fix #451: stabilize portal seam rendering

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

@@ -23,6 +23,7 @@ public sealed class RetailPViewPassExecutorTests
             [
                 "begin",
                 "assemble",
+                "append-look-in-clips",
                 "prepare-clip:3",
                 "indoor-routing",
                 "prepare-cells",
@@ -33,6 +34,7 @@ public sealed class RetailPViewPassExecutorTests
                 "terrain-clip",
                 "clear-routing",
                 "landscape-late",
+                "unattached-particles",
                 "landscape-alpha",
                 "indoor-routing",
                 "indoor-routing",
@@ -272,6 +274,88 @@ public sealed class RetailPViewPassExecutorTests
             executor);
 
         Assert.Contains("look-in-punch", executor.Operations);
+        AssertAppearsInOrder(
+            string.Join('|', executor.Operations),
+            "landscape-early",
+            "unattached-particles",
+            "landscape-static-particles",
+            "landscape-alpha",
+            "look-in-punch",
+            "landscape-late",
+            "landscape-alpha",
+            "interior-depth-clear");
+    }
+
+    [Fact]
+    public void DrawInside_repaints_the_exterior_building_shell_after_its_look_in()
+    {
+        var renderer = new RetailPViewRenderer();
+        using var executor = new RecordingExecutor();
+        LoadedCell root = InteriorWithExit(0xA9B40100u);
+        root.BuildingId = 1u;
+        LoadedCell[] building = NearbyTwoCellBuilding();
+        WorldEntity exteriorShell = Entity(
+            0x700u,
+            isBuildingShell: true,
+            buildingShellAnchorCellId: building[0].CellId);
+
+        renderer.DrawInside(
+            Frame(
+                root,
+                [exteriorShell],
+                nearbyBuildingCells: building,
+                additionalCells: building),
+            executor);
+
+        AssertAppearsInOrder(
+            string.Join('|', executor.Operations),
+            "landscape-early",
+            "look-in-punch",
+            "landscape-building-shell",
+            "landscape-late");
+    }
+
+    [Fact]
+    public void DrawInside_pairs_each_look_in_with_only_its_own_shell_and_alpha_barrier()
+    {
+        var renderer = new RetailPViewRenderer();
+        using var executor = new RecordingExecutor();
+        LoadedCell root = InteriorWithExit(0xA9B40100u);
+        root.BuildingId = 1u;
+        LoadedCell[] first = NearbyTwoCellBuilding();
+        LoadedCell[] second = NearbyTwoCellBuilding(
+            0xA9B40172u,
+            0xA9B40173u,
+            buildingId: 3u);
+        LoadedCell[] buildings = [.. first, .. second];
+        WorldEntity[] shells =
+        [
+            Entity(
+                0x700u,
+                isBuildingShell: true,
+                buildingShellAnchorCellId: first[0].CellId),
+            Entity(
+                0x701u,
+                isBuildingShell: true,
+                buildingShellAnchorCellId: second[0].CellId),
+        ];
+
+        renderer.DrawInside(
+            Frame(
+                root,
+                shells,
+                nearbyBuildingCells: buildings,
+                additionalCells: buildings),
+            executor);
+
+        AssertAppearsInOrder(
+            string.Join('|', executor.Operations),
+            "look-in-punch",
+            "landscape-building-shell",
+            "landscape-static-particles",
+            "landscape-alpha",
+            "look-in-punch",
+            "landscape-building-shell");
     }
 
     [Fact]
@@ -429,20 +513,21 @@ public sealed class RetailPViewPassExecutorTests
         return cell;
     }
 
-    private static LoadedCell[] NearbyTwoCellBuilding()
+    private static LoadedCell[] NearbyTwoCellBuilding(
+        uint vestibuleId = 0xA9B40170u,
+        uint roomId = 0xA9B40171u,
+        uint buildingId = 2u)
     {
-        const uint vestibuleId = 0xA9B40170u;
-        const uint roomId = 0xA9B40171u;
         var vestibule = new LoadedCell
         {
             CellId = vestibuleId,
-            BuildingId = 2u,
+            BuildingId = buildingId,
             WorldTransform = Matrix4x4.Identity,
             InverseWorldTransform = Matrix4x4.Identity,
             Portals =
             [
                 new CellPortalInfo(0xFFFF, 0, 0, 0),
-                new CellPortalInfo(0x0171, 1, 0, 0),
+                new CellPortalInfo((ushort)(roomId & 0xFFFFu), 1, 0, 0),
             ],
             ClipPlanes =
             [
@@ -472,10 +557,17 @@ public sealed class RetailPViewPassExecutorTests
         var room = new LoadedCell
         {
             CellId = roomId,
-            BuildingId = 2u,
+            BuildingId = buildingId,
             WorldTransform = Matrix4x4.Identity,
             InverseWorldTransform = Matrix4x4.Identity,
-            Portals = [new CellPortalInfo(0x0170, 0, 0, 1)],
+            Portals =
+            [
+                new CellPortalInfo(
+                    (ushort)(vestibuleId & 0xFFFFu),
+                    0,
+                    0,
+                    1),
+            ],
         };
         room.PortalPolygons.Add(
         [
@@ -490,7 +582,9 @@ public sealed class RetailPViewPassExecutorTests
     private static WorldEntity Entity(
         uint id,
         uint serverGuid = 0,
-        uint? parentCellId = null) => new()
+        uint? parentCellId = null,
+        bool isBuildingShell = false,
+        uint? buildingShellAnchorCellId = null) => new()
         {
             Id = id,
             ServerGuid = serverGuid,
@@ -499,6 +593,8 @@ public sealed class RetailPViewPassExecutorTests
             Rotation = Quaternion.Identity,
             MeshRefs = [new MeshRef(1u, Matrix4x4.Identity)],
             ParentCellId = parentCellId,
+            IsBuildingShell = isBuildingShell,
+            BuildingShellAnchorCellId = buildingShellAnchorCellId,
         };
 
     private static void AssertAppearsInOrder(string source, params string[] needles)
@@ -566,6 +662,17 @@ public sealed class RetailPViewPassExecutorTests
             return ClipFrameAssembler.Assemble(_clipFrame, portalFrame, reuseAssembly);
         }
 
+        public void AppendLookInClipFrames(
+            IReadOnlyList<PortalVisibilityFrame> lookInFrames,
+            ClipFrameAssembly assembly)
+        {
+            Operations.Add("append-look-in-clips");
+            ClipFrameAssembler.AppendLookInFrames(
+                _clipFrame,
+                lookInFrames,
+                assembly);
+        }
+
         public void PrepareClipFrame(int terrainUploadCount) =>
             Operations.Add($"prepare-clip:{terrainUploadCount}");
 
@@ -574,6 +681,8 @@ public sealed class RetailPViewPassExecutorTests
 
         public void ClearClipRouting() => Operations.Add("clear-routing");
         public void UseIndoorMembershipOnlyRouting() => Operations.Add("indoor-routing");
+        public void UseCellPortalViewRouting(uint cellId, ClipViewSlice slice) =>
+            Operations.Add($"cell-portal-routing:{cellId:X8}:{slice.Slot}");
         public void PrepareCellBatches(RetailPViewFrameInput frame, HashSet<uint> visibleCellIds) =>
             Operations.Add("prepare-cells");
         public void DrawOpaqueCellShells(HashSet<uint> cellIds) => Operations.Add("opaque-shells");
@@ -624,10 +733,37 @@ public sealed class RetailPViewPassExecutorTests
                     request.TupleLandblockId);
             }
         }
+
+        public void DrawLandscapeStaticParticles(
+            RetailPViewFrameInput frame,
+            RetailPViewLandscapeStaticParticleContext context) =>
+            Operations.Add("landscape-static-particles");
+        public void DrawLandscapeBuildingShellSlice(
+            RetailPViewFrameInput frame,
+            RetailPViewLandscapeBuildingShellSliceContext context)
+        {
+            Operations.Add("landscape-building-shell");
+            if (context.EntityDraw is RenderFrameEntityDrawRequest request)
+            {
+                RenderFrameView view = request.View;
+                DrawEntityRoute(
+                    frame.Camera,
+                    in view,
+                    request.Route,
+                    request.RouteIndex,
+                    request.CellId,
+                    request.TupleLandblockId);
+            }
+        }
         public void ClearInteriorDepth() => Operations.Add("interior-depth-clear");
         public void DrawExitPortalMask(RetailPViewFrameInput frame, RetailPViewCellSliceContext context) => Operations.Add("exit-mask");
-        public void DrawLookInPortalPunch(RetailPViewFrameInput frame, RetailPViewCellSliceContext context) => Operations.Add("look-in-punch");
-        public void DrawUnattachedSceneParticles(RetailPViewFrameInput frame) => Operations.Add("unattached-particles");
+        public void DrawLookInPortalPunch(
+            RetailPViewFrameInput frame,
+            RetailPViewCellSliceContext context,
+            int portalIndex) => Operations.Add("look-in-punch");
+        public void DrawUnattachedSceneParticles(
+            RetailPViewFrameInput frame,
+            ClipViewSlice slice) => Operations.Add("unattached-particles");
         public void FlushLandscapeAlpha() => Operations.Add("landscape-alpha");
         public void DrawCellParticles(RetailPViewFrameInput frame, RetailPViewCellSliceContext context) => Operations.Add("cell-particles");
         public void DrawDynamicsParticles(