From 468273658521ba20335a43da4e2c1d6ceaf5ceef Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@zdoom.fake>
Date: Sun, 21 Sep 2014 11:08:17 +0200
Subject: [PATCH] - fixed: non-tiled mid textures on a fog boundary require
 some special clamping to be performed in the shader.

---
 src/gl/renderer/gl_renderstate.h   |  5 +++++
 src/gl/scene/gl_walls_draw.cpp     | 24 +++++++++++++++++++++---
 src/gl/system/gl_interface.h       |  1 +
 wadsrc/static/shaders/glsl/main.fp |  7 +++++++
 4 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/src/gl/renderer/gl_renderstate.h b/src/gl/renderer/gl_renderstate.h
index e0f5406dd..b30d7920f 100644
--- a/src/gl/renderer/gl_renderstate.h
+++ b/src/gl/renderer/gl_renderstate.h
@@ -177,6 +177,11 @@ public:
 		mTextureMode = mode;
 	}
 
+	int GetTextureMode()
+	{
+		return mTextureMode;
+	}
+
 	void EnableTexture(bool on)
 	{
 		mTextureEnabled = on;
diff --git a/src/gl/scene/gl_walls_draw.cpp b/src/gl/scene/gl_walls_draw.cpp
index 1644c6605..801bebcc5 100644
--- a/src/gl/scene/gl_walls_draw.cpp
+++ b/src/gl/scene/gl_walls_draw.cpp
@@ -338,10 +338,18 @@ void GLWall::RenderTranslucentWall()
 		gl_RenderState.EnableTexture(false);
 		extra = 0;
 	}
+	int tmode = gl_RenderState.GetTextureMode();
 
 	gl_SetColor(lightlevel, extra, Colormap, fabsf(alpha));
 	if (type!=RENDERWALL_M2SNF) gl_SetFog(lightlevel, extra, &Colormap, isadditive);
-	else gl_SetFog(255, 0, NULL, false);
+	else
+	{
+		if (flags & GLT_CLAMPY)
+		{
+			if (tmode == TM_MODULATE) gl_RenderState.SetTextureMode(TM_CLAMPY);
+		}
+		gl_SetFog(255, 0, NULL, false);
+	}
 
 	RenderWall(RWF_TEXTURED|RWF_NOSPLIT);
 
@@ -353,6 +361,7 @@ void GLWall::RenderTranslucentWall()
 		gl_RenderState.EnableTexture(true);
 	}
 	gl_RenderState.EnableGlow(false);
+	gl_RenderState.SetTextureMode(tmode);
 }
 
 //==========================================================================
@@ -363,6 +372,7 @@ void GLWall::RenderTranslucentWall()
 void GLWall::Draw(int pass)
 {
 	int rel;
+	int tmode;
 
 #ifdef _DEBUG
 	if (seg->linedef-lines==879)
@@ -384,13 +394,21 @@ void GLWall::Draw(int pass)
 	case GLPASS_PLAIN:
 		rel = rellight + getExtraLight();
 		gl_SetColor(lightlevel, rel, Colormap,1.0f);
+		tmode = gl_RenderState.GetTextureMode();
 		if (type!=RENDERWALL_M2SNF) gl_SetFog(lightlevel, rel, &Colormap, false);
-		else gl_SetFog(255, 0, NULL, false);
-
+		else
+		{
+			if (flags & GLT_CLAMPY)
+			{
+				if (tmode == TM_MODULATE) gl_RenderState.SetTextureMode(TM_CLAMPY);
+			}
+			gl_SetFog(255, 0, NULL, false);
+		}
 		gl_RenderState.EnableGlow(!!(flags & GLWF_GLOW));
 		gl_RenderState.SetMaterial(gltexture, flags & 3, false, -1, false);
 		RenderWall(RWF_TEXTURED|RWF_GLOW);
 		gl_RenderState.EnableGlow(false);
+		gl_RenderState.SetTextureMode(tmode);
 		break;
 
 	case GLPASS_TRANSLUCENT:
diff --git a/src/gl/system/gl_interface.h b/src/gl/system/gl_interface.h
index 2d2e26d51..6f2fb2bfc 100644
--- a/src/gl/system/gl_interface.h
+++ b/src/gl/system/gl_interface.h
@@ -20,6 +20,7 @@ enum TexMode
 	TM_OPAQUE,			// (r, g, b, 1)
 	TM_INVERSE,			// (1-r, 1-g, 1-b, a)
 	TM_REDTOALPHA,		// (1, 1, 1, r)
+	TM_CLAMPY,			// (r, g, b, (t >= 0.0 && t <= 1.0)? a:0)
 };
 
 struct RenderContext
diff --git a/wadsrc/static/shaders/glsl/main.fp b/wadsrc/static/shaders/glsl/main.fp
index 6fa304f92..e7421106b 100644
--- a/wadsrc/static/shaders/glsl/main.fp
+++ b/wadsrc/static/shaders/glsl/main.fp
@@ -75,6 +75,13 @@ vec4 getTexel(vec2 st)
 		case 4:	// TM_REDTOALPHA
 			texel = vec4(1.0, 1.0, 1.0, texel.r);
 			break;
+			
+		case 5:	// TM_CLAMPY
+			if (st.t < 0.0 || st.t > 1.0)
+			{
+				texel.a = 0.0;
+			}
+			break;
 	}
 	texel *= uObjectColor;