From 4daa21ecdfad9cd6a5b0f6807f9db90dfe10eb73 Mon Sep 17 00:00:00 2001
From: Joshua Granick <joshua@joshuagranick.com>
Date: Fri, 14 Mar 2014 03:18:51 -0700
Subject: [PATCH] Work on premultiplied alpha

---
 project/Build.xml                             | 2 ++
 project/include/renderer/common/Surface.h     | 4 ++++
 project/src/renderer/opengl/OpenGLContext.cpp | 4 ++++
 project/src/renderer/opengl/OpenGLProgram.cpp | 4 ++++
 4 files changed, 14 insertions(+)

diff --git a/project/Build.xml b/project/Build.xml
index 333415ecd..a5d5df1bc 100644
--- a/project/Build.xml
+++ b/project/Build.xml
@@ -281,6 +281,7 @@
 		<compilerflag value="-DGLFW_OGL" if="glfw"/>
 		<compilerflag value="-DLIME_CURL_SSL" if="ssl" unless="nocurl"/>
 		<compilerflag value="-DLIME_FORCE_GLES1" if="LIME_FORCE_GLES1"/>
+		<compilerflag value="-DLIME_PREMULTIPLIED_ALPHA" if="LIME_PREMULTIPLIED_ALPHA"/>
 		<compilerflag value="-Wno-conversion" if="linux"/>
 
 		<!-- <file name="src/common/Surface.cpp"/> -->
@@ -356,6 +357,7 @@
 		<compilerflag value="-DGLFW_OGL" if="glfw"/>
 		<compilerflag value="-DLIME_CURL_SSL" if="ssl" unless="nocurl"/>
 		<compilerflag value="-DLIME_FORCE_GLES1" if="LIME_FORCE_GLES1"/>
+		<compilerflag value="-DLIME_PREMULTIPLIED_ALPHA" if="LIME_PREMULTIPLIED_ALPHA"/>
 		<compilerflag value="-Wno-conversion" if="linux"/>
 		
 		<file name="src/renderer/opengl/OpenGLInit.cpp"/>
diff --git a/project/include/renderer/common/Surface.h b/project/include/renderer/common/Surface.h
index 00dd9e23b..9627ef213 100644
--- a/project/include/renderer/common/Surface.h
+++ b/project/include/renderer/common/Surface.h
@@ -28,7 +28,11 @@ namespace lime {
 		
 		public:
 			
+			#ifdef LIME_PREMULTIPLIED_ALPHA
+			Surface () : mTexture (0), mVersion (0), mFlags (SURF_FLAGS_NOT_REPEAT_IF_NON_PO2 | SURF_FLAGS_USE_PREMULTIPLIED_ALPHA), mAllowTrans (true) {}; // Non-PO2 will generate dodgy repeating anyhow...
+			#else
 			Surface () : mTexture (0), mVersion (0), mFlags (SURF_FLAGS_NOT_REPEAT_IF_NON_PO2), mAllowTrans (true) {}; // Non-PO2 will generate dodgy repeating anyhow...
+			#endif
 			
 			virtual RenderTarget BeginRender (const Rect &inRect, bool inForHitTest = false) = 0;
 			virtual void BlitChannel (const RenderTarget &outTarget, const Rect &inSrcRect, int inPosX, int inPosY, int inSrcChannel, int inDestChannel) const = 0;
diff --git a/project/src/renderer/opengl/OpenGLContext.cpp b/project/src/renderer/opengl/OpenGLContext.cpp
index 9e60e2012..908bab749 100644
--- a/project/src/renderer/opengl/OpenGLContext.cpp
+++ b/project/src/renderer/opengl/OpenGLContext.cpp
@@ -404,7 +404,11 @@ namespace lime {
 			}
 			
 			int progId = 0;
+			#ifdef LIME_PREMULTIPLIED_ALPHA
+			bool premAlpha = true;
+			#else
 			bool premAlpha = false;
+			#endif
 			
 			if ((element.mFlags & DRAW_HAS_TEX) && element.mSurface) {
 				
diff --git a/project/src/renderer/opengl/OpenGLProgram.cpp b/project/src/renderer/opengl/OpenGLProgram.cpp
index 137828482..35d6cdf98 100644
--- a/project/src/renderer/opengl/OpenGLProgram.cpp
+++ b/project/src/renderer/opengl/OpenGLProgram.cpp
@@ -231,7 +231,11 @@ namespace lime {
 			
 			if (mColourScaleSlot >= 0) {
 				
+				#ifdef LIME_PREMULTIPLIED_ALPHA
+				glUniform4f (mColourScaleSlot, inTransform->redMultiplier * inTransform->alphaMultiplier * rf, inTransform->greenMultiplier * inTransform->alphaMultiplier * gf, inTransform->blueMultiplier * inTransform->alphaMultiplier * bf, inTransform->alphaMultiplier * af);
+				#else
 				glUniform4f (mColourScaleSlot, inTransform->redMultiplier * rf, inTransform->greenMultiplier * gf, inTransform->blueMultiplier * bf, inTransform->alphaMultiplier * af);
+				#endif
 				
 			}