From 51baa7d137486bf07c40017e471aa4340c2857e1 Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@zdoom.fake>
Date: Thu, 5 May 2016 11:32:21 +0200
Subject: [PATCH] - added code to calculate light texture coordinates on walls.

---
 src/gl/compatibility/gl_20.cpp | 58 ++++++++++++++++++++++++++++++++--
 src/gl/scene/gl_wall.h         |  3 +-
 2 files changed, 56 insertions(+), 5 deletions(-)

diff --git a/src/gl/compatibility/gl_20.cpp b/src/gl/compatibility/gl_20.cpp
index 5c7c983d3..96cd88fd8 100644
--- a/src/gl/compatibility/gl_20.cpp
+++ b/src/gl/compatibility/gl_20.cpp
@@ -379,7 +379,7 @@ void FRenderState::DrawColormapOverlay()
 //==========================================================================
 
 bool gl_SetupLight(int group, Plane & p, ADynamicLight * light, Vector & nearPt, Vector & up, Vector & right,
-	float & scale, int desaturation, bool checkside, bool forceadditive)
+	float & scale, int desaturation, bool checkside, bool additive)
 {
 	Vector fn, pos;
 
@@ -416,7 +416,7 @@ bool gl_SetupLight(int group, Plane & p, ADynamicLight * light, Vector & nearPt,
 #endif
 
 	float cs = 1.0f - (dist / radius);
-	if (gl_lights_additive || light->flags4&MF4_ADDITIVE || forceadditive) cs *= 0.2f;	// otherwise the light gets too strong.
+	if (additive) cs *= 0.2f;	// otherwise the light gets too strong.
 	float r = light->GetRed() / 255.0f * cs * gl_lights_intensity;
 	float g = light->GetGreen() / 255.0f * cs * gl_lights_intensity;
 	float b = light->GetBlue() / 255.0f * cs * gl_lights_intensity;
@@ -613,7 +613,7 @@ void GLFlat::DrawSubsectorLights(subsector_t * sub, int pass)
 		}
 
 		p.Set(plane.plane);
-		if (!gl_SetupLight(sub->sector->PortalGroup, p, light, nearPt, up, right, scale, CM_DEFAULT, false, foggy))
+		if (!gl_SetupLight(sub->sector->PortalGroup, p, light, nearPt, up, right, scale, CM_DEFAULT, false, pass == GLPASS_LIGHTTEX_ADDITIVE))
 		{
 			node = node->nextLight;
 			continue;
@@ -681,6 +681,58 @@ void GLFlat::DrawLightsCompat(int pass)
 }
 
 
+//==========================================================================
+//
+// Sets up the texture coordinates for one light to be rendered
+//
+//==========================================================================
+bool GLWall::PrepareLight(texcoord * tcs, ADynamicLight * light, int pass)
+{
+	float vtx[] = { glseg.x1,zbottom[0],glseg.y1, glseg.x1,ztop[0],glseg.y1, glseg.x2,ztop[1],glseg.y2, glseg.x2,zbottom[1],glseg.y2 };
+	Plane p;
+	Vector nearPt, up, right;
+	float scale;
+
+	p.Init(vtx, 4);
+
+	if (!p.ValidNormal())
+	{
+		return false;
+	}
+
+	if (!gl_SetupLight(seg->frontsector->PortalGroup, p, light, nearPt, up, right, scale, CM_DEFAULT, true, pass == GLPASS_LIGHTTEX_ADDITIVE))
+	{
+		return false;
+	}
+
+	if (tcs != NULL)
+	{
+		Vector t1;
+		int outcnt[4] = { 0,0,0,0 };
+
+		for (int i = 0; i<4; i++)
+		{
+			t1.Set(&vtx[i * 3]);
+			Vector nearToVert = t1 - nearPt;
+			tcs[i].u = (nearToVert.Dot(right) * scale) + 0.5f;
+			tcs[i].v = (nearToVert.Dot(up) * scale) + 0.5f;
+
+			// quick check whether the light touches this polygon
+			if (tcs[i].u<0) outcnt[0]++;
+			if (tcs[i].u>1) outcnt[1]++;
+			if (tcs[i].v<0) outcnt[2]++;
+			if (tcs[i].v>1) outcnt[3]++;
+
+		}
+		// The light doesn't touch this polygon
+		if (outcnt[0] == 4 || outcnt[1] == 4 || outcnt[2] == 4 || outcnt[3] == 4) return false;
+	}
+
+	draw_dlight++;
+	return true;
+}
+
+
 //==========================================================================
 //
 //
diff --git a/src/gl/scene/gl_wall.h b/src/gl/scene/gl_wall.h
index 3bdcbd6ce..cfd8ae361 100644
--- a/src/gl/scene/gl_wall.h
+++ b/src/gl/scene/gl_wall.h
@@ -183,7 +183,7 @@ private:
 	void SplitWall(sector_t * frontsector, bool translucent);
 
 	void SetupLights();
-	bool PrepareLight(texcoord * tcs, ADynamicLight * light);
+	bool PrepareLight(texcoord * tcs, ADynamicLight * light, int pass);
 	void RenderWall(int textured, unsigned int *store = NULL);
 	void RenderTextured(int rflags);
 
@@ -288,7 +288,6 @@ public:
 	GLSectorPlane plane;
 	int lightlevel;
 	bool stack;
-	bool foggy;
 	bool ceiling;
 	BYTE renderflags;
 	int vboindex;