refactor(render): extract world scene frame owner

Move fallback and PView world drawing, shared alpha, particles, visibility, selection, and diagnostics behind focused frame owners. Make exceptional frames failure-atomic by restoring the shared GL baseline and preserving primary alpha failures through cleanup.

Co-authored-by: Codex <codex@openai.com>

src/AcDream.App/Rendering/WorldSceneRuntimeSources.cs

@@ -0,0 +1,117 @@
+using System.Numerics;
+using AcDream.App.Input;
+using AcDream.App.Streaming;
+using AcDream.Core.Physics;
+using AcDream.Core.World;
+
+namespace AcDream.App.Rendering;
+
+internal interface IWorldSceneSkyStateSource
+{
+    DayGroupData? ActiveDayGroup { get; }
+
+    float DayFraction { get; }
+}
+
+/// <summary>
+/// Holds the selected retail day group beside the world clock that provides
+/// its current interpolation point. Day-group selection remains an update-time
+/// concern; render owners receive this read-only seam.
+/// </summary>
+internal sealed class WorldSceneSkyState : IWorldSceneSkyStateSource
+{
+    private readonly WorldTimeService _worldTime;
+
+    public WorldSceneSkyState(WorldTimeService worldTime)
+    {
+        _worldTime = worldTime ?? throw new ArgumentNullException(nameof(worldTime));
+    }
+
+    public DayGroupData? ActiveDayGroup { get; set; }
+
+    public float DayFraction => (float)_worldTime.DayFraction;
+}
+
+internal interface IWorldSceneEntitySource
+{
+    IEnumerable<(uint LandblockId, Vector3 AabbMin, Vector3 AabbMax,
+        IReadOnlyList<WorldEntity> Entities,
+        IReadOnlyDictionary<uint, WorldEntity>? AnimatedById)> LandblockEntries
+    { get; }
+
+    IEnumerable<(uint LandblockId, Vector3 AabbMin, Vector3 AabbMax)> LandblockBounds { get; }
+}
+
+internal sealed class RuntimeWorldSceneEntitySource : IWorldSceneEntitySource
+{
+    private readonly GpuWorldState _world;
+
+    public RuntimeWorldSceneEntitySource(GpuWorldState world)
+    {
+        _world = world ?? throw new ArgumentNullException(nameof(world));
+    }
+
+    public IEnumerable<(uint LandblockId, Vector3 AabbMin, Vector3 AabbMax,
+        IReadOnlyList<WorldEntity> Entities,
+        IReadOnlyDictionary<uint, WorldEntity>? AnimatedById)> LandblockEntries =>
+        _world.LandblockEntries;
+
+    public IEnumerable<(uint LandblockId, Vector3 AabbMin, Vector3 AabbMax)> LandblockBounds =>
+        _world.LandblockBounds;
+}
+
+internal interface IWorldScenePViewDiagnosticSource
+{
+    Vector3 RawPlayerPositionOr(Vector3 fallback);
+
+    float PlayerYaw { get; }
+
+    float? SampleTerrainZ(float worldX, float worldY);
+
+    CameraCellResolution CameraCellResolution { get; }
+}
+
+internal sealed class RuntimeWorldScenePViewDiagnosticSource :
+    IWorldScenePViewDiagnosticSource
+{
+    private readonly ILocalPlayerControllerSource _player;
+    private readonly PhysicsEngine _physics;
+    private readonly CellVisibility _visibility;
+
+    public RuntimeWorldScenePViewDiagnosticSource(
+        ILocalPlayerControllerSource player,
+        PhysicsEngine physics,
+        CellVisibility visibility)
+    {
+        _player = player ?? throw new ArgumentNullException(nameof(player));
+        _physics = physics ?? throw new ArgumentNullException(nameof(physics));
+        _visibility = visibility ?? throw new ArgumentNullException(nameof(visibility));
+    }
+
+    public Vector3 RawPlayerPositionOr(Vector3 fallback) =>
+        _player.Controller?.Position ?? fallback;
+
+    public float PlayerYaw => _player.Controller?.Yaw ?? 0f;
+
+    public float? SampleTerrainZ(float worldX, float worldY) =>
+        _physics.SampleTerrainZ(worldX, worldY);
+
+    public CameraCellResolution CameraCellResolution =>
+        _visibility.LastCameraCellResolution;
+}
+
+internal interface IWorldSceneDebugStateSource
+{
+    bool CollisionWireframesVisible { get; }
+}
+
+internal sealed class WorldSceneDebugState : IWorldSceneDebugStateSource
+{
+    public bool CollisionWireframesVisible { get; private set; }
+
+    public bool ToggleCollisionWireframes()
+    {
+        CollisionWireframesVisible = !CollisionWireframesVisible;
+        return CollisionWireframesVisible;
+    }
+}