From 4af5ea25c12d2f2be196b628334af9aef474352c Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@users.noreply.github.com>
Date: Tue, 29 Jan 2019 20:09:06 +0100
Subject: [PATCH] - change per-level attenuation of dynamic lights for each
 viewpoint.

To avoid unnecessary work, the current state is tracked.
---
 src/g_level.cpp               |  2 --
 src/g_shared/a_dynlight.h     |  2 +-
 src/gl/renderer/gl_scene.cpp  |  4 ++++
 src/r_data/a_dynlightdata.cpp | 13 +++++++++----
 src/r_data/gldefs.cpp         |  2 ++
 5 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/src/g_level.cpp b/src/g_level.cpp
index 5491367ad..3a29c2098 100644
--- a/src/g_level.cpp
+++ b/src/g_level.cpp
@@ -1552,8 +1552,6 @@ void FLevelLocals::Init()
 	brightfog = info->brightfog < 0? gl_brightfog : !!info->brightfog;
 	lightadditivesurfaces = info->lightadditivesurfaces < 0 ? gl_lightadditivesurfaces : !!info->lightadditivesurfaces;
 	notexturefill = info->notexturefill < 0 ? gl_notexturefill : !!info->notexturefill;
-
-	FLightDefaults::SetAttenuationForLevel();
 }
 
 //==========================================================================
diff --git a/src/g_shared/a_dynlight.h b/src/g_shared/a_dynlight.h
index 25d6a3477..77c971942 100644
--- a/src/g_shared/a_dynlight.h
+++ b/src/g_shared/a_dynlight.h
@@ -76,7 +76,7 @@ public:
 	void SetSpot(bool spot) { if (spot) m_lightFlags |= LF_SPOT; else m_lightFlags &= ~LF_SPOT; }
 	void SetSpotInnerAngle(double angle) { m_spotInnerAngle = angle; }
 	void SetSpotOuterAngle(double angle) { m_spotOuterAngle = angle; }
-	static void SetAttenuationForLevel();
+	static void SetAttenuationForLevel(bool);
 
 	void OrderIntensities()
 	{
diff --git a/src/gl/renderer/gl_scene.cpp b/src/gl/renderer/gl_scene.cpp
index 8e6475c96..c62203be9 100644
--- a/src/gl/renderer/gl_scene.cpp
+++ b/src/gl/renderer/gl_scene.cpp
@@ -156,6 +156,10 @@ sector_t * FGLRenderer::RenderViewpoint (FRenderViewpoint &mainvp, AActor * came
 	if (mainview && toscreen)
 		UpdateShadowMap();
 
+	// Update the attenuation flag of all light defaults for each viewpoint.
+	// This function will only do something if the setting differs.
+	FLightDefaults::SetAttenuationForLevel(!!(camera->Level->flags3 & LEVEL3_ATTENUATE));
+
     // Render (potentially) multiple views for stereo 3d
 	// Fixme. The view offsetting should be done with a static table and not require setup of the entire render state for the mode.
 	auto vrmode = VRMode::GetVRMode(mainview && toscreen);
diff --git a/src/r_data/a_dynlightdata.cpp b/src/r_data/a_dynlightdata.cpp
index f0b66f972..e6ed0c10b 100644
--- a/src/r_data/a_dynlightdata.cpp
+++ b/src/r_data/a_dynlightdata.cpp
@@ -55,6 +55,7 @@ inline PClassActor * GetRealType(PClassActor * ti)
 }
 
 TDeletingArray<FLightDefaults *> LightDefaults;
+int AttenuationIsSet = -1;
 
 //-----------------------------------------------------------------------------
 //
@@ -101,14 +102,18 @@ void FLightDefaults::ApplyProperties(FDynamicLight * light) const
 	light->SetOffset(m_Pos);	// this must be the last thing to do.
 }
 
-void FLightDefaults::SetAttenuationForLevel()
+void FLightDefaults::SetAttenuationForLevel(bool yes)
 {
-	for (auto ldef : LightDefaults)
+	if (AttenuationIsSet != int(yes))
 	{
-		if (ldef->m_attenuate == -1)
+		for (auto ldef : LightDefaults)
 		{
-			if (level.flags3 & LEVEL3_ATTENUATE)  ldef->m_lightFlags |= LF_ATTENUATE; else ldef->m_lightFlags &= ~LF_ATTENUATE;
+			if (ldef->m_attenuate == -1)
+			{
+				if (yes)  ldef->m_lightFlags |= LF_ATTENUATE; else ldef->m_lightFlags &= ~LF_ATTENUATE;
+			}
 		}
+		AttenuationIsSet = yes;
 	}
 }
 
diff --git a/src/r_data/gldefs.cpp b/src/r_data/gldefs.cpp
index 054e299cd..e853ed6e4 100644
--- a/src/r_data/gldefs.cpp
+++ b/src/r_data/gldefs.cpp
@@ -53,6 +53,7 @@ void InitializeActorLights(TArray<FLightAssociation> &LightAssociations);
 
 TArray<UserShaderDesc> usershaders;
 extern TDeletingArray<FLightDefaults *> LightDefaults;
+extern int AttenuationIsSet;
 
 
 //-----------------------------------------------------------------------------
@@ -1777,6 +1778,7 @@ void ParseGLDefs()
 	const char *defsLump = NULL;
 
 	LightDefaults.DeleteAndClear();
+	AttenuationIsSet = -1;
 	//gl_DestroyUserShaders(); function says 'todo'
 	switch (gameinfo.gametype)
 	{