From acb95056066e1277014acbc19a9b4e73ec69d566 Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@users.noreply.github.com>
Date: Sat, 20 Oct 2018 10:33:26 +0200
Subject: [PATCH] - fixed cherry-picked commit so that modern OpenGL can still
 do the light setup in the render pass.

---
 src/gl/scene/gl_flats.cpp         | 13 ++++++++++---
 src/hwrenderer/scene/hw_flats.cpp |  9 ++++++---
 src/v_video.h                     |  1 +
 3 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/src/gl/scene/gl_flats.cpp b/src/gl/scene/gl_flats.cpp
index ca18a589ad..1d878bc64c 100644
--- a/src/gl/scene/gl_flats.cpp
+++ b/src/gl/scene/gl_flats.cpp
@@ -112,7 +112,14 @@ void FDrawInfo::DrawSubsectors(GLFlat *flat, int pass, bool processlights, bool
 	gl_RenderState.Apply();
 	auto iboindex = flat->iboindex;
 
-	if (processlights) gl_RenderState.ApplyLightIndex(flat->dynlightindex);
+	if (processlights) 
+	{
+		if (screen->hwcaps & RFL_BUFFER_STORAGE)
+		{
+			flat->SetupLights(this, flat->sector->lighthead, lightdata, flat->sector->PortalGroup);
+		}
+		gl_RenderState.ApplyLightIndex(flat->dynlightindex);
+	}
 
 	if (iboindex >= 0)
 	{
@@ -215,13 +222,13 @@ void FDrawInfo::DrawFlat(GLFlat *flat, int pass, bool trans)	// trans only has m
 		{
 			gl_RenderState.SetMaterial(flat->gltexture, CLAMP_NONE, 0, -1, false);
 			gl_RenderState.SetPlaneTextureRotation(&plane, flat->gltexture);
-			DrawSubsectors(flat, pass, processLights && (gl.lightmethod == LM_DIRECT || flat->dynlightindex > -1), false);
+			DrawSubsectors(flat, pass, processLights, false);
 			gl_RenderState.EnableTextureMatrix(false);
 		}
 		else
 		{
 			gl_RenderState.SetMaterial(flat->gltexture, CLAMP_XY, 0, -1, false);
-			DrawSkyboxSector(flat, pass, processLights && (gl.lightmethod == LM_DIRECT || flat->dynlightindex > -1));
+			DrawSkyboxSector(flat, pass, processLights);
 		}
 		gl_RenderState.SetObjectColor(0xffffffff);
 		break;
diff --git a/src/hwrenderer/scene/hw_flats.cpp b/src/hwrenderer/scene/hw_flats.cpp
index 33937f3909..0973b03146 100644
--- a/src/hwrenderer/scene/hw_flats.cpp
+++ b/src/hwrenderer/scene/hw_flats.cpp
@@ -139,6 +139,7 @@ void GLFlat::SetupLights(HWDrawInfo *di, FLightNode * node, FDynLightData &light
 {
 	Plane p;
 
+	lightdata.Clear();
 	if (renderstyle == STYLE_Add && !level.lightadditivesurfaces)
 	{
 		dynlightindex = -1;
@@ -182,14 +183,16 @@ void GLFlat::SetupLights(HWDrawInfo *di, FLightNode * node, FDynLightData &light
 
 inline void GLFlat::PutFlat(HWDrawInfo *di, bool fog)
 {
-
 	if (di->isFullbrightScene())
 	{
 		Colormap.Clear();
 	}
-	else if (level.HasDynamicLights && gltexture != nullptr)
+	else if (!(screen->hwcaps & RFL_BUFFER_STORAGE))
 	{
-		SetupLights(di, sector->lighthead, lightdata, sector->PortalGroup);
+		if (level.HasDynamicLights && gltexture != nullptr)
+		{
+			SetupLights(di, sector->lighthead, lightdata, sector->PortalGroup);
+		}
 	}
 	di->AddFlat(this, fog);
 }
diff --git a/src/v_video.h b/src/v_video.h
index 72ae6e0a5c..6908dfd575 100644
--- a/src/v_video.h
+++ b/src/v_video.h
@@ -57,6 +57,7 @@ enum EHWCaps
 
 	RFL_SHADER_STORAGE_BUFFER = 4,
 	RFL_BUFFER_STORAGE = 8,
+	RFL_NO_LIGHT_PREGENERATE = 16,	// delays dynamic light creation until the render pass. With modern OpenGL this is faster because it can make use of the CPU while the GPU is rendering.
 
 	RFL_NO_CLIP_PLANES = 32,