feat(rendering): pack scene dispatcher inputs

Capture immutable presentation payloads in the render scene, flatten unique entity and mesh-part records into the borrowed frame arena, and compare every routed dispatcher input tuple without changing the production draw source.

src/AcDream.App/Rendering/Scene/RenderFrameProduct.cs

@@ -1,5 +1,6 @@
 using System.Numerics;
 using AcDream.Core.Selection;
+using AcDream.Core.World;
 
 namespace AcDream.App.Rendering.Scene;
 
@@ -36,6 +37,17 @@ internal readonly record struct RenderFrameTransformRecord(
     int PartIndex,
     Matrix4x4 LocalToWorld);
 
+internal readonly record struct RenderFrameEntityCandidate(
+    RenderProjectionRecord Projection,
+    int MeshPartOffset,
+    int MeshPartCount,
+    bool Animated);
+
+internal readonly record struct RenderFrameMeshPart(
+    RenderProjectionId ProjectionId,
+    int PartIndex,
+    MeshRef MeshRef);
+
 internal readonly record struct RenderFrameClassificationRecord(
     RenderProjectionId ProjectionId,
     int CandidateIndex,
@@ -77,7 +89,9 @@ internal readonly record struct RenderFrameDiagnosticCounts(
     int AlphaClassificationCount,
     int LightSetCount,
     int SelectionPartCount,
-    int RouteCandidateCount);
+    int RouteCandidateCount,
+    int EntityCandidateCount,
+    int MeshPartCount);
 
 /// <summary>
 /// A validated borrowed view over one reusable frame arena. Copies are safe:
@@ -133,6 +147,12 @@ internal readonly struct RenderFrameView
     public ReadOnlySpan<RenderFrameTransformRecord> Transforms =>
         Arena.Transforms;
 
+    public ReadOnlySpan<RenderFrameEntityCandidate> EntityCandidates =>
+        Arena.EntityCandidates;
+
+    public ReadOnlySpan<RenderFrameMeshPart> MeshParts =>
+        Arena.MeshParts;
+
     public ReadOnlySpan<RenderFrameClassificationRecord> Classifications =>
         Arena.Classifications;
 
@@ -192,6 +212,8 @@ internal sealed class RenderFrameArena
     private RenderFrameCellRange[] _cellRanges = [];
     private RenderProjectionRecord[] _dynamics = [];
     private RenderFrameTransformRecord[] _transforms = [];
+    private RenderFrameEntityCandidate[] _entityCandidates = [];
+    private RenderFrameMeshPart[] _meshParts = [];
     private RenderFrameClassificationRecord[] _classifications = [];
     private RenderFrameObjectLightSet[] _lightSets = [];
     private RenderFrameSelectionPart[] _selectionParts = [];
@@ -202,6 +224,8 @@ internal sealed class RenderFrameArena
     private int _cellRangeCount;
     private int _dynamicCount;
     private int _transformCount;
+    private int _entityCandidateCount;
+    private int _meshPartCount;
     private int _classificationCount;
     private int _lightSetCount;
     private int _selectionPartCount;
@@ -234,7 +258,9 @@ internal sealed class RenderFrameArena
             _alphaClassificationCount,
             _lightSetCount,
             _selectionPartCount,
-            _routeCandidateCount);
+            _routeCandidateCount,
+            _entityCandidateCount,
+            _meshPartCount);
 
     internal ReadOnlySpan<RenderProjectionRecord> OutdoorStaticCandidates =>
         _outdoor.AsSpan(0, _outdoorCount);
@@ -251,6 +277,12 @@ internal sealed class RenderFrameArena
     internal ReadOnlySpan<RenderFrameTransformRecord> Transforms =>
         _transforms.AsSpan(0, _transformCount);
 
+    internal ReadOnlySpan<RenderFrameEntityCandidate> EntityCandidates =>
+        _entityCandidates.AsSpan(0, _entityCandidateCount);
+
+    internal ReadOnlySpan<RenderFrameMeshPart> MeshParts =>
+        _meshParts.AsSpan(0, _meshPartCount);
+
     internal ReadOnlySpan<RenderFrameClassificationRecord> Classifications =>
         _classifications.AsSpan(0, _classificationCount);
 
@@ -284,6 +316,8 @@ internal sealed class RenderFrameArena
         _cellRangeCount = 0;
         _dynamicCount = 0;
         _transformCount = 0;
+        _entityCandidateCount = 0;
+        _meshPartCount = 0;
         _classificationCount = 0;
         _lightSetCount = 0;
         _selectionPartCount = 0;
@@ -397,6 +431,46 @@ internal sealed class RenderFrameArena
         _transforms[_transformCount++] = transform;
     }
 
+    internal void AddEntityCandidate(
+        ulong epoch,
+        in RenderProjectionRecord projection,
+        bool animated)
+    {
+        EnsureBuilding(epoch);
+        IReadOnlyList<MeshRef>? meshRefs =
+            projection.EntityPayload.MeshRefs;
+        int meshPartCount = meshRefs?.Count ?? 0;
+        if (meshPartCount != projection.MeshSet.MeshCount)
+        {
+            throw new InvalidOperationException(
+                $"Projection {projection.Id} declares "
+                + $"{projection.MeshSet.MeshCount} mesh parts but its "
+                + $"presentation payload contains {meshPartCount}.");
+        }
+
+        int meshPartOffset = _meshPartCount;
+        EnsureCapacity(
+            ref _meshParts,
+            checked(meshPartOffset + meshPartCount));
+        for (int partIndex = 0; partIndex < meshPartCount; partIndex++)
+        {
+            _meshParts[_meshPartCount++] = new RenderFrameMeshPart(
+                projection.Id,
+                partIndex,
+                meshRefs![partIndex]);
+        }
+
+        EnsureCapacity(
+            ref _entityCandidates,
+            _entityCandidateCount + 1);
+        _entityCandidates[_entityCandidateCount++] =
+            new RenderFrameEntityCandidate(
+                projection,
+                meshPartOffset,
+                meshPartCount,
+                animated);
+    }
+
     internal void AddClassification(
         ulong epoch,
         in RenderFrameClassificationRecord classification)
@@ -529,6 +603,10 @@ internal sealed class RenderFrameArena
     {
         if (_selectionPartCount > 0)
             Array.Clear(_selectionParts, 0, _selectionPartCount);
+        if (_entityCandidateCount > 0)
+            Array.Clear(_entityCandidates, 0, _entityCandidateCount);
+        if (_meshPartCount > 0)
+            Array.Clear(_meshParts, 0, _meshPartCount);
     }
 
     private static void EnsureCapacity<T>(ref T[] values, int required)
@@ -603,6 +681,11 @@ internal readonly struct RenderFrameWriter
     public void AddTransform(in RenderFrameTransformRecord transform) =>
         Arena.AddTransform(_epoch, in transform);
 
+    public void AddEntityCandidate(
+        in RenderProjectionRecord projection,
+        bool animated) =>
+        Arena.AddEntityCandidate(_epoch, in projection, animated);
+
     public void AddClassification(
         in RenderFrameClassificationRecord classification) =>
         Arena.AddClassification(_epoch, in classification);