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fix(physics): #149 — collide BSP-less landblock statics via Setup cylsphere

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Town props placed as landblock stabs whose ONLY collision is a Setup
CylSphere/Sphere (no physics BSP) registered ZERO collision shapes and were
walk-through -- torches, braziers, lamp-posts, candle-stands, posts.

Root: the ISSUES #83 / A1.6 gate `!_isLandblockStab` skipped Setup
cyl/sphere registration for ALL landblock stabs, on the false assumption
"landblock stabs collide via BSP only (retail CBuildingObj)." That
over-broadened -- it also killed collision for BSP-less stabs.

Retail's CPhysicsObj::FindObjCollisions (@0x0050f050) uses binary dispatch:
the object's physics BSP if it HAS one (HAS_PHYSICS_BSP_PS 0x10000), ELSE its
CSetup CylSpheres/Spheres -- never both. Confirmed via live retail cdb on the
Holtburg torch (Setup 0x020005D8 at world (105.99,17.17)): FindObjCollisions
target num_cylsphere=1, cyl h=2.2 -- a cylsphere, exact-matching the dat
(cylSphere r=0.2 h=2.2); the StabList confirms stab[95]=0x020005D8 there.

Fix: gate the Setup cyl/sphere registration on `entityBsp == 0` instead of
stab-ness. Preserves #83's anti-doubling (stab WITH a BSP -> BSP-only) while
restoring collision for BSP-less stabs. Other landblock entities on this path
(scenery -- tree-trunk cylspheres) are unaffected.

Live-verified: torch + candle/brazier family block now; ~115 cyl/sphere
Setups register across streamed landblocks. Core suite green (1595/0).

The earlier selection-sphere hypothesis was WRONG and is reverted -- the cdb's
r=0.48 sphere was the player/NPC body (every body sphere is ~0.48), not the
torch. The correct cdb method: capture the TARGET at FindObjCollisions (not
`this` in CSphere::intersects_sphere) and confirm by position + Setup-id.

(Issue numbered #149 to stay clear of main's #148; this worktree branched
before main's #145-148 were added.)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This commit is contained in:
Erik 2026-06-25 10:15:34 +02:00
parent 989cc25d80
commit 2ac7ea776f
2 changed files with 46 additions and 12 deletions
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36
src/AcDream.App/Rendering/GameWindow.cs
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@ -3830,7 +3830,8 @@ public sealed class GameWindow : IDisposable
CylHeight: (setup.Height > 0 ? setup.Height : setup.Radius * 2f) * entScale));
}
if (shapes.Count == 0) return;
if (shapes.Count == 0)
return;
// Decode PvP / Player / Impenetrable from PWD._bitfield.
// IsCreature comes from the spawn's ItemType (server-known type).
@ -7265,17 +7266,28 @@ public sealed class GameWindow : IDisposable
// clobber entries via Deregister.
{
var setup = _physicsDataCache.GetSetup(entity.SourceGfxObjOrSetupId);
// ISSUES #83 / Phase A1.6 (2026-05-21): landblock stabs use BSP
// collision exclusively (retail CBuildingObj). Skip Setup-derived
// CylSphere/Sphere/Radius shadow registrations for stabs to
// prevent the same doubled-collision bug A1 fixed for the
// mesh-AABB-fallback — but on the Setup path instead. Without
// this gate, a stab whose source is 0x02xxxxxx (Setup) with
// defined CylSpheres registers BOTH per-part BSP shadows AND a
// CylSphere shadow with id = entity.Id, producing an invisible
// collision cylinder at the stab origin alongside the correct
// BSP walls.
if (setup is not null && !_isLandblockStab)
// Retail binary collision dispatch (CPhysicsObj::FindObjCollisions
// @0x0050f050, see feedback_retail_binary_dispatch): an object uses
// its physics BSP if it HAS one (HAS_PHYSICS_BSP_PS 0x10000), ELSE
// its CSetup CylSpheres/Spheres — never both. The per-part BSP loop
// above already registered every BSP-bearing part (entityBsp counts
// them). So register the Setup's CylSpheres/Spheres ONLY when no BSP
// claimed this object (entityBsp == 0).
//
// This supersedes the ISSUES #83 / A1.6 (2026-05-21) gate that
// skipped Setup cyl/sphere for ALL landblock stabs to stop a
// BSP+cylinder doubled-collision. That gate over-broadened: it also
// killed collision for BSP-LESS stabs whose ONLY shape is a Setup
// CylSphere — e.g. the Holtburg town torch (stab Setup 0x020005D8,
// part 0x01001774 HasPhysics=False/BSP=null, cylSphere r=0.2 h=2.2).
// Retail collides with it via that cylsphere (live cdb 2026-06-25:
// FindObjCollisions target ncyl=1, cyl h=2.2 at world (105.99,17.17));
// acdream walked straight through. Gating on entityBsp==0 keeps #83's
// anti-doubling (stab WITH a BSP → BSP-only) while restoring cyl
// collision for BSP-less stabs. Other landblock entities on this path
// (scenery — tree-trunk cylspheres etc.) are unaffected: with no BSP
// they still register cyl/sphere exactly as before.
if (setup is not null && entityBsp == 0)
{
float entScale = entity.Scale > 0f ? entity.Scale : 1f;
uint shapeIndex = 0;