From 0cbbaece3b68e09cfa85a3c63811cbb46a235963 Mon Sep 17 00:00:00 2001
From: Boondorl <59555366+Boondorl@users.noreply.github.com>
Date: Thu, 19 Jan 2023 11:44:57 -0500
Subject: [PATCH] Fixed BlockingLine giving erroneous results

Fixed BlockingLine not clearing properly when xy velocity is 0
---
 src/playsim/p_mobj.cpp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/playsim/p_mobj.cpp b/src/playsim/p_mobj.cpp
index 22961bd67..8ba0ef3ba 100644
--- a/src/playsim/p_mobj.cpp
+++ b/src/playsim/p_mobj.cpp
@@ -1971,6 +1971,7 @@ static double P_XYMovement (AActor *mo, DVector2 scroll)
 	FCheckPosition tm(!!(mo->flags2 & MF2_RIP));
 
 	DAngle oldangle = mo->Angles.Yaw;
+	line_t* blocker = nullptr;
 	do
 	{
 		if (mo->Level->i_compatflags & COMPATF_WALLRUN) pushtime++;
@@ -1986,7 +1987,7 @@ static double P_XYMovement (AActor *mo, DVector2 scroll)
 		{
 			// blocked move
 			AActor *BlockingMobj = mo->BlockingMobj;
-			line_t *BlockingLine = mo->BlockingLine;
+			line_t *BlockingLine = blocker = mo->BlockingLine;
 
 			// [ZZ] 
 			if (!BlockingLine && !BlockingMobj) // hit floor or ceiling while XY movement - sector actions
@@ -2188,6 +2189,9 @@ static double P_XYMovement (AActor *mo, DVector2 scroll)
 		}
 	} while (++step <= steps);
 
+	// Correctly update whether the Actor was truly blocked by a wall or not
+	mo->BlockingLine = blocker;
+
 	// Friction
 
 	if (player && player->mo == mo && player->cheats & CF_NOVELOCITY)
@@ -4057,6 +4061,7 @@ void AActor::Tick ()
 
 		// Handle X and Y velocities
 		BlockingMobj = nullptr;
+		BlockingLine = nullptr;
 		sector_t* oldBlockingCeiling = BlockingCeiling;
 		sector_t* oldBlockingFloor = BlockingFloor;
 		Blocking3DFloor = nullptr;