checkpoint(render): preserve pre-overhaul investigation state

tests/AcDream.Content.Tests/MeshExtractorSolidFaceExtractionTests.cs

@@ -35,6 +35,47 @@ public sealed class MeshExtractorSolidFaceExtractionTests
     private const uint SurfaceTextureId = 0x05000001u;
     private const uint RenderSurfaceId = 0x06000001u;
 
+    [Fact]
+    public void PrepareMeshData_CarriesAuthoredDrawingBspSphereInsteadOfVertexAabbSphere()
+    {
+        var authored = new Sphere
+        {
+            Origin = new Vector3(-0.25f, 0.125f, 0.5f),
+            Radius = 3.125f,
+        };
+        GfxObj gfxObj = BuildQuadGfxObj(SolidSurfaceId, noPos: true);
+        gfxObj.DrawingBSP = new DrawingBSPTree
+        {
+            Root = new DrawingBSPNode { BoundingSphere = authored },
+        };
+        var dats = new FakeMeshExtractorDats();
+        dats.RegisterRootGfxObj(GfxObjId, gfxObj);
+        dats.Register(SolidSurfaceId, new Surface
+        {
+            Type = SurfaceType.Base1Solid,
+            ColorValue = new ColorARGB
+            {
+                Alpha = 255,
+                Red = 12,
+                Green = 34,
+                Blue = 56,
+            },
+        });
+        var extractor = new MeshExtractor(
+            dats,
+            NullLogger.Instance,
+            sideStagedSink: null);
+
+        ObjectMeshData? mesh = extractor.PrepareMeshData(
+            GfxObjId,
+            isSetup: false);
+
+        Assert.NotNull(mesh);
+        Assert.NotNull(mesh!.SelectionSphere);
+        Assert.Equal(authored.Origin, mesh.SelectionSphere.Origin);
+        Assert.Equal(authored.Radius, mesh.SelectionSphere.Radius);
+    }
+
     /// <summary>
     /// One quad polygon, NoPos + Base1Solid: the exact shape of the windmill
     /// axle's own polygons. Must now extract to 4 vertices / 6 indices in a