From 7ddbd4f886510f1a0064be32aed0ea24c38ce403 Mon Sep 17 00:00:00 2001
From: engineer_apple <engineer_apple@dfc29bdd-3216-0410-991c-e03cc46cb475>
Date: Wed, 11 Feb 2009 23:53:15 +0000
Subject: [PATCH] - destination alpha saving for CImage

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@2211 dfc29bdd-3216-0410-991c-e03cc46cb475
---
 examples/21.Quake3Explorer/main.cpp      |  1 +
 source/Irrlicht/CImage.cpp               | 18 +++++++++------
 source/Irrlicht/SoftwareDriver2_helper.h | 29 ++++++++++++++++--------
 3 files changed, 31 insertions(+), 17 deletions(-)

diff --git a/examples/21.Quake3Explorer/main.cpp b/examples/21.Quake3Explorer/main.cpp
index 0b0bceb6..f8cf762a 100644
--- a/examples/21.Quake3Explorer/main.cpp
+++ b/examples/21.Quake3Explorer/main.cpp
@@ -2052,6 +2052,7 @@ void runGame ( GameData *game )
 	#pragma comment(linker, "/subsystem:windows /ENTRY:mainCRTStartup")
 #endif
 
+
 /*!
 */
 int IRRCALLCONV main(int argc, char* argv[])
diff --git a/source/Irrlicht/CImage.cpp b/source/Irrlicht/CImage.cpp
index 9866863a..ad9a36ce 100644
--- a/source/Irrlicht/CImage.cpp
+++ b/source/Irrlicht/CImage.cpp
@@ -287,9 +287,10 @@ static void RenderLine32_Blend(video::IImage *t,
 	m = dy << 1;
 
 	run = dx;
+	const u32 packA = packAlpha ( alpha );
 	while ( run )
 	{
-		*dst = PixelBlend32( *dst, argb, alpha );
+		*dst = packA | PixelBlend32( *dst, argb, alpha );
 
 		dst = (u32*) ( (u8*) dst + xInc );	// x += xInc
 		d += m;
@@ -374,8 +375,8 @@ static void RenderLine16_Decal(video::IImage *t,
 static void RenderLine16_Blend(video::IImage *t,
 				const core::position2d<s32> &p0,
 				const core::position2d<s32> &p1,
-				u32 argb,
-				u32 alpha)
+				u16 argb,
+				u16 alpha)
 {
 	s32 dx = p1.X - p0.X;
 	s32 dy = p1.Y - p0.Y;
@@ -418,9 +419,10 @@ static void RenderLine16_Blend(video::IImage *t,
 	m = dy << 1;
 
 	run = dx;
+	const u16 packA = alpha ? 0x8000 : 0;
 	while ( run )
 	{
-		*dst = PixelBlend16( *dst, argb, alpha );
+		*dst = packA | PixelBlend16( *dst, argb, alpha );
 
 		dst = (u16*) ( (u8*) dst + xInc );	// x += xInc
 		d += m;
@@ -724,14 +726,16 @@ static void executeBlit_ColorAlpha_16_to_16( const SBlitJob * job )
 {
 	u16 *dst = (u16*) job->dst;
 
-	const u32 alpha = extractAlpha( job->argb ) >> 3;
+	const u16 alpha = extractAlpha( job->argb ) >> 3;
+	if ( 0 == alpha )
+		return;
 	const u32 src = video::A8R8G8B8toA1R5G5B5( job->argb );
 
 	for ( s32 dy = 0; dy != job->height; ++dy )
 	{
 		for ( s32 dx = 0; dx != job->width; ++dx )
 		{
-			dst[dx] = PixelBlend16( dst[dx], src, alpha );
+			dst[dx] = 0x8000 | PixelBlend16( dst[dx], src, alpha );
 		}
 		dst = (u16*) ( (u8*) (dst) + job->dstPitch );
 	}
@@ -750,7 +754,7 @@ static void executeBlit_ColorAlpha_32_to_32( const SBlitJob * job )
 	{
 		for ( s32 dx = 0; dx != job->width; ++dx )
 		{
-			dst[dx] = PixelBlend32( dst[dx], src, alpha );
+			dst[dx] = (job->argb & 0xFF000000 ) | PixelBlend32( dst[dx], src, alpha );
 		}
 		dst = (u32*) ( (u8*) (dst) + job->dstPitch );
 	}
diff --git a/source/Irrlicht/SoftwareDriver2_helper.h b/source/Irrlicht/SoftwareDriver2_helper.h
index b8da7541..41d9e977 100644
--- a/source/Irrlicht/SoftwareDriver2_helper.h
+++ b/source/Irrlicht/SoftwareDriver2_helper.h
@@ -182,17 +182,17 @@ REALINLINE u32 PixelBlend32 ( const u32 c2, const u32 c1, u32 alpha )
 	Pixel = dest * ( 1 - alpha ) + source * alpha
 	alpha [0;32]
 */
-inline u16 PixelBlend16 ( const u16 c2, const u32 c1, const u32 alpha )
+inline u16 PixelBlend16 ( const u16 c2, const u32 c1, const u16 alpha )
 {
-	u32 srcRB = c1 & 0x7C1F;
-	u32 srcXG = c1 & 0x03E0;
+	u16 srcRB = c1 & 0x7C1F;
+	u16 srcXG = c1 & 0x03E0;
 
-	u32 dstRB = c2 & 0x7C1F;
-	u32 dstXG = c2 & 0x03E0;
+	u16 dstRB = c2 & 0x7C1F;
+	u16 dstXG = c2 & 0x03E0;
 
 
-	u32 rb = srcRB - dstRB;
-	u32 xg = srcXG - dstXG;
+	u16 rb = srcRB - dstRB;
+	u16 xg = srcXG - dstXG;
 
 	rb *= alpha;
 	xg *= alpha;
@@ -230,14 +230,23 @@ inline u32 PixelLerp32 ( const u32 source, const u32 value )
 }
 
 /*
-	return alpha in [0;256] Granularity
-	 add highbit alpha ( alpha > 127 ? + 1 )
+	return alpha in [0;256] Granularity rom 32-Bit ARGB
+	add highbit alpha ( alpha > 127 ? + 1 )
 */
 inline u32 extractAlpha ( const u32 c )
 {
 	return ( c >> 24 ) + ( c >> 31 );
 }
 
+/*
+	return alpha in [0;255] Granularity and 32-Bit ARGB
+	add highbit alpha ( alpha > 127 ? + 1 )
+*/
+inline u32 packAlpha ( const u32 c )
+{
+	return (c > 127 ? c - 1 : c) << 24;
+}
+
 /*
 	Pixel = c0 * (c1/31). c0 Alpha retain
 */
@@ -384,7 +393,7 @@ inline u32 PixelBlend32 ( const u32 c2, const u32 c1 )
 	rb &= 0x00FF00FF;
 	xg &= 0x0000FF00;
 
-	return rb | xg;
+	return (c1 & 0xFF000000) | rb | xg;
 }