fix(world): remove non-retail portal exit fade

src/AcDream.App/Rendering/TeleportViewPlaneController.cs

@@ -8,14 +8,16 @@ namespace AcDream.App.Rendering;
 /// (<c>0x004D6E30</c>) eases SmartBox's view-plane distance between the
 /// active game's value and <c>TRANSITION_VIEW_PLANE_DISTANCE = 0.001</c>.
 /// <c>Render::set_vdst</c> (<c>0x0054B240</c>) converts that distance back to
-/// FOV and adjusts the near plane. This is the wide projection warp visible
-/// while the destination world emerges from black.
+/// FOV and adjusts the near plane. At the exit edge retail swaps directly
+/// from portal space to the destination world at the transition projection;
+/// there is no black-alpha compositor between them.
 /// </summary>
 public sealed class TeleportViewPlaneController
 {
     public const float TransitionViewPlaneDistance = 0.001f;
 
     private float _gameViewPlaneDistance = 1f;
+    private readonly ProjectionOverrideCamera _projectionCamera = new();
 
     public bool Enabled { get; private set; }
     public float CurrentViewPlaneDistance { get; private set; } = 1f;
@@ -38,20 +40,42 @@ public sealed class TeleportViewPlaneController
     }
 
     /// <summary>
-    /// Apply the four retail fade-state branches. Their projection blend is
-    /// numerically the same table-driven level as the black fade: normal to
-    /// 0.001 on fade-out, and 0.001 back to normal on fade-in.
+    /// Apply retail's view-plane state machine. Here "fade" is retail's state
+    /// name for a projection transition: normal to 0.001 on fade-out, and
+    /// 0.001 back to normal on fade-in. A logout transition retains the
+    /// captured override during stable Tunnel; <c>EndTeleportAnimation</c>
+    /// (<c>0x004D65D5</c>) releases it when entering TunnelContinue.
     /// </summary>
     public void Update(TeleportAnimSnapshot snapshot)
     {
-        Enabled = snapshot.State is TeleportAnimState.WorldFadeOut
-            or TeleportAnimState.TunnelFadeIn
-            or TeleportAnimState.TunnelFadeOut
-            or TeleportAnimState.WorldFadeIn;
+        switch (snapshot.State)
+        {
+            case TeleportAnimState.WorldFadeOut:
+            case TeleportAnimState.TunnelFadeIn:
+            case TeleportAnimState.TunnelFadeOut:
+            case TeleportAnimState.WorldFadeIn:
+                Enabled = true;
+                CurrentViewPlaneDistance = Lerp(
+                    _gameViewPlaneDistance,
+                    TransitionViewPlaneDistance,
+                    snapshot.ViewPlaneBlend);
+                break;
 
-        CurrentViewPlaneDistance = Enabled
-            ? Lerp(_gameViewPlaneDistance, TransitionViewPlaneDistance, snapshot.FadeAlpha)
-            : _gameViewPlaneDistance;
+            case TeleportAnimState.Tunnel:
+                // Retail preserves the captured FOV override through the
+                // logout path's stable tunnel. A normal portal begins in
+                // Tunnel with no override, so its disabled state is retained.
+                if (Enabled)
+                    CurrentViewPlaneDistance = _gameViewPlaneDistance;
+                break;
+
+            case TeleportAnimState.TunnelContinue:
+            case TeleportAnimState.Off:
+            default:
+                Enabled = false;
+                CurrentViewPlaneDistance = _gameViewPlaneDistance;
+                break;
+        }
     }
 
     public void Reset()
@@ -93,6 +117,39 @@ public sealed class TeleportViewPlaneController
         return Matrix4x4.CreatePerspectiveFieldOfView(fov, aspect, near, far);
     }
 
+    /// <summary>
+    /// Decorate the active camera with the same projection returned by
+    /// <see cref="Apply(Matrix4x4)"/>. Retail's <c>Render::set_vdst</c> is
+    /// global to every 3-D draw; callers must pass this returned camera to
+    /// terrain, meshes, particles, sky, weather, and portal-cell rendering so
+    /// rasterization and frustum culling cannot use different projections.
+    /// </summary>
+    public ICamera ApplyTo(ICamera baseCamera)
+    {
+        ArgumentNullException.ThrowIfNull(baseCamera);
+        _projectionCamera.Update(baseCamera, Apply(baseCamera.Projection));
+        return _projectionCamera;
+    }
+
     private static float Lerp(float from, float to, float amount) =>
         from + (to - from) * Math.Clamp(amount, 0f, 1f);
+
+    private sealed class ProjectionOverrideCamera : ICamera
+    {
+        private ICamera _source = null!;
+
+        public Matrix4x4 View => _source.View;
+        public Matrix4x4 Projection { get; private set; } = Matrix4x4.Identity;
+        public float Aspect
+        {
+            get => _source.Aspect;
+            set => _source.Aspect = value;
+        }
+
+        public void Update(ICamera source, Matrix4x4 projection)
+        {
+            _source = source;
+            Projection = projection;
+        }
+    }
 }