From 1f11ba9b38118a5743c021f0df7c21b3a25991ef Mon Sep 17 00:00:00 2001
From: Erik <erik.nihlen@gmail.com>
Date: Tue, 19 May 2026 16:04:45 +0200
Subject: [PATCH] =?UTF-8?q?feat(diag):=20Cluster=20A=20=E2=80=94=20extend?=
 =?UTF-8?q?=20[cell-cache]=20with=20AABB=20+=20bsphere=20+=20recursive=20p?=
 =?UTF-8?q?oly=20count?=
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The original Phase E [cell-cache] probe (fda6af7) only showed the BSP root
node's direct poly count, which was always 0 for non-trivial trees (internal
node root). Extending the probe to:

- Recursively walk the BSP tree and count total leaf polys
- Detect unmatched poly IDs (BSP leaves referencing IDs not in our resolved dict)
- Dump the BSP root bounding sphere (center + radius)
- Dump the cell's local AABB (min/max from poly vertices)
- Dump the cell's world origin (cellTransform * (0,0,0))

The extended data made the route-δ diagnosis definitive: Holtburg cells DO
have full physics polygons in their BSPs (e.g. 0xA9B40143 has 14 polys all
resolved, full Z range 0-2.8 m). The bug is upstream — AABB-based cell
containment is too tight to capture a standing player at most thresholds
between rooms, so the indoor cell-BSP branch fires only intermittently.

Retail uses portal traversal (CObjMaint::HandleObjectEnterCell + cell-side
portal data) which propagates CellId at door crossings. Our AABB-containment
shortcut is partial. This diagnostic stays in place as infrastructure for
the follow-up "Indoor portal-based cell tracking" phase.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
---
 src/AcDream.Core/Physics/PhysicsDataCache.cs | 42 +++++++++++++++++++-
 1 file changed, 41 insertions(+), 1 deletion(-)

diff --git a/src/AcDream.Core/Physics/PhysicsDataCache.cs b/src/AcDream.Core/Physics/PhysicsDataCache.cs
index 6fd45a4..291aabf 100644
--- a/src/AcDream.Core/Physics/PhysicsDataCache.cs
+++ b/src/AcDream.Core/Physics/PhysicsDataCache.cs
@@ -174,8 +174,48 @@ public sealed class PhysicsDataCache
             var root = cellStruct.PhysicsBSP?.Root;
             int bspRootPolyCount   = root?.Polygons?.Count ?? 0;
             bool bspRootHasChildren = root?.PosNode is not null || root?.NegNode is not null;
+
+            // Recursive walk: count total leaf poly references + how many of
+            // those poly IDs are absent from the resolved dict. If
+            // bspTotalLeafPolys == 0 the BSP has no collidable polys at all.
+            // If bspUnmatchedIds > 0 the BSP references IDs we didn't resolve
+            // (data-deserialization quirk hypothesis).
+            int bspTotalLeafPolys = 0;
+            int bspUnmatchedIds   = 0;
+            if (root is not null)
+            {
+                var stack = new System.Collections.Generic.Stack<DatReaderWriter.Types.PhysicsBSPNode>();
+                stack.Push(root);
+                while (stack.Count > 0)
+                {
+                    var n = stack.Pop();
+                    if (n.Polygons is not null)
+                    {
+                        foreach (var pid in n.Polygons)
+                        {
+                            bspTotalLeafPolys++;
+                            if (!resolved.ContainsKey(pid)) bspUnmatchedIds++;
+                        }
+                    }
+                    if (n.PosNode is not null) stack.Push(n.PosNode);
+                    if (n.NegNode is not null) stack.Push(n.NegNode);
+                }
+            }
+
+            var bs = root?.BoundingSphere;
+            string bsStr = bs is null
+                ? "bsphere=n/a"
+                : System.FormattableString.Invariant(
+                    $"bsphere=({bs.Origin.X:F2},{bs.Origin.Y:F2},{bs.Origin.Z:F2}) r={bs.Radius:F2}");
+
+            // World origin = cellTransform * (0,0,0,1). Tells us where this cell
+            // sits in world coordinates, so we can cross-check whether the
+            // player's worldPos actually lies inside the AABB when transformed
+            // back to local.
+            var worldOrigin = Vector3.Transform(Vector3.Zero, worldTransform);
+
             Console.WriteLine(System.FormattableString.Invariant(
-                $"[cell-cache] envCellId=0x{envCellId:X8} physicsPolyCount={cellStruct.PhysicsPolygons?.Count ?? 0} resolvedCount={resolved.Count} bspRootPolyCount={bspRootPolyCount} bspRootHasChildren={bspRootHasChildren}"));
+                $"[cell-cache] envCellId=0x{envCellId:X8} physicsPolyCount={cellStruct.PhysicsPolygons?.Count ?? 0} resolvedCount={resolved.Count} bspTotalLeafPolys={bspTotalLeafPolys} bspUnmatchedIds={bspUnmatchedIds} {bsStr} aabbMin=({aabbMin.X:F2},{aabbMin.Y:F2},{aabbMin.Z:F2}) aabbMax=({aabbMax.X:F2},{aabbMax.Y:F2},{aabbMax.Z:F2}) worldOrigin=({worldOrigin.X:F2},{worldOrigin.Y:F2},{worldOrigin.Z:F2})"));
         }
     }