCollisionFlags.None,
origin.X, origin.Y, lb.LandblockId,
AcDream.Core.Physics.ShadowCollisionType.BSP, 0f,
partScale,
seedCellId: entity.ParentCellId ?? 0u);
seedCellId: entity.ParentCellId ?? 0u, isStatic: true);
// L.2d slice 1 (2026-05-13): [entity-source] greppable from [resolve-bldg].
// partCached?.BSP?.Root non-null was checked above (else `continue`),
// so hasPhys=true on this path.
// state/flags literals: landblock-baked scenery has no server PhysicsState
// broadcast and no PWD bitfield; defaults match static-solid semantics.
// One line per BSP part, all under the entity's single id (no synthetic partId).
if (AcDream.Core.Physics.PhysicsDiagnostics.ProbeBuildingEnabled)
Console.WriteLine(System.FormattableString.Invariant(
$"[entity-source] id=0x{partId:X8} entityId=0x{entity.Id:X8} src=0x{entity.SourceGfxObjOrSetupId:X8} gfxObj=0x{meshRef.GfxObjId:X8} lb=0x{lb.LandblockId:X8} type=BSP note=partIdx={partIndex} hasPhys=true state=0x{0u:X8} flags={AcDream.Core.Physics.EntityCollisionFlags.None}"));
entityBsp++;
partIndex++;
for (int _pi = 0; _pi < bspShapes.Count; _pi++)
Console.WriteLine(System.FormattableString.Invariant(
$"[entity-source] id=0x{entity.Id:X8} entityId=0x{entity.Id:X8} src=0x{entity.SourceGfxObjOrSetupId:X8} gfxObj=0x{bspShapes[_pi].GfxObjId:X8} lb=0x{lb.LandblockId:X8} type=BSP note=multipart-part{_pi} hasPhys=true state=0x{0u:X8} flags={AcDream.Core.Physics.EntityCollisionFlags.None}"));
}
// Register collision shapes from the Setup (if this entity has one).