From cb758f6daba05af7e625bf1ecd4565f5f83711de Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@users.noreply.github.com>
Date: Mon, 13 Feb 2017 22:17:15 +0100
Subject: [PATCH] - added a 'nolightfade' MAPINFO option which disables light
 diminishing in OpenGL. Note that this only works for light modes 0-3. Modes 4
 and 8 use special light math that would not work if such a setting was
 forced.

---
 src/gl/data/gl_data.cpp          | 19 +++++++++++++++++++
 src/gl/data/gl_data.h            |  1 +
 src/gl/renderer/gl_lightdata.cpp |  2 +-
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/gl/data/gl_data.cpp b/src/gl/data/gl_data.cpp
index bb73ad3ae..bd185f76f 100644
--- a/src/gl/data/gl_data.cpp
+++ b/src/gl/data/gl_data.cpp
@@ -212,6 +212,7 @@ struct FGLROptions : public FOptionalMapinfoData
 		lightmode = -1;
 		attenuate = -1;
 		nocoloredspritelighting = -1;
+		nolightfade = false;
 		notexturefill = -1;
 		skyrotatevector = FVector3(0,0,1);
 		skyrotatevector2 = FVector3(0,0,1);
@@ -228,6 +229,7 @@ struct FGLROptions : public FOptionalMapinfoData
 		newopt->lightmode = lightmode;
 		newopt->attenuate = attenuate;
 		newopt->nocoloredspritelighting = nocoloredspritelighting;
+		newopt->nolightfade = nolightfade;
 		newopt->notexturefill = notexturefill;
 		newopt->skyrotatevector = skyrotatevector;
 		newopt->skyrotatevector2 = skyrotatevector2;
@@ -244,6 +246,7 @@ struct FGLROptions : public FOptionalMapinfoData
 	int8_t		lightadditivesurfaces;
 	int8_t		nocoloredspritelighting;
 	int8_t		notexturefill;
+	bool		nolightfade;
 	FVector3	skyrotatevector;
 	FVector3	skyrotatevector2;
 	float		pixelstretch;
@@ -303,6 +306,20 @@ DEFINE_MAP_OPTION(nocoloredspritelighting, false)
 	}
 }
 
+DEFINE_MAP_OPTION(nolightfade, false)
+{
+	FGLROptions *opt = info->GetOptData<FGLROptions>("gl_renderer");
+	if (parse.CheckAssign())
+	{
+		parse.sc.MustGetNumber();
+		opt->nolightfade = !!parse.sc.Number;
+	}
+	else
+	{
+		opt->nolightfade = true;
+	}
+}
+
 DEFINE_MAP_OPTION(notexturefill, false)
 {
 	FGLROptions *opt = info->GetOptData<FGLROptions>("gl_renderer");
@@ -423,6 +440,7 @@ void InitGLRMapinfoData()
 		glset.skyrotatevector = opt->skyrotatevector;
 		glset.skyrotatevector2 = opt->skyrotatevector2;
 		glset.pixelstretch = opt->pixelstretch;
+		glset.nolightfade = opt->nolightfade;
 	}
 	else
 	{
@@ -436,6 +454,7 @@ void InitGLRMapinfoData()
 		glset.skyrotatevector = FVector3(0, 0, 1);
 		glset.skyrotatevector2 = FVector3(0, 0, 1);
 		glset.pixelstretch = 1.2f;
+		glset.nolightfade = false;
 	}
 	ResetOpts();
 }
diff --git a/src/gl/data/gl_data.h b/src/gl/data/gl_data.h
index d5bdeb46a..cf79fe138 100644
--- a/src/gl/data/gl_data.h
+++ b/src/gl/data/gl_data.h
@@ -10,6 +10,7 @@ struct GLRenderSettings
 
 	SBYTE lightmode;
 	bool nocoloredspritelighting;
+	bool nolightfade;
 	bool notexturefill;
 	bool brightfog;
 	bool lightadditivesurfaces;
diff --git a/src/gl/renderer/gl_lightdata.cpp b/src/gl/renderer/gl_lightdata.cpp
index b4912f825..c017453bd 100644
--- a/src/gl/renderer/gl_lightdata.cpp
+++ b/src/gl/renderer/gl_lightdata.cpp
@@ -312,7 +312,7 @@ float gl_GetFogDensity(int lightlevel, PalEntry fogcolor, int sectorfogdensity)
 	else if ((fogcolor.d & 0xffffff) == 0)
 	{
 		// case 2: black fog
-		if (glset.lightmode != 8)
+		if (glset.lightmode != 8 && !glset.nolightfade)
 		{
 			density = distfogtable[glset.lightmode != 0][gl_ClampLight(lightlevel)];
 		}