Reapply "perf(rendering): draw retained frame product"

This reverts commit 2c848d4167.

tests/AcDream.App.Tests/Rendering/RenderScenePViewFrameProductTests.cs

@@ -133,6 +133,142 @@ public sealed class RenderScenePViewFrameProductTests
         }
     }
 
+    [Fact]
+    public void Builder_ReusesOrderedIndicesWhileRefreshingDirtyRecords()
+    {
+        using var scene = new ArchRenderScene(Generation);
+        RenderProjectionRecord later = Record(
+            0x0100_0000_0000_0012,
+            RenderProjectionClass.OutdoorStatic);
+        RenderProjectionRecord earlier = Record(
+            0x0100_0000_0000_0011,
+            RenderProjectionClass.OutdoorStatic);
+        scene.Apply(
+        [
+            RenderProjectionDelta.Register(Generation, 1, later),
+            RenderProjectionDelta.Register(Generation, 2, earlier),
+        ]);
+
+        PortalVisibilityFrame portal = Portal(Cell);
+        ClipFrameAssembly clip = FullScreenClip(Cell);
+        ViewconeCuller viewcone =
+            ViewconeCuller.Build(clip, Matrix4x4.Identity);
+        var exchange = new RenderFrameExchange();
+        var builder = new RenderScenePViewFrameBuilder();
+
+        Build(frameSequence: 1);
+        RenderFrameView first = exchange.BorrowLatest(Generation, 1);
+        try
+        {
+            Assert.Equal(
+                [earlier.Id, later.Id],
+                first.OutdoorStaticCandidates.ToArray()
+                    .Select(static record => record.Id));
+        }
+        finally
+        {
+            exchange.Release(in first);
+        }
+
+        scene.ClearDirty();
+        ulong retainedRevision = scene.OpenQuery().IndexRevision;
+        Matrix4x4 movedTransform =
+            Matrix4x4.CreateTranslation(0.25f, 0, 0);
+        RenderProjectionRecord moved = later with
+        {
+            Transform = new RenderTransform(movedTransform),
+            PreviousTransform =
+                new PreviousRenderTransform(
+                    later.Transform.LocalToWorld),
+            Bounds = new RenderWorldBounds(
+                new Vector3(-0.75f, -1, -1),
+                new Vector3(1.25f, 1, 1)),
+        };
+        scene.Apply(
+        [
+            RenderProjectionDelta.Update(
+                RenderProjectionDeltaKind.UpdateTransform,
+                Generation,
+                3,
+                moved),
+        ]);
+        Assert.Equal(
+            retainedRevision,
+            scene.OpenQuery().IndexRevision);
+
+        Build(frameSequence: 2);
+        RenderFrameView second = exchange.BorrowLatest(Generation, 2);
+        try
+        {
+            RenderProjectionRecord projected =
+                second.EntityCandidates.ToArray()
+                    .Single(candidate =>
+                        candidate.Projection.Id == later.Id)
+                    .Projection;
+            Assert.Equal(
+                movedTransform,
+                projected.Transform.LocalToWorld);
+            Assert.Equal(
+                [earlier.Id, later.Id],
+                second.OutdoorStaticCandidates.ToArray()
+                    .Select(static record => record.Id));
+        }
+        finally
+        {
+            exchange.Release(in second);
+        }
+
+        scene.ClearDirty();
+        RenderProjectionRecord reordered = moved with
+        {
+            SortKey = new RenderSortKey(0),
+        };
+        scene.Apply(
+        [
+            RenderProjectionDelta.Update(
+                RenderProjectionDeltaKind.UpdateTransform,
+                Generation,
+                4,
+                reordered),
+        ]);
+        Assert.True(
+            scene.OpenQuery().IndexRevision > retainedRevision);
+
+        Build(frameSequence: 3);
+        RenderFrameView third = exchange.BorrowLatest(Generation, 3);
+        try
+        {
+            Assert.Equal(
+                [later.Id, earlier.Id],
+                third.OutdoorStaticCandidates.ToArray()
+                    .Select(static record => record.Id));
+        }
+        finally
+        {
+            exchange.Release(in third);
+        }
+
+        void Build(ulong frameSequence)
+        {
+            RenderSceneQuery query = scene.OpenQuery();
+            var input = new RenderScenePViewBuildInput(
+                query,
+                new RenderSceneDigest(
+                    query.Generation,
+                    query.Counts,
+                    default),
+                portal,
+                clip,
+                viewcone,
+                [],
+                [Cell],
+                EmptyCellSource.Instance,
+                [],
+                RootIsOutdoor: true);
+            builder.Build(exchange, frameSequence, in input);
+        }
+    }
+
     [Fact]
     public void Controller_MatchesCurrentPViewThenNamesAWithdrawnCandidate()
     {