From e0394ef16a56cbc21996680bc2b4c65ea7158283 Mon Sep 17 00:00:00 2001
From: Boondorl <boondorl@live.com>
Date: Fri, 24 Jan 2025 14:07:33 -0500
Subject: [PATCH] Added flags for angle handling on bounce

Allows for keeping the current angle on bounce or modifying the pitch.
---
 src/playsim/actor.h             |  2 ++
 src/playsim/p_map.cpp           | 12 +++++++++---
 src/playsim/p_mobj.cpp          |  9 +++++++--
 src/scripting/thingdef_data.cpp |  2 ++
 4 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/src/playsim/actor.h b/src/playsim/actor.h
index 14f04e9ee4..edd04cee5f 100644
--- a/src/playsim/actor.h
+++ b/src/playsim/actor.h
@@ -548,6 +548,8 @@ enum ActorBounceFlag
 	BOUNCE_BounceOnUnrips = 1<<16,	// projectile bounces on actors with DONTRIP
 	BOUNCE_NotOnSky = 1<<17,		// Don't bounce on sky floors / ceilings / walls
 	BOUNCE_DEH = 1<<18,				// Flag was set through Dehacked.
+	BOUNCE_KeepAngle = 1<<19,		// Don't change yaw when bouncing off a surface.
+	BOUNCE_ModifyPitch = 1<<20,		// Change pitch when bouncing off a surface.
 
 	BOUNCE_TypeMask = BOUNCE_Walls | BOUNCE_Floors | BOUNCE_Ceilings | BOUNCE_Actors | BOUNCE_AutoOff | BOUNCE_HereticType | BOUNCE_MBF,
 
diff --git a/src/playsim/p_map.cpp b/src/playsim/p_map.cpp
index aaa45e4dc6..04ffa12c06 100644
--- a/src/playsim/p_map.cpp
+++ b/src/playsim/p_map.cpp
@@ -3653,7 +3653,8 @@ bool FSlide::BounceWall(AActor *mo)
 	}
 	moveangle = mo->Vel.Angle();
 	deltaangle = (lineangle * 2) - moveangle;
-	mo->Angles.Yaw = deltaangle;
+	if (!(mo->BounceFlags & BOUNCE_KeepAngle))
+		mo->Angles.Yaw = deltaangle;
 
 	movelen = mo->Vel.XY().Length() * GetWallBounceFactor(mo);
 
@@ -3751,8 +3752,10 @@ bool P_BounceActor(AActor *mo, AActor *BlockingMobj, bool ontop)
 			DAngle angle = BlockingMobj->AngleTo(mo) + DAngle::fromDeg((pr_bounce() % 16) - 8);
 			double speed = mo->VelXYToSpeed() * GetWallBounceFactor(mo); // [GZ] was 0.75, using wallbouncefactor seems more consistent
 			if (fabs(speed) < EQUAL_EPSILON) speed = 0;
-			mo->Angles.Yaw = angle;
-			mo->VelFromAngle(speed);
+			if (!(mo->BounceFlags & BOUNCE_KeepAngle))
+				mo->Angles.Yaw = angle;
+			mo->Vel.X = speed * angle.Cos();
+			mo->Vel.Y = speed * angle.Sin();
 			mo->PlayBounceSound(true, 1.0);
 		}
 		else
@@ -3781,6 +3784,9 @@ bool P_BounceActor(AActor *mo, AActor *BlockingMobj, bool ontop)
 				mo->Vel *= mo->bouncefactor;
 			}
 
+			if (mo->BounceFlags & BOUNCE_ModifyPitch)
+				mo->Angles.Pitch = -VecToAngle(mo->Vel.XY().Length(), mo->Vel.Z);
+
 			mo->PlayBounceSound(true, 1.0);
 			if (mo->BounceFlags & BOUNCE_MBF) // Bring it to rest below a certain speed
 			{
diff --git a/src/playsim/p_mobj.cpp b/src/playsim/p_mobj.cpp
index 61d54c2ece..9bc1854719 100644
--- a/src/playsim/p_mobj.cpp
+++ b/src/playsim/p_mobj.cpp
@@ -1824,7 +1824,8 @@ bool AActor::FloorBounceMissile (secplane_t &plane, bool is3DFloor)
 	if (BounceFlags & (BOUNCE_HereticType | BOUNCE_MBF))
 	{
 		Vel -= norm * dot;
-		AngleFromVel();
+		if (!(BounceFlags & BOUNCE_KeepAngle))
+			AngleFromVel();
 		if (!(BounceFlags & BOUNCE_MBF)) // Heretic projectiles die, MBF projectiles don't.
 		{
 			flags |= MF_INBOUNCE;
@@ -1838,9 +1839,13 @@ bool AActor::FloorBounceMissile (secplane_t &plane, bool is3DFloor)
 	{
 		// The reflected velocity keeps only about 70% of its original speed
 		Vel = (Vel - norm * dot) * bouncefactor;
-		AngleFromVel();
+		if (!(BounceFlags & BOUNCE_KeepAngle))
+			AngleFromVel();
 	}
 
+	if (BounceFlags & BOUNCE_ModifyPitch)
+		Angles.Pitch = -VecToAngle(Vel.XY().Length(), Vel.Z);
+
 	PlayBounceSound(true, 1.0);
 
 	// Set bounce state
diff --git a/src/scripting/thingdef_data.cpp b/src/scripting/thingdef_data.cpp
index fa8d666748..8692936c11 100644
--- a/src/scripting/thingdef_data.cpp
+++ b/src/scripting/thingdef_data.cpp
@@ -407,6 +407,8 @@ static FFlagDef ActorFlagDefs[]=
 	DEFINE_FLAG2(BOUNCE_NotOnShootables, DONTBOUNCEONSHOOTABLES, AActor, BounceFlags),
 	DEFINE_FLAG2(BOUNCE_BounceOnUnrips, BOUNCEONUNRIPPABLES, AActor, BounceFlags),
 	DEFINE_FLAG2(BOUNCE_NotOnSky, DONTBOUNCEONSKY, AActor, BounceFlags),
+	DEFINE_FLAG2(BOUNCE_KeepAngle, KEEPBOUNCEANGLE, AActor, BounceFlags),
+	DEFINE_FLAG2(BOUNCE_ModifyPitch, BOUNCEMODIFIESPITCH, AActor, BounceFlags),
 	
 	DEFINE_FLAG2(OF_Transient, NOSAVEGAME, AActor, ObjectFlags),