Improved "respawn where died" functionality (#2831)

Now uses a "last safe position" system instead. This:
-Prevents players from slipping into places they shouldn't via their dead body and then respawning there
-No longer sends players back to spawn if they fall into kill pits
-Adds a safety feature where the kill command always resets back to spawn should a player ever get stuck somewhere

src/g_game.cpp

@@ -1438,6 +1438,7 @@ void FLevelLocals::PlayerReborn (int player)
 	p->cheats |= chasecam;
 	p->Bot = Bot;			//Added by MC:
 	p->settings_controller = settings_controller;
+	p->LastSafePos = p->mo->Pos();
 
 	p->oldbuttons = ~0, p->attackdown = true; p->usedown = true;	// don't do anything immediately
 	p->original_oldbuttons = ~0;

src/gamedata/r_defs.h

@@ -805,6 +805,8 @@ public:
 	void RemoveForceField();
 	int Index() const { return sectornum; }
 
+	bool IsDangerous(const DVector3& pos, double height) const;
+
 	void AdjustFloorClip () const;
 	void SetColor(PalEntry pe, int desat);
 	void SetFade(PalEntry pe);

src/playsim/d_player.h

@@ -435,6 +435,8 @@ public:
 	DAngle ConversationNPCAngle = nullAngle;
 	bool ConversationFaceTalker = false;
 
+	DVector3 LastSafePos = {}; // Mark the last known safe location the player was standing.
+
 	double GetDeltaViewHeight() const
 	{
 		return (mo->FloatVar(NAME_ViewHeight) + crouchviewdelta - viewheight) / 8;

src/playsim/p_mobj.cpp

@@ -5594,16 +5594,13 @@ AActor *FLevelLocals::SpawnPlayer (FPlayerStart *mthing, int playernum, int flag
 
 	PlayerSpawnPickClass(playernum);
 
-	if (( dmflags2 & DF2_SAME_SPAWN_SPOT ) &&
-		( p->playerstate == PST_REBORN ) &&
-		( deathmatch == false ) &&
-		( gameaction != ga_worlddone ) &&
-		( p->mo != NULL ) && 
-		( !(p->mo->Sector->Flags & SECF_NORESPAWN) ) &&
-		( NULL != p->attacker ) &&							// don't respawn on damaging floors
-		( p->mo->Sector->damageamount < TELEFRAG_DAMAGE ))	// this really should be a bit smarter...
+	if ((dmflags2 & DF2_SAME_SPAWN_SPOT) && !deathmatch
+		&& p->mo != nullptr && p->playerstate == PST_REBORN
+		&& gameaction != ga_worlddone
+		&& !(p->mo->Sector->Flags & SECF_NORESPAWN)
+		&& p->LastDamageType != NAME_Suicide)
 	{
-		spawn = p->mo->Pos();
+		spawn = p->LastSafePos;
 		SpawnAngle = p->mo->Angles.Yaw;
 	}
 	else

src/playsim/p_sectors.cpp

@@ -129,6 +129,28 @@ DEFINE_ACTION_FUNCTION_NATIVE(_Sector, NextSpecialSector, P_NextSpecialSector)
 	ACTION_RETURN_POINTER(P_NextSpecialSector(self, type, nogood));
 }
 
+bool sector_t::IsDangerous(const DVector3& pos, double height) const
+{
+	if (damageamount > 0)
+		return true;
+
+	auto cl = dyn_cast<DCeiling>(ceilingdata.Get());
+	if (cl != nullptr && cl->getCrush() > 0)
+		return true;
+
+	for (auto rover : e->XFloor.ffloors)
+	{
+		if ((rover->flags & FF_EXISTS) && rover->model->damageamount > 0
+			&& pos.Z <= rover->top.plane->ZatPoint(pos)
+			&& pos.Z + height >= rover->bottom.plane->ZatPoint(pos))
+		{
+			return true;
+		}
+	}
+
+	return false;
+}
+
 //
 // P_FindLowestFloorSurrounding()
 // FIND LOWEST FLOOR HEIGHT IN SURROUNDING SECTORS

src/playsim/p_user.cpp

@@ -361,6 +361,7 @@ void player_t::CopyFrom(player_t &p, bool copyPSP)
 	MUSINFOactor = p.MUSINFOactor;
 	MUSINFOtics = p.MUSINFOtics;
 	SoundClass = p.SoundClass;
+	LastSafePos = p.LastSafePos;
 	angleOffsetTargets = p.angleOffsetTargets;
 	if (copyPSP)
 	{
@@ -1291,6 +1292,13 @@ void P_PlayerThink (player_t *player)
 		player->SubtitleCounter--;
 	}
 
+	if (player->playerstate == PST_LIVE
+		&& player->mo->Z() <= player->mo->floorz
+		&& !player->mo->Sector->IsDangerous(player->mo->Pos(), player->mo->Height))
+	{
+		player->LastSafePos = player->mo->Pos();
+	}
+
 	// Bots do not think in freeze mode.
 	if (player->mo->Level->isFrozen() && player->Bot != nullptr)
 	{
@@ -1779,7 +1787,8 @@ void player_t::Serialize(FSerializer &arc)
 		("onground", onground)
 		("musinfoactor", MUSINFOactor)
 		("musinfotics", MUSINFOtics)
-		("soundclass", SoundClass);
+		("soundclass", SoundClass)
+		("lastsafepos", LastSafePos);
 
 	if (arc.isWriting ())
 	{