From 454d88ed8ed554c45c82c09f6e43f2fb48efdd47 Mon Sep 17 00:00:00 2001
From: Erik <erik.nihlen@gmail.com>
Date: Thu, 14 May 2026 07:19:36 +0200
Subject: [PATCH] fix(B.4c): correct NonCombat stance value (0x3D, not 0x01) +
 read spawn.MotionState

Visual test revealed doors rendered halfway in the ground because the
spawn-time SetCycle seed never fired:

- Spec specified NonCombat stance = 0x01, but ACE's MotionStance.NonCombat
  is 0x3D (61). The cycle key is `0x80000000 | stance`, so the correct
  initial style is 0x8000003D, not 0x80000001.
- HasCycle(0x80000001, ...) always returned false -> SetCycle was skipped
  -> sequencer left with no current motion -> Advance(dt) returned empty
  frames -> per-frame MeshRefs rebuild at line 7691 set every part to
  (origin, identity) -> door parts collapsed to the entity origin (which
  sits at the door's pivot, halfway underground for inn doors).

Fix:
1. Rename inline `NonCombatStance` -> `NonCombatStyle` and use the correct
   0x8000003D value.
2. Defensively prefer spawn.MotionState?.Stance when present (the wire
   may carry an explicit non-NonCombat stance for unusual doors), falling
   back to NonCombat. Mirrors OnLiveMotionUpdated's existing pattern at
   line 3148: `uint fullStyle = stance != 0 ? (0x80000000u | (uint)stance) : ae.Sequencer.CurrentStyle`.
3. Extend [door-anim] registered diagnostic to include initialStyle so
   future visual tests can verify the stance value at a glance.

Verified by reading the prior visual test's log: ACE broadcasts UMs
with stance=0x003D and the runtime sequencer keyed cycles by
style=0x8000003D. Same value now used at spawn.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
---
 src/AcDream.App/Rendering/GameWindow.cs | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/src/AcDream.App/Rendering/GameWindow.cs b/src/AcDream.App/Rendering/GameWindow.cs
index 9fc7279..ecd3bda 100644
--- a/src/AcDream.App/Rendering/GameWindow.cs
+++ b/src/AcDream.App/Rendering/GameWindow.cs
@@ -2832,14 +2832,29 @@ public sealed class GameWindow : IDisposable
                 {
                     var sequencer = new AcDream.Core.Physics.AnimationSequencer(setup, mtable, _animLoader);
 
-                    const uint NonCombatStance = 0x80000001u;
+                    // Style key is `0x80000000 | stance`. ACE's MotionStance.NonCombat
+                    // is 0x3D (61 decimal), NOT 0x01. Verified live: ACE broadcasts
+                    // UpdateMotion with stance=0x003D and the sequencer keys cycles
+                    // by style=0x8000003D. An earlier B.4c seed used the wrong
+                    // 0x80000001 value, which made HasCycle always return false ->
+                    // SetCycle never fired -> sequencer empty -> Advance returned
+                    // no frames -> per-frame tick collapsed all door parts to the
+                    // entity origin (visible as "door halfway in the ground").
+                    const uint NonCombatStyle = 0x8000003Du;
                     const uint MotionOn = 0x4000000Bu;   // ACE MotionCommand.On (door open)
                     const uint MotionOff = 0x4000000Cu;  // ACE MotionCommand.Off (door closed)
                     const uint EtherealPs = 0x4u;
+                    // Prefer the spawn's wire-level stance if provided; else default
+                    // to NonCombat. (Doors normally don't carry an initial MotionState
+                    // on spawn — falling back to NonCombat matches ACE Door.cs:43.)
+                    ushort spawnStance = spawn.MotionState?.Stance ?? 0;
+                    uint initialStyle = spawnStance != 0
+                        ? (0x80000000u | (uint)spawnStance)
+                        : NonCombatStyle;
                     uint spawnState = spawn.PhysicsState ?? 0u;
                     uint initialCycle = (spawnState & EtherealPs) != 0 ? MotionOn : MotionOff;
-                    if (sequencer.HasCycle(NonCombatStance, initialCycle))
-                        sequencer.SetCycle(NonCombatStance, initialCycle);
+                    if (sequencer.HasCycle(initialStyle, initialCycle))
+                        sequencer.SetCycle(initialStyle, initialCycle);
 
                     var template = new (uint, IReadOnlyDictionary<uint, uint>?)[meshRefs.Count];
                     for (int i = 0; i < meshRefs.Count; i++)
@@ -2861,7 +2876,7 @@ public sealed class GameWindow : IDisposable
 
                     if (AcDream.Core.Physics.PhysicsDiagnostics.ProbeBuildingEnabled)
                         Console.WriteLine(System.FormattableString.Invariant(
-                            $"[door-anim] registered guid=0x{spawn.Guid:X8} entityId=0x{entity.Id:X8} mtable=0x{mtableId:X8} initialCycle=0x{initialCycle:X8}"));
+                            $"[door-anim] registered guid=0x{spawn.Guid:X8} entityId=0x{entity.Id:X8} mtable=0x{mtableId:X8} initialStyle=0x{initialStyle:X8} initialCycle=0x{initialCycle:X8}"));
                 }
             }
         }