From 37001d3640be199948990b9633a531e617ec7452 Mon Sep 17 00:00:00 2001
From: Randy Heit <rheit@zdoom.fake>
Date: Fri, 11 May 2012 02:26:50 +0000
Subject: [PATCH] - Added new patch style "Overlay" for TEXTURES. This is the
 same as CopyAlpha, except it only   copies the patch's alpha channel where it
 has a higher alpha than what's underneath.

SVN r3638 (trunk)
---
 src/textures/bitmap.cpp            | 2 ++
 src/textures/bitmap.h              | 8 ++++++++
 src/textures/multipatchtexture.cpp | 2 +-
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/textures/bitmap.cpp b/src/textures/bitmap.cpp
index cf419d70d..94b8ce774 100644
--- a/src/textures/bitmap.cpp
+++ b/src/textures/bitmap.cpp
@@ -206,6 +206,7 @@ static const CopyFunc copyfuncs[][9]={
 	COPY_FUNCS(bModulate),
 	COPY_FUNCS(bCopyAlpha),
 	COPY_FUNCS(bCopyNewAlpha),
+	COPY_FUNCS(bOverlay),
 	COPY_FUNCS(bOverwrite)
 };
 #undef COPY_FUNCS
@@ -422,6 +423,7 @@ static const CopyPalettedFunc copypalettedfuncs[]=
 	iCopyPaletted<cBGRA, bModulate>,
 	iCopyPaletted<cBGRA, bCopyAlpha>,
 	iCopyPaletted<cBGRA, bCopyNewAlpha>,
+	iCopyPaletted<cBGRA, bOverlay>,
 	iCopyPaletted<cBGRA, bOverwrite>
 };
 
diff --git a/src/textures/bitmap.h b/src/textures/bitmap.h
index dc125bf87..ef57f562d 100644
--- a/src/textures/bitmap.h
+++ b/src/textures/bitmap.h
@@ -319,6 +319,7 @@ enum ECopyOp
 	OP_MODULATE,
 	OP_COPYALPHA,
 	OP_COPYNEWALPHA,
+	OP_OVERLAY,
 	OP_OVERWRITE
 };
 
@@ -359,6 +360,13 @@ struct bCopyAlpha
 	static __forceinline bool ProcessAlpha0() { return false; }
 };
 
+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; }
+};
+
 struct bBlend
 {
 	static __forceinline void OpC(BYTE &d, BYTE s, BYTE a, FCopyInfo *i) { d = (d*i->invalpha + s*i->alpha) >> FRACBITS; }
diff --git a/src/textures/multipatchtexture.cpp b/src/textures/multipatchtexture.cpp
index 5799ad04e..220a25a2f 100644
--- a/src/textures/multipatchtexture.cpp
+++ b/src/textures/multipatchtexture.cpp
@@ -1180,7 +1180,7 @@ void FMultiPatchTexture::ParsePatch(FScanner &sc, TexPart & part, bool silent, i
 			}
 			else if (sc.Compare("style"))
 			{
-				static const char *styles[] = {"copy", "translucent", "add", "subtract", "reversesubtract", "modulate", "copyalpha", "copynewalpha", NULL };
+				static const char *styles[] = {"copy", "translucent", "add", "subtract", "reversesubtract", "modulate", "copyalpha", "copynewalpha", "overlay", NULL };
 				sc.MustGetString();
 				part.op = sc.MustMatchString(styles);
 				bComplex |= (part.op != OP_COPY);