feat(render): implement Campaign AR and terrain fidelity

tests/AcDream.Core.Tests/World/SkyDescLoaderTests.cs

@@ -1,8 +1,10 @@
 using System.Collections.Generic;
 using System.Numerics;
+using AcDream.Core.Content;
 using AcDream.Core.World;
 using DatReaderWriter.DBObjs;
 using DatReaderWriter.Enums;
+using DatReaderWriter.Lib.IO;
 using DatReaderWriter.Types;
 using Xunit;
 
@@ -126,6 +128,55 @@ public sealed class SkyDescLoaderTests
         Assert.Equal(0x01004C44u, obj.GfxObjId);
         Assert.Equal(0x3300042Cu, obj.PesObjectId);
         Assert.True(obj.IsPostScene);
+        Assert.Equal(Vector3.Zero, obj.AuthoredSortCenter);
+    }
+
+    [Fact]
+    public void LoadFromRegion_WithDatSourceCarriesDefaultAndReplacementSortCenters()
+    {
+        const uint defaultId = 0x01001348u;
+        const uint replacementId = 0x01001F6Au;
+        Vector3 defaultCenter = new(1050f, 0f, 0f);
+        Vector3 replacementCenter = new(2066.82f, 552.99f, 0f);
+        Region region = MakeRegion(dirBright: 1f, rBgrOrder: 255);
+        DayGroup group = region.SkyInfo!.DayGroups[0];
+        group.SkyObjects.Add(new SkyObject
+        {
+            DefaultGfxObjectId = defaultId,
+        });
+        group.SkyTime[0].SkyObjReplace.Add(new SkyObjectReplace
+        {
+            ObjectIndex = 0,
+            GfxObjId = replacementId,
+        });
+        var dats = new FakeDatObjectSource();
+        dats.Add(defaultId, new GfxObj { SortCenter = defaultCenter });
+        dats.Add(replacementId, new GfxObj { SortCenter = replacementCenter });
+
+        LoadedSkyDesc loaded = Assert.IsType<LoadedSkyDesc>(
+            SkyDescLoader.LoadFromRegion(region, dats));
+
+        Assert.Equal(defaultCenter,
+            Assert.Single(loaded.DayGroups[0].SkyObjects).AuthoredSortCenter);
+        Assert.Equal(replacementCenter,
+            Assert.Single(loaded.DayGroups[0].SkyTimes[0].Replaces).AuthoredSortCenter);
+    }
+
+    [Fact]
+    public void LoadFromRegion_FailedOptionalSortCenterLookupCannotFailSkyLoading()
+    {
+        Region region = MakeRegion(dirBright: 1f, rBgrOrder: 255);
+        region.SkyInfo!.DayGroups[0].SkyObjects.Add(new SkyObject
+        {
+            DefaultGfxObjectId = 0x01001348u,
+        });
+
+        LoadedSkyDesc loaded = Assert.IsType<LoadedSkyDesc>(
+            SkyDescLoader.LoadFromRegion(region, new ThrowingDatObjectSource()));
+
+        Assert.Equal(
+            Vector3.Zero,
+            Assert.Single(loaded.DayGroups[0].SkyObjects).AuthoredSortCenter);
     }
 
     [Fact]
@@ -201,4 +252,31 @@ public sealed class SkyDescLoaderTests
         // At begin → begin angle.
         Assert.Equal(0f,  obj.CurrentAngle(0.25f), precision: 2);
     }
+
+    private sealed class FakeDatObjectSource : IDatObjectSource
+    {
+        private readonly Dictionary<uint, IDBObj> _objects = [];
+
+        internal void Add(uint id, IDBObj value) => _objects[id] = value;
+
+        public T Get<T>(uint fileId) where T : IDBObj =>
+            _objects.TryGetValue(fileId, out IDBObj? value) && value is T typed
+                ? typed
+                : default!;
+
+        public bool TryGet<T>(uint fileId, out T value) where T : IDBObj
+        {
+            value = Get<T>(fileId);
+            return value is not null;
+        }
+    }
+
+    private sealed class ThrowingDatObjectSource : IDatObjectSource
+    {
+        public T Get<T>(uint fileId) where T : IDBObj =>
+            throw new InvalidOperationException("synthetic DAT lookup failure");
+
+        public bool TryGet<T>(uint fileId, out T value) where T : IDBObj =>
+            throw new InvalidOperationException("synthetic DAT lookup failure");
+    }
 }