fix(render): Phase A8 — pool aliasing in EnvCellRenderer (visual chaos root cause)
The post-Wave-5 indoor branch chaos (flickering, missing walls, GPU 100%, ~10 FPS) is caused by two interconnected pool-management bugs in EnvCellRenderer that line-by-line WB comparison surfaced in 30 minutes. Neither was found by the five post-Wave-5 speculative fixes because none of them inspected the pool path. Bug #1 — GetPooledList missing list.Clear(): The reuse branch returned pool lists with prior-frame data still inside. PrepareRenderBatches' merge phase pattern `gfxDict[k] = list; list.AddRange(...)` assumes empty lists. Without Clear(), lists grow unbounded each frame, GPU draws cumulative instance counts, and per-instance transforms become a stew of past + present data. Mirrors WB ObjectRenderManagerBase.cs:1221-1233. Bug #2 — Render uses snapshot.BatchedByCell.Count instead of PostPreparePoolIndex: The snapshot author dropped WB's PostPreparePoolIndex field calling it "scenery-only," then "compensated" in Render by setting _poolIndex to the cell count. The cell count has no relation to the pool — Prepare may have used 50+ pool lists for an 18-cell scene. Render's filter-path GetPooledList then returns lists that ARE in snapshot.BatchedByCell, corrupting the snapshot mid-Render. Restoring PostPreparePoolIndex (WB VisibilitySnapshot.cs:31) correctly places Render's pool cursor past the snapshot's owned region. Bug #3 (minor) — PopulateRecursive hardcoded isSetup:false for nested parts: Setup IDs use high-byte 0x02 (per retail). WB ObjectRenderManagerBase.cs:813 checks `(partId >> 24) == 0x02` to detect nested Setups. Our port always passed isSetup:false, silently dropping any nested Setup (its TryGetRenderData returns IsSetup=true, Render's `!IsSetup` guard skips the draw). Probably rare in EnvCells but fixed for completeness. Regression coverage: - GetPooledList_ReusedList_IsClearedBeforeReturn — would have failed pre-fix - GetPooledList_FreshList_IsAlwaysEmpty — sanity check - Snapshot_PostPreparePoolIndex_IsInitSettable — compile-time guarantee - Snapshot_PostPreparePoolIndex_DefaultsToZero — defensive default 86/86 App tests pass. Build green. The fix is the audit's primary deliverable; the GL state probe option-1 apparatus follows in a separate commit as defense-in-depth for any unidentified residual issue. Full audit + WB cross-reference in docs/research/2026-05-28-a8-env-cell-renderer-audit-findings.md. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
Erik
parent
3d0ffaa794
commit
9559726960
4 changed files with 408 additions and 9 deletions
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@ -352,10 +352,18 @@ public sealed unsafe class EnvCellRenderer : IDisposable
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foreach (var (partId, partTransform) in rd.SetupParts)
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{
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// Each Setup part is a GfxObj — not a nested Setup.
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// Compose: world = partTransform (relative to setup) * setup world transform.
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//
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// FIX 2026-05-28: detect nested Setups via the high-byte
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// 0x02 convention (Setup IDs start with 0x02; plain GfxObj
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// IDs start with 0x01). Mirrors WB
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// ObjectRenderManagerBase.cs:813. Original port hardcoded
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// isSetup:false which silently dropped any nested Setup —
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// its TryGetRenderData returns IsSetup=true, and Render's
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// `if (!renderData.IsSetup)` guard then skips the draw.
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var combined = partTransform * transform;
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PopulateRecursive(group, partId, isSetup: false, combined, cellId);
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bool partIsSetup = (partId >> 24) == 0x02UL;
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PopulateRecursive(group, partId, partIsSetup, combined, cellId);
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}
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}
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else
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@ -518,12 +526,21 @@ public sealed unsafe class EnvCellRenderer : IDisposable
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}
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// WB EnvCellRenderManager.cs:361-372: atomic swap under _renderLock.
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//
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// FIX 2026-05-28 (pool aliasing root cause): capture _poolIndex's
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// high-water mark from the merge phase into the snapshot's
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// PostPreparePoolIndex BEFORE the reset to 0. Render reads it back
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// to set its pool cursor past the snapshot's owned lists. Without
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// this capture, Render's filter-path GetPooledList returns lists
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// the snapshot is still referencing, corrupting per-frame instance
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// data. See docs/research/2026-05-28-a8-env-cell-renderer-audit-findings.md.
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lock (_renderLock)
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{
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_activeSnapshot = new EnvCellVisibilitySnapshot
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{
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BatchedByCell = newBatchedByCell,
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VisibleLandblocks = landblocks,
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BatchedByCell = newBatchedByCell,
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VisibleLandblocks = landblocks,
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PostPreparePoolIndex = _poolIndex,
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// VisibleGroups / VisibleGfxObjIds are stored as extra fields below.
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};
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// Stash the global groups on the snapshot for use in the unfiltered render path.
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@ -611,7 +628,15 @@ public sealed unsafe class EnvCellRenderer : IDisposable
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var snapshot = _activeSnapshot;
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// WB EnvCellRenderManager.cs:403-404:
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_shader.Use();
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_poolIndex = snapshot.BatchedByCell.Count; // reset point (mirrors WB line 405)
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// FIX 2026-05-28 (pool aliasing root cause): mirror WB
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// EnvCellRenderManager.cs:405 — restore the pool cursor to the
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// high-water mark Prepare's merge phase reached, so any
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// GetPooledList calls below return lists past the snapshot's
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// owned region. Original code used `snapshot.BatchedByCell.Count`
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// (number of cells, e.g. 18) which has no relation to the pool
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// index and pointed back into snapshot data, corrupting it
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// mid-Render. See docs/research/2026-05-28-a8-env-cell-renderer-audit-findings.md.
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_poolIndex = snapshot.PostPreparePoolIndex;
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// FIX 2026-05-28: invalidate static GL-state caches at start of Render.
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// Mirrors WB EnvCellRenderManager.cs:404-410:
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@ -958,9 +983,22 @@ public sealed unsafe class EnvCellRenderer : IDisposable
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private List<InstanceData> GetPooledList()
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{
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// Mirrors WB ObjectRenderManagerBase.cs:1221-1233 — the reuse
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// branch MUST clear the list before returning. PrepareRenderBatches'
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// merge phase pattern is `gfxDict[k] = list; list.AddRange(...)`,
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// which assumes the list is empty. Without the clear, lists grow
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// unbounded across frames and each frame's draw includes all prior
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// frames' stale data. Original port omitted the Clear() call — root
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// cause of post-Wave-5 visual chaos (FIX 2026-05-28). See
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// docs/research/2026-05-28-a8-env-cell-renderer-audit-findings.md.
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lock (_listPool)
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{
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if (_poolIndex < _listPool.Count) return _listPool[_poolIndex++];
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if (_poolIndex < _listPool.Count)
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{
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var list = _listPool[_poolIndex++];
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list.Clear();
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return list;
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}
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var fresh = new List<InstanceData>();
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_listPool.Add(fresh);
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_poolIndex++;
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@ -7,9 +7,9 @@ namespace AcDream.App.Rendering.Wb;
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/// WB's <c>VisibilitySnapshot</c> at
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/// <c>references/WorldBuilder/Chorizite.OpenGLSDLBackend/Lib/VisibilitySnapshot.cs:1-36</c>,
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/// narrowed to the fields <see cref="EnvCellRenderer"/> actually consumes
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/// (<c>BatchedByCell</c> + <c>VisibleLandblocks</c>). The scenery-side
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/// <c>VisibleGroups</c> / <c>VisibleGfxObjIds</c> / <c>IntersectingLandblocks</c>
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/// / <c>PostPreparePoolIndex</c> are dropped — we render scenery through
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/// (<c>BatchedByCell</c> + <c>VisibleLandblocks</c> + <c>PostPreparePoolIndex</c>).
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/// The scenery-side <c>VisibleGroups</c> / <c>VisibleGfxObjIds</c> /
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/// <c>IntersectingLandblocks</c> are dropped — we render scenery through
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/// <see cref="WbDrawDispatcher"/>, not through this snapshot.
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///
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/// <para>Used as an immutable snapshot atomically swapped under the
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@ -30,6 +30,19 @@ public sealed class EnvCellVisibilitySnapshot
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/// </summary>
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public Dictionary<uint, Dictionary<ulong, List<InstanceData>>> BatchedByCell { get; init; } = new();
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/// <summary>
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/// Pool-index high-water mark after PrepareRenderBatches' merge phase.
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/// Mirrors WB <c>VisibilitySnapshot.PostPreparePoolIndex</c> at
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/// <c>references/WorldBuilder/.../VisibilitySnapshot.cs:31</c>.
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/// <para>Read by <see cref="EnvCellRenderer.Render"/> to set the pool
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/// cursor to a safe region past the snapshot's owned lists, so any
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/// <c>GetPooledList</c> calls inside Render don't trample data the
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/// snapshot still references. Dropping this field caused the post-Wave-5
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/// visual chaos — see
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/// <c>docs/research/2026-05-28-a8-env-cell-renderer-audit-findings.md</c>.</para>
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/// </summary>
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public int PostPreparePoolIndex { get; init; }
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/// <summary>True when no visible cells were produced this prepare cycle.</summary>
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public bool IsEmpty => VisibleLandblocks.Count == 0 && BatchedByCell.Count == 0;
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}
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