From 918e9e9b0d1e6d5162ef885d408a319b0c793ebd Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@users.noreply.github.com>
Date: Fri, 17 Sep 2021 00:25:28 +0200
Subject: [PATCH] - fixed texture clamping for elements that are partially
 behind a slope.

This is mainly mid textures on linedefs and decals.
---
 src/common/engine/renderstyle.h                  |  6 ++++--
 .../rendering/hwrenderer/data/hw_renderstate.h   |  3 ++-
 src/rendering/hwrenderer/scene/hw_decal.cpp      |  2 +-
 src/rendering/hwrenderer/scene/hw_walls.cpp      | 10 +++++-----
 wadsrc/static/shaders/glsl/main.fp               | 16 ++++++++--------
 5 files changed, 20 insertions(+), 17 deletions(-)

diff --git a/src/common/engine/renderstyle.h b/src/common/engine/renderstyle.h
index 70ad5d561..7d0a7b877 100644
--- a/src/common/engine/renderstyle.h
+++ b/src/common/engine/renderstyle.h
@@ -51,10 +51,12 @@ enum ETexMode
 	TM_OPAQUE,			// (r, g, b, 1)
 	TM_INVERSE,			// (1-r, 1-g, 1-b, a)
 	TM_ALPHATEXTURE,		// (1, 1, 1, r)
-	TM_CLAMPY,			// (r, g, b, (t >= 0.0 && t <= 1.0)? a:0)
-	TM_INVERTOPAQUE,	// (1-r, 1-g, 1-b, 1)
+	TM_INVERTOPAQUE = 6,	// (1-r, 1-g, 1-b, 1)
 	TM_FOGLAYER,		// (renders a fog layer in the shape of the active texture)
 	TM_FIXEDCOLORMAP = TM_FOGLAYER,	// repurposes the objectcolor uniforms to render a fixed colormap range. (Same constant because they cannot be used in the same context.
+
+	TM_CLAMPY = 0x1000,			// (r, g, b, (t >= 0.0 && t <= 1.0)? a:0)
+
 };
 
 // Legacy render styles
diff --git a/src/common/rendering/hwrenderer/data/hw_renderstate.h b/src/common/rendering/hwrenderer/data/hw_renderstate.h
index 4751cba0b..e6c63ba44 100644
--- a/src/common/rendering/hwrenderer/data/hw_renderstate.h
+++ b/src/common/rendering/hwrenderer/data/hw_renderstate.h
@@ -342,7 +342,7 @@ public:
 		mTextureMode = mode;
 	}
 
-	void SetTextureMode(FRenderStyle style)
+	void SetTextureMode(FRenderStyle style, bool clampy = false)
 	{
 		if (style.Flags & STYLEF_RedIsAlpha)
 		{
@@ -356,6 +356,7 @@ public:
 		{
 			SetTextureMode(TM_INVERSE);
 		}
+		if (clampy) mTextureMode |= TM_CLAMPY;
 	}
 
 	int GetTextureMode()
diff --git a/src/rendering/hwrenderer/scene/hw_decal.cpp b/src/rendering/hwrenderer/scene/hw_decal.cpp
index ac1b34e85..04fe5d4a1 100644
--- a/src/rendering/hwrenderer/scene/hw_decal.cpp
+++ b/src/rendering/hwrenderer/scene/hw_decal.cpp
@@ -61,7 +61,7 @@ void HWDecal::DrawDecal(HWDrawInfo *di, FRenderState &state)
 	state.SetObjectColor(DecalColor);
 
 	state.SetLightIndex(dynlightindex);
-	state.SetTextureMode(decal->RenderStyle);
+	state.SetTextureMode(decal->RenderStyle, true);
 	state.SetRenderStyle(decal->RenderStyle);
 	state.SetMaterial(texture, UF_Sprite, 0, CLAMP_XY, decal->Translation, -1);
 
diff --git a/src/rendering/hwrenderer/scene/hw_walls.cpp b/src/rendering/hwrenderer/scene/hw_walls.cpp
index 4abf8d33d..5df353550 100644
--- a/src/rendering/hwrenderer/scene/hw_walls.cpp
+++ b/src/rendering/hwrenderer/scene/hw_walls.cpp
@@ -208,13 +208,13 @@ void HWWall::RenderTexturedWall(HWDrawInfo *di, FRenderState &state, int rflags)
 	}
 #endif
 
+	if (flags & HWWall::HWF_CLAMPY && (type == RENDERWALL_M2S || type == RENDERWALL_M2SNF))
+	{
+		state.SetTextureMode(tmode | TM_CLAMPY);
+	}
 
 	if (type == RENDERWALL_M2SNF)
 	{
-		if (flags & HWWall::HWF_CLAMPY)
-		{
-			if (tmode == TM_NORMAL) state.SetTextureMode(TM_CLAMPY);
-		}
 		di->SetFog(state, 255, 0, di->isFullbrightScene(), nullptr, false);
 	}
 	if (type != RENDERWALL_COLOR && seg->sidedef != nullptr)
@@ -1933,7 +1933,7 @@ void HWWall::Process(HWDrawInfo *di, seg_t *seg, sector_t * frontsector, sector_
 	sector_t * segback;
 
 #ifdef _DEBUG
-	if (seg->linedef->Index() == 14454)
+	if (seg->linedef->Index() == 759)
 	{
 		int a = 0;
 	}
diff --git a/wadsrc/static/shaders/glsl/main.fp b/wadsrc/static/shaders/glsl/main.fp
index 63b92bd7e..90ad8cbee 100644
--- a/wadsrc/static/shaders/glsl/main.fp
+++ b/wadsrc/static/shaders/glsl/main.fp
@@ -166,7 +166,7 @@ vec4 getTexel(vec2 st)
 	//
 	// Apply texture modes
 	//
-	switch (uTextureMode & 0xffff)
+	switch (uTextureMode & 0xfff)
 	{
 		case 1:	// TM_STENCIL
 			texel.rgb = vec3(1.0,1.0,1.0);
@@ -187,13 +187,6 @@ vec4 getTexel(vec2 st)
 			break;
 		}
 			
-		case 5:	// TM_CLAMPY
-			if (st.t < 0.0 || st.t > 1.0)
-			{
-				texel.a = 0.0;
-			}
-			break;
-			
 		case 6: // TM_OPAQUEINVERSE
 			texel = vec4(1.0-texel.r, 1.0-texel.b, 1.0-texel.g, 1.0);
 			break;
@@ -202,6 +195,13 @@ vec4 getTexel(vec2 st)
 			return texel;
 
 	}
+	if ((uTextureMode & 0x1000) != 0) // TM_CLAMPY
+	{
+		if (st.t < 0.0 || st.t > 1.0)
+		{
+			texel.a = 0.0;
+		}
+	}
 	
 	// Apply the texture modification colors.
 	int blendflags = int(uTextureAddColor.a);	// this alpha is unused otherwise