BR-2 commit 2: far-Z PUNCH on building entry apertures (outdoor + look-in)

Mirror of commit 1's seal: the punch half of retail's invisible portal
depth writes (DrawPortalPolyInternal maxZ1, Ghidra 0x0059bc90;
ConstructView(CBldPortal) mode-1, pc:433827).

Generalized DrawRetailPViewExitPortalSeal -> DrawRetailPViewPortalDepthWrite
with retail's maxZ1/maxZ2 selector (forceFarZ):
- INTERIOR root: forceFarZ=false (SEAL, true depth) - unchanged from c1.
- OUTDOOR root + DrawPortal look-in: forceFarZ=true (PUNCH, far depth) -
  erase the terrain depth inside a flooded building's entry aperture so
  the interior shows THROUGH the doorway against the nearer front-ground.

Architectural note (divergence from retail ORDER, same RESULT): retail
draws the shell LAST (DrawBuilding Draw(part,1) punch -> draw interior ->
Draw(part,0) shell) so the shell closes everything outside the punch. Our
pipeline draws the building shell FIRST (it is an outdoor WorldEntity in
the landscape pass), so the outside-the-aperture wall occlusion is already
in the depth buffer when interiors draw - we need ONLY the punch for
in-aperture visibility, no shell reorder. The punch is confined to each
door polygon clipped to its slice (NOT a full clear), so it does not
reintroduce the 'cellar paints over everything' hazard that gated the old
outdoor ClearDepthSlice to null.

DrawExitPortalMasks is now wired on the outdoor-root DrawInside context and
the DrawPortal look-in context (both previously null -> no-op).

Suites: build green, App 226 green, Core 1398 + 4 pre-existing #99-era.
NEEDS VISUAL GATE (batched with BR-3): outdoor interiors-through-doorways
must not bleed; cellar grass-sweep (#108) gone; tower stairs near+far.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/AcDream.App/Rendering/GameWindow.cs

@@ -7656,9 +7656,12 @@ public sealed class GameWindow : IDisposable
                             _gl.DepthMask(true);   // depth clears honor glDepthMask (c4df241 lesson)
                             _gl.Clear(ClearBufferMask.DepthBufferBit);
                         },
-                    DrawExitPortalMasks = clipRoot.IsOutdoorNode
+                    // BR-2: interior roots SEAL exit doors at true depth (#108);
-                        ? null
+                    // outdoor roots PUNCH building entry apertures to far-Z so
-                        : sliceCtx => DrawRetailPViewExitPortalSeal(sliceCtx, envCellViewProj),
+                    // flooded interiors show through doorways from outside.
+                    DrawExitPortalMasks = sliceCtx =>
+                        DrawRetailPViewPortalDepthWrite(sliceCtx, envCellViewProj,
+                            forceFarZ: clipRoot.IsOutdoorNode),
                     DrawCellParticles = sliceCtx =>
                         DrawRetailPViewCellParticles(sliceCtx, camera, camPos),
                     EmitDiagnostics = result =>
@@ -7804,6 +7807,11 @@ public sealed class GameWindow : IDisposable
                                 MaxSeedDistance = 48f,
                                 LandblockEntries = _worldState.LandblockEntries,
                                 SetTerrainClipUbo = uboId => _terrain?.SetClipUbo(uboId),
+                                // BR-2: outside-looking-in — PUNCH building entry apertures
+                                // to far-Z so the flooded interior shows through the doorway.
+                                DrawExitPortalMasks = sliceCtx =>
+                                    DrawRetailPViewPortalDepthWrite(sliceCtx, envCellViewProj,
+                                        forceFarZ: true),
                             });
 
                         if (portalResult is not null)
@@ -9559,18 +9567,29 @@ public sealed class GameWindow : IDisposable
         DisableClipDistances();
     }
 
-    // BR-2 seal: re-stamp the TRUE depth of every outside-leading portal of this
+    // BR-2: retail's invisible portal depth writes on every outside-leading
-    // cell, clipped to the slice's view region — retail PView::DrawCells loop 1
+    // portal (other_cell_id==0xFFFF) of this cell, clipped to the slice's view
-    // (Ghidra 0x005a4840, pc:432783-432786): after the landscape draws through
+    // region — D3DPolyRender::DrawPortalPolyInternal (Ghidra 0x0059bc90),
-    // the outside views and the depth buffer is cleared, every portal with
+    // dispatched by PView::DrawCells (Ghidra 0x005a4840). The forceFarZ flag is
-    // other_cell_id==0xFFFF gets DrawPortalPolyInternal(poly, false) — an
+    // retail's maxZ1(true)/maxZ2(false) selector:
-    // invisible depth write at the portal plane, so interior geometry FARTHER
+    //
-    // than the doorway z-fails inside the aperture and the terrain seen through
+    //  • INTERIOR root (forceFarZ=false → SEAL, true depth): after the full
-    // it keeps its pixels (#108). Wiring only — the draw lives in
+    //    depth clear, stamp the door plane so interior geometry beyond the door
-    // PortalDepthMaskRenderer.
+    //    z-fails inside the aperture and the terrain drawn through the outside
-    private void DrawRetailPViewExitPortalSeal(
+    //    view keeps its pixels (#108).
+    //  • OUTDOOR root / look-in (forceFarZ=true → PUNCH, far depth): after the
+    //    landscape + shell drew, erase the terrain depth inside the building's
+    //    entry aperture so the flooded interior shows THROUGH the doorway
+    //    against the nearer front-ground. Our pipeline draws the shell FIRST
+    //    (as an outdoor entity in the landscape pass), so — unlike retail's
+    //    shell-LAST order — we get the outside-the-aperture wall occlusion for
+    //    free and need only the punch for in-aperture visibility (no reorder).
+    //
+    // Wiring only — the draw lives in PortalDepthMaskRenderer.
+    private void DrawRetailPViewPortalDepthWrite(
         AcDream.App.Rendering.RetailPViewCellSliceContext sliceCtx,
-        System.Numerics.Matrix4x4 viewProjection)
+        System.Numerics.Matrix4x4 viewProjection,
+        bool forceFarZ)
     {
         if (_portalDepthMask is null)
             return;
@@ -9581,7 +9600,7 @@ public sealed class GameWindow : IDisposable
         for (int i = 0; i < cell.Portals.Count; i++)
         {
             if (cell.Portals[i].OtherCellId != 0xFFFF)
-                continue;   // seals apply to portals leading OUTSIDE only
+                continue;   // depth writes apply to portals leading OUTSIDE only
             if (i >= cell.PortalPolygons.Count)
                 break;
             var localVerts = cell.PortalPolygons[i];
@@ -9592,7 +9611,7 @@ public sealed class GameWindow : IDisposable
             for (int v = 0; v < n; v++)
                 world[v] = System.Numerics.Vector3.Transform(localVerts[v], cell.WorldTransform);
 
-            _portalDepthMask.DrawDepthFan(world[..n], viewProjection, sliceCtx.Slice.Planes, forceFarZ: false);
+            _portalDepthMask.DrawDepthFan(world[..n], viewProjection, sliceCtx.Slice.Planes, forceFarZ);
         }
     }