From b9ca3c85f8cde4b145a82029307728577a07aed6 Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@zdoom.fake>
Date: Thu, 8 Sep 2016 12:18:09 +0200
Subject: [PATCH] - fixed: translucency detection in multipatch textures did
 not work. - fixed: The flat drawer never checked if a texture had translucent
 parts.

---
 src/gl/scene/gl_flats.cpp          | 19 ++++++++++++++++++-
 src/textures/bitmap.h              |  2 +-
 src/textures/multipatchtexture.cpp |  5 +++--
 3 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/src/gl/scene/gl_flats.cpp b/src/gl/scene/gl_flats.cpp
index 9e9a73e5d..48ad30786 100644
--- a/src/gl/scene/gl_flats.cpp
+++ b/src/gl/scene/gl_flats.cpp
@@ -419,15 +419,17 @@ void GLFlat::Draw(int pass, bool trans)	// trans only has meaning for GLPASS_LIG
 		if (renderstyle==STYLE_Add) gl_RenderState.BlendFunc(GL_SRC_ALPHA, GL_ONE);
 		gl_SetColor(lightlevel, rel, Colormap, alpha);
 		gl_SetFog(lightlevel, rel, &Colormap, false);
-		gl_RenderState.AlphaFunc(GL_GEQUAL, gl_mask_threshold);
 		if (!gltexture)	
 		{
+			gl_RenderState.AlphaFunc(GL_GEQUAL, 0.f);
 			gl_RenderState.EnableTexture(false);
 			DrawSubsectors(pass, false, true);
 			gl_RenderState.EnableTexture(true);
 		}
 		else 
 		{
+			if (!gltexture->GetTransparent()) gl_RenderState.AlphaFunc(GL_GEQUAL, gl_mask_threshold);
+			else gl_RenderState.AlphaFunc(GL_GEQUAL, 0.f);
 			gl_RenderState.SetMaterial(gltexture, CLAMP_NONE, 0, -1, false);
 			gl_SetPlaneTextureRotation(&plane, gltexture);
 			DrawSubsectors(pass, !gl.legacyMode, true);
@@ -477,6 +479,21 @@ inline void GLFlat::PutFlat(bool fog)
 		// translucent 3D floors go into the regular translucent list, translucent portals go into the translucent border list.
 		list = (renderflags&SSRF_RENDER3DPLANES) ? GLDL_TRANSLUCENT : GLDL_TRANSLUCENTBORDER;
 	}
+	else if (gltexture->GetTransparent())
+	{
+		if (stack)
+		{
+			list = GLDL_TRANSLUCENTBORDER;
+		}
+		else if ((renderflags&SSRF_RENDER3DPLANES) && !plane.plane.isSlope())
+		{
+			list = GLDL_TRANSLUCENT;
+		} 
+		else 
+		{
+			list = GLDL_PLAINFLATS;
+		}
+	}
 	else
 	{
 		bool masked = gltexture->isMasked() && ((renderflags&SSRF_RENDER3DPLANES) || stack);
diff --git a/src/textures/bitmap.h b/src/textures/bitmap.h
index 27d3c0b4b..a27d1ff98 100644
--- a/src/textures/bitmap.h
+++ b/src/textures/bitmap.h
@@ -380,7 +380,7 @@ struct bCopyAlpha
 };
 
 struct bOverlay
-{
+{	
 	static __forceinline void OpC(BYTE &d, BYTE s, BYTE a, FCopyInfo *i) { d = (s*a + d*(255-a))/255; }
 	static __forceinline void OpA(BYTE &d, BYTE s, FCopyInfo *i) { d = MAX(s,d); }
 	static __forceinline bool ProcessAlpha0() { return false; }
diff --git a/src/textures/multipatchtexture.cpp b/src/textures/multipatchtexture.cpp
index b0db481a8..41ba5f0f2 100644
--- a/src/textures/multipatchtexture.cpp
+++ b/src/textures/multipatchtexture.cpp
@@ -628,8 +628,9 @@ int FMultiPatchTexture::CopyTrueColorPixels(FBitmap *bmp, int x, int y, int rota
 		{
 			ret = Parts[i].Texture->CopyTrueColorPixels(bmp, x+Parts[i].OriginX, y+Parts[i].OriginY, Parts[i].Rotate, &info);
 		}
-
-		if (ret > retv) retv = ret;
+		// treat -1 (i.e. unknown) as absolute. We have no idea if this may have overwritten previous info so a real check needs to be done.
+		if (ret == -1) retv = ret;
+		else if (retv != -1 && ret > retv) retv = ret;
 	}
 	// Restore previous clipping rectangle.
 	bmp->SetClipRect(saved_cr);