From 88caa0dc8b783f234fefcc2f1e9f14a351cef835 Mon Sep 17 00:00:00 2001
From: Erik <erik.nihlen@gmail.com>
Date: Sun, 7 Jun 2026 20:18:33 +0200
Subject: [PATCH] fix(render): outdoor-root skips the full-screen depth clear
 (cellar/buildings no longer draw over the world)
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Cutover-flip follow-up (issues 1+2 from the visual gate). After the flip an outdoor-node frame ran DrawInside with a full-screen OutsideView slice (Step A) whose ClearDepthSlice wiped the ENTIRE depth buffer AFTER terrain/exteriors/player drew — so the flooded building interior shells (cellars) drew over everything: the cellar painted in front of the player from outside, and distant building interiors showed through the ground in the open field.

The depth clear is a doorway look-in trick (clear a small door region so the cell seen through it draws over the terrain drawn through it). It is wrong for the full-screen base terrain of the outdoor root. Skip it there (ClearDepthSlice=null when clipRoot is the outdoor node); interiors now depth-test against terrain + exteriors and appear only through real door openings. Interior roots keep the doorway clear unchanged.

App 216/0, build green. Visual gate pending (player must be outdoors to exercise the outdoor root).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 src/AcDream.App/Rendering/GameWindow.cs | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/src/AcDream.App/Rendering/GameWindow.cs b/src/AcDream.App/Rendering/GameWindow.cs
index 481eb6fe..a1a96a34 100644
--- a/src/AcDream.App/Rendering/GameWindow.cs
+++ b/src/AcDream.App/Rendering/GameWindow.cs
@@ -7527,13 +7527,24 @@ public sealed class GameWindow : IDisposable
                             renderSky,
                             kf,
                             environOverrideActive),
-                    ClearDepthSlice = slice =>
-                    {
-                        bool zc = BeginDoorwayScissor(true, slice.NdcAabb);
-                        _gl.Clear(ClearBufferMask.DepthBufferBit);
-                        if (zc)
-                            _gl.Disable(EnableCap.ScissorTest);
-                    },
+                    // The depth clear is a doorway "look-in" trick: clear depth inside a door/window
+                    // region so the cell seen THROUGH it draws over the terrain drawn through that
+                    // region (the indoor root looking out). For the OUTDOOR-node root the only
+                    // OutsideView slice is the FULL-SCREEN base terrain, so clearing its depth wipes the
+                    // entire depth buffer AFTER terrain/exteriors/player drew — the flooded building
+                    // interiors (cellars) would then paint over everything (cellar in front of the
+                    // player; building interiors through the ground). Outdoors the interiors must
+                    // depth-test against terrain+exteriors and appear only through real door openings,
+                    // so issue NO depth clear. Interior roots keep the doorway clear (unchanged).
+                    ClearDepthSlice = ReferenceEquals(clipRoot, _outdoorNode)
+                        ? null
+                        : slice =>
+                        {
+                            bool zc = BeginDoorwayScissor(true, slice.NdcAabb);
+                            _gl.Clear(ClearBufferMask.DepthBufferBit);
+                            if (zc)
+                                _gl.Disable(EnableCap.ScissorTest);
+                        },
                     DrawCellParticles = sliceCtx =>
                         DrawRetailPViewCellParticles(sliceCtx, camera, camPos),
                     EmitDiagnostics = result =>