From 6c12a8de1282e6e3b79244a775d531c68c54503d Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@users.noreply.github.com>
Date: Tue, 21 Sep 2021 20:31:10 +0200
Subject: [PATCH] - properly track whether some action in the current frame may
 have triggered a dynamic light activation.

---
 src/gamedata/g_mapinfo.h           |  1 +
 src/p_setup.cpp                    |  3 +++
 src/playsim/a_dynlight.cpp         |  3 +++
 src/playsim/dthinker.cpp           |  6 ++++--
 src/playsim/p_mobj.cpp             | 12 ++++++++++--
 wadsrc/static/zscript/constants.zs |  9 +++++++++
 6 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/src/gamedata/g_mapinfo.h b/src/gamedata/g_mapinfo.h
index 9f74728542..4ed13e5baa 100644
--- a/src/gamedata/g_mapinfo.h
+++ b/src/gamedata/g_mapinfo.h
@@ -260,6 +260,7 @@ enum ELevelFlags : unsigned int
 	LEVEL3_NOSHADOWMAP			= 0x00010000,	// disables shadowmaps for a given level.
 	LEVEL3_AVOIDMELEE			= 0x00020000,	// global flag needed for proper MBF support.
 	LEVEL3_NOJUMPDOWN			= 0x00040000,	// only for MBF21. Inverse of MBF's dog_jumping flag.
+	LEVEL3_LIGHTCREATED			= 0x00080000,	// a light had been created in the last frame
 };
 
 
diff --git a/src/p_setup.cpp b/src/p_setup.cpp
index b96830a1f6..d05865820c 100644
--- a/src/p_setup.cpp
+++ b/src/p_setup.cpp
@@ -598,6 +598,9 @@ void P_SetupLevel(FLevelLocals *Level, int position, bool newGame)
 
 	auto it = Level->GetThinkerIterator<AActor>();
 	AActor* ac;
+
+	Level->flags3 |= LEVEL3_LIGHTCREATED;
+
 	// Initial setup of the dynamic lights.
 	while ((ac = it.Next()))
 	{
diff --git a/src/playsim/a_dynlight.cpp b/src/playsim/a_dynlight.cpp
index 4750dddfaf..8a5838f1d1 100644
--- a/src/playsim/a_dynlight.cpp
+++ b/src/playsim/a_dynlight.cpp
@@ -850,6 +850,7 @@ int AttachLightDef(AActor *self, int _lightid, int _lightname)
 		auto userlight = self->UserLights[FindUserLight(self, lightid, true)];
 		userlight->CopyFrom(*LightDefaults[lightdef]);
 		self->flags8 |= MF8_RECREATELIGHTS;
+		self->Level->flags3 |= LEVEL3_LIGHTCREATED;
 		return 1;
 	}
 	return 0;
@@ -894,6 +895,7 @@ int AttachLightDirect(AActor *self, int _lightid, int type, int color, int radiu
 		userlight->UnsetSpotPitch();
 	}
 	self->flags8 |= MF8_RECREATELIGHTS;
+	self->Level->flags3 |= LEVEL3_LIGHTCREATED;
 	return 1;
 }
 
@@ -931,6 +933,7 @@ int RemoveLight(AActor *self, int _lightid)
 		delete self->UserLights[userlight];
 		self->UserLights.Delete(userlight);
 		self->flags8 |= MF8_RECREATELIGHTS;
+		self->Level->flags3 |= LEVEL3_LIGHTCREATED;
 		return 1;
 	}
 	return 0;
diff --git a/src/playsim/dthinker.cpp b/src/playsim/dthinker.cpp
index 75c75e7895..013ea0829a 100644
--- a/src/playsim/dthinker.cpp
+++ b/src/playsim/dthinker.cpp
@@ -144,8 +144,9 @@ void FThinkerCollection::RunThinkers(FLevelLocals *Level)
 			}
 		} while (count != 0);
 
-		if (Level->HasDynamicLights)
+		if (Level->lights || (Level->flags3 & LEVEL3_LIGHTCREATED))
 		{
+			Level->flags3 &= ~LEVEL3_LIGHTCREATED;
 			recreateLights();
 			for (auto light = Level->lights; light;)
 			{
@@ -174,8 +175,9 @@ void FThinkerCollection::RunThinkers(FLevelLocals *Level)
 			}
 		} while (count != 0);
 
-		if (Level->lights && Level->HasDynamicLights)
+		if (Level->lights || (Level->flags3 & LEVEL3_LIGHTCREATED))
 		{
+			Level->flags3 &= ~LEVEL3_LIGHTCREATED;
 			recreateLights();
 			// Also profile the internal dynamic lights, even though they are not implemented as thinkers.
 			auto &prof = Profiles[NAME_InternalDynamicLight];
diff --git a/src/playsim/p_mobj.cpp b/src/playsim/p_mobj.cpp
index cba3950d7b..39ec58a47d 100644
--- a/src/playsim/p_mobj.cpp
+++ b/src/playsim/p_mobj.cpp
@@ -584,7 +584,11 @@ bool AActor::SetState (FState *newstate, bool nofunction)
 		newstate = newstate->GetNextState();
 	} while (tics == 0);
 
-	flags8 |= MF8_RECREATELIGHTS;
+	if (GetInfo()->LightAssociations.Size())
+	{
+		flags8 |= MF8_RECREATELIGHTS;
+		Level->flags3 |= LEVEL3_LIGHTCREATED;
+	}
 	return true;
 }
 
@@ -4799,7 +4803,11 @@ void AActor::PostBeginPlay ()
 {
 	PrevAngles = Angles;
 	flags7 |= MF7_HANDLENODELAY;
-	flags8 |= MF8_RECREATELIGHTS;
+	if (GetInfo()->LightAssociations.Size())
+	{
+		flags8 |= MF8_RECREATELIGHTS;
+		Level->flags3 |= LEVEL3_LIGHTCREATED;
+	}
 }
 
 void AActor::CallPostBeginPlay()
diff --git a/wadsrc/static/zscript/constants.zs b/wadsrc/static/zscript/constants.zs
index c288f2e450..a3cf305195 100644
--- a/wadsrc/static/zscript/constants.zs
+++ b/wadsrc/static/zscript/constants.zs
@@ -1333,6 +1333,15 @@ enum ELevelFlags
 	LEVEL3_HIDEAUTHORNAME		= 0x00000100,
 	LEVEL3_PROPERMONSTERFALLINGDAMAGE	= 0x00000200,	// Properly apply falling damage to the monsters
 	LEVEL3_SKYBOXAO				= 0x00000400,	// Apply SSAO to sector skies
+	LEVEL3_E1M8SPECIAL			= 0x00000800,
+	LEVEL3_E2M8SPECIAL			= 0x00001000,
+	LEVEL3_E3M8SPECIAL			= 0x00002000,
+	LEVEL3_E4M8SPECIAL			= 0x00004000,
+	LEVEL3_E4M6SPECIAL			= 0x00008000,
+	LEVEL3_NOSHADOWMAP			= 0x00010000,	// disables shadowmaps for a given level.
+	LEVEL3_AVOIDMELEE			= 0x00020000,	// global flag needed for proper MBF support.
+	LEVEL3_NOJUMPDOWN			= 0x00040000,	// only for MBF21. Inverse of MBF's dog_jumping flag.
+	LEVEL3_LIGHTCREATED			= 0x00080000,	// a light had been created in the last frame
 };
 
 // [RH] Compatibility flags.