perf(apply): stutter is NOT the game thread -- and the flat floor cannot be relaxed

Two things the owner reported from playing 412a7ad. One is answered, one is a null result that Codex flagged itself rather than dressing up. THE FLATTENED TUNNEL FLOORS -- capability-safe, and worth almost nothing He has now flagged these twice: every tunnel carries a smooth flat strip running in and out through otherwise craggy rock. The idea was to make the floor CONDITIONAL -- assert it only where the natural rock fails walkability, leave the rock alone elsewhere. Cheaper and better looking, in theory. The floor is now skipped only when the exact no-floor field passes the same player-fit validator at foot offsets 0, -1, +1. Unknown or failed keeps the slab. natural-floor skips accepted 1,539 of 1,529,241 tests = 0.10% player-fit cells 20,153 -> 20,153 reachable cells 10,483 -> 10,483 arrival -> departure connected, both dihedral p50/p90 2.5429 / 33.8499 deg, IDENTICAL mesh time (their batch) 1.757135 -> 1.757140 s Capability preserved exactly. Visual complaint NOT solved, and no speed gained. ⭐ The useful part is what it PROVED by trying to go further. Every broader policy lost walkable space: analytic-only fit -217, reachable -195 tightened analytic fit -76, reachable -76 exact +/-4 foot fit -16, reachable -16 ⇒ The floor cannot be relaxed without changing the walkability contract or adding a route-aware global proof. That is a real constraint, now measured rather than assumed. Codex's own words, and it was right to lead with them: "the conservative floor change is capability-safe, but it does not visibly solve the flattened-strip complaint." THE STUTTER -- measured, and it is not where we thought Game-thread apply, meshed tiles, under -nullrhi: total apply p50 0.107 ms p95 0.153 ms max 0.273 ms stream upload/RMC p50 0.040 p95 0.088 max 0.124 component creation p50 0.019 p95 0.021 max 0.035 registration p50 0.010 p95 0.011 max 0.020 collision config p50 0.005 p95 0.007 max 0.019 A quarter of a millisecond at worst. The game-thread drain is NOT the hitch. ⇒ Remaining visible stutter is most likely render-thread/RHI work or asynchronous collision cooking behind RealtimeMeshComponent, which is off-limits for edits. Added anyway as a cheap safety valve: MaxMeshApplyMilliseconds, default 2 ms of drain budget per frame. Over 729 apply frames: drain p50/p95/max 0.111/0.182/0.313 ms, budget hits 0, at most 2 visible applies in a frame. It costs nothing today and caps a future burst. Request-to-ready, now timed after game-thread application: all p50 57.1 ms p95 432.9 ms max 919.4 ms -> 2.60 m at 6 m/s meshed p50 134.1 ms p95 457.4 ms max 919.4 ms ⚠️ My own verification: 1.197 / 1.131 / 1.118 s vs 1.088-1.102 s on 412a7ad. Mean +4.7% -- below the 17% noise floor, but slower in all three runs, and the validator runs 1.5M times to accept 1,539 skips. Geometry moved by 4 triangles (153,740 -> 153,744), which is allowed. If the next round cannot make that validator earn its place, it should come out. Build 0 errors. Peak RSS 1.67 GB export / 1.90 GB game. Nothing outside Plugins/VoxelForge; RealtimeMeshComponent untouched. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_012aheo2crrZmHuYtPpdY2Cb
2026-09-10 14:46:29 +02:00
1 parent 412a7ad219
commit 383ec86c37
@@ -3591,8 +3591,10 @@ namespace
    {
    public:
        FRoomGraphSource(const FStrateGenerationParams& InP, int32 InSeed,
-                         const UVoxelStrateManager* InManager)
+                         const UVoxelStrateManager* InManager,
+                         const UVoxelGenerator* InGenerator = nullptr)
            : P(InP), Seed(InSeed), SeedU((uint32)InSeed), Manager(InManager)
+            , Generator(InGenerator)
            , ManagerLifetimeId(InManager ? InManager->GetCacheLifetimeId() : 0)
            , ParamsFingerprint(FCrc::MemCrc32(&InP, sizeof(InP)))
        {}
@@ -3791,6 +3793,37 @@ namespace
            return P.RoomDensity > 0.0f && P.RoomSpacing > 0.0f;
        }

+        void BuildSupportColumn(
+            float WorldX, float WorldY,
+            const FChunkSDFCache& Cache,
+            FTunnelSupportFloorColumn& OutColumn) const
+        {
+            if (Generator == nullptr)
+            {
+                VoxelCaveMorphology::BuildTunnelSupportFloorColumn(
+                    WorldX, WorldY, Cache, OutColumn);
+                return;
+            }
+
+            // This is a synchronous, non-owning view of the exact field with only the graph
+            // support slab disabled. BuildTunnelSupportFloorColumn consumes it immediately and
+            // retains only the proven interval decision in the worker-local column cache.
+            const auto SampleWithoutTunnelSupportFloor =
+                [this](float X, float Y, float Z) -> float
+            {
+                return Generator->GetDensityWithParams(
+                    X, Y, Z, P, ParamsFingerprint, LayoutVersion,
+                    /*bApplyLegacyStructuralPosts=*/true,
+                    /*bApplyTunnelSupportFloor=*/false);
+            };
+            FTunnelSupportFloorDensitySampler NaturalSampler =
+                SampleWithoutTunnelSupportFloor;
+            VoxelCaveMorphology::BuildTunnelSupportFloorColumn(
+                WorldX, WorldY, Cache, OutColumn, &NaturalSampler,
+                P.StrateTopWorldZ, P.StrateBottomWorldZ,
+                P.BoundarySealThickness);
+        }
+
        const FTunnelSupportFloorColumn* GetSupportColumn(const FVector& Position) const
        {
            FState& S = State();
@@ -3809,7 +3842,7 @@ namespace
                    IX, IY, &Cache, S.SupportColumns.Clock, bNewColumn);
                if (bNewColumn)
                {
-                    VoxelCaveMorphology::BuildTunnelSupportFloorColumn(
+                    BuildSupportColumn(
                        static_cast<float>(Position.X),
                        static_cast<float>(Position.Y),
                        Cache,
@@ -3818,7 +3851,7 @@ namespace
                return Column;
            }

-            VoxelCaveMorphology::BuildTunnelSupportFloorColumn(
+            BuildSupportColumn(
                static_cast<float>(Position.X), static_cast<float>(Position.Y),
                GetCache(), S.FractionalSupportColumn);
            return &S.FractionalSupportColumn;
@@ -6633,6 +6666,7 @@ namespace
        int32  Seed;
        uint32 SeedU;
        TWeakObjectPtr<const UVoxelStrateManager> Manager;
+        const UVoxelGenerator* Generator = nullptr;
        uint64 ManagerLifetimeId = 0;
        uint32 ParamsFingerprint;
        uint32 LayoutVersion = 0;
@@ -9408,7 +9442,8 @@ namespace VoxelDensityOps

    void BuildTunnelNetworkStack(FVoxelOpStack& OutStack, const FStrateGenerationParams& P,
                                 int32 Seed, float SpineRadius, const UVoxelStrateManager* StrateManager,
-                                 bool bAppendStructuralPosts)
+                                 bool bAppendStructuralPosts,
+                                 const UVoxelGenerator* Generator)
    {
        // ⚠️ ÉTAPES A + B + C1 — LA PILE EST COMPLÈTE POUR CET ARCHÉTYPE.
        // Portés : échelle verticale, roc de base, warp, graphe de salles (+ pits + cheminées),
@@ -9452,7 +9487,8 @@ namespace VoxelDensityOps

        // La source de salles est retenue par pointeur non possédant : les terrasses re-interrogent
        // son cache SDF en Z±1. Même motif que `FShaftFieldSource` → `FShaftLedgeMod`.
-        TUniquePtr<FRoomGraphSource> RoomSource = MakeUnique<FRoomGraphSource>(P, Seed, StrateManager);
+        TUniquePtr<FRoomGraphSource> RoomSource = MakeUnique<FRoomGraphSource>(
+            P, Seed, StrateManager, Generator);
        const FRoomGraphSource* RoomPtr = RoomSource.Get();

        OutStack.Add(MakeConstantRockSource(P.BaseDensity));