From d32dcd5f8eb54720719d521b44d81bfcc7a2bf61 Mon Sep 17 00:00:00 2001
From: Mitchell Richters <mjr4077au@gmail.com>
Date: Tue, 5 Jan 2021 11:01:31 +1100
Subject: [PATCH] - Exhumed: Fix player panning when walking up/down steps
 while horizon is 0.

---
 source/core/gameinput.h       | 12 ++++++++++++
 source/exhumed/src/player.cpp | 26 ++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/source/core/gameinput.h b/source/core/gameinput.h
index 357febc07..26d61fb77 100644
--- a/source/core/gameinput.h
+++ b/source/core/gameinput.h
@@ -39,6 +39,18 @@ struct PlayerHorizon
 		}
 	}
 
+	void addadjustment(fixed_t value)
+	{
+		if (!SyncInput())
+		{
+			adjustment += value;
+		}
+		else
+		{
+			horiz += q16horiz(value);
+		}
+	}
+
 	void resetadjustment()
 	{
 		adjustment = 0;
diff --git a/source/exhumed/src/player.cpp b/source/exhumed/src/player.cpp
index b71fbd3ab..6de420549 100644
--- a/source/exhumed/src/player.cpp
+++ b/source/exhumed/src/player.cpp
@@ -1167,6 +1167,32 @@ void FuncPlayer(int a, int nDamage, int nRun)
             }
 
 sectdone:
+            static bool plrFalling = false;
+            if (!PlayerList[nPlayer].horizon.horiz.asbuild() || plrFalling)
+            {
+                // Calculate base pan amount based on how much the player is falling.
+                fixed_t dVertPan = (spr_z - sprite[nPlayerSprite].z) << 9;
+                if (dVertPan != 0)
+                {
+                    fixed_t adjustment;
+
+                    if (dVertPan >= IntToFixed(4))
+                        adjustment = IntToFixed(4);
+                    else if (dVertPan <= -IntToFixed(4))
+                        adjustment = -IntToFixed(4);
+                    else
+                        adjustment = dVertPan << 1;
+
+                    PlayerList[nPlayer].horizon.addadjustment(adjustment);
+                    plrFalling = true;
+                }
+                else
+                {
+                    sPlayerInput[nPlayer].actions |= SB_CENTERVIEW;
+                    plrFalling = false;
+                }
+            }
+
             playerX -= sprite[nPlayerSprite].x;
             playerY -= sprite[nPlayerSprite].y;