From af53b8e106ea41e19b84e075c8cf093a9d905310 Mon Sep 17 00:00:00 2001
From: zeromus <zeromus@users.sf.net>
Date: Mon, 22 Jun 2009 06:09:37 +0000
Subject: [PATCH] gpu: add experimental handling for a case of translucent bmp
 obj blending

---
 desmume/src/GPU.cpp | 27 +++++++++++++++++++++++++--
 desmume/src/GPU.h   |  2 +-
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/desmume/src/GPU.cpp b/desmume/src/GPU.cpp
index 42a0bcce8..be5f7a3be 100644
--- a/desmume/src/GPU.cpp
+++ b/desmume/src/GPU.cpp
@@ -713,7 +713,7 @@ static void GPU_resortBGs(GPU *gpu)
 #endif
 }
 
-FORCEINLINE u16 GPU::blend(u16 colA, u16 colB)
+static FORCEINLINE u16 _blend(u16 colA, u16 colB, GPU::TBlendTable* blendTable)
 {
 	u8 r = (*blendTable)[colA&0x1F][colB&0x1F];
 	u8 g = (*blendTable)[(colA>>5)&0x1F][(colB>>5)&0x1F];
@@ -722,6 +722,11 @@ FORCEINLINE u16 GPU::blend(u16 colA, u16 colB)
 	return r|(g<<5)|(b<<10);
 }
 
+FORCEINLINE u16 GPU::blend(u16 colA, u16 colB)
+{
+	return _blend(colA, colB, blendTable);
+}
+
 
 void GPU_setMasterBrightness (GPU *gpu, u16 val)
 {
@@ -1105,6 +1110,15 @@ static void setFinalOBJColorSpecialNone(GPU *gpu, u32 passing, u8 *dst, u16 colo
 	}
 }
 
+static FORCEINLINE u16 blendSprite(GPU* gpu, u8 alpha, u16 sprColor, u16 backColor, u8 type)
+{
+	if(type == 3) 
+		//handle translucent bitmap sprite
+		return _blend(sprColor,backColor,&gpuBlendTable555[alpha+1][15-alpha]);
+	else 
+		return gpu->blend(sprColor,backColor);
+}
+
 static void setFinalOBJColorSpecialBlend(GPU *gpu, u32 passing, u8 *dst, u16 color, u8 alpha, u8 type, u16 x)
 {
 	if((gpu->BLDCNT & 0x10) || (type == 1))
@@ -1114,7 +1128,10 @@ static void setFinalOBJColorSpecialBlend(GPU *gpu, u32 passing, u8 *dst, u16 col
 
 		//If the layer we are drawing on is selected as 2nd source, we can blend
 		if((bg_under != 4) && (gpu->BLDCNT & (0x100 << bg_under)))
-			final = gpu->blend(color,T2ReadWord(dst, passing));
+		{
+			//bmp translucent handling tested by disgaea clock hud
+			final = blendSprite(gpu, alpha, color, T2ReadWord(dst, passing), type);
+		}
 		
 		T2WriteWord(dst, passing, (final | 0x8000));
 		gpu->bgPixels[x] = 4;
@@ -1232,7 +1249,9 @@ static void setFinalOBJColorSpecialBlendWnd(GPU *gpu, u32 passing, u8 *dst, u16
 
 			// If the layer we are drawing on is selected as 2nd source, we can blend
 			if((bg_under != 4) && (gpu->BLDCNT & (0x100 << bg_under)))
+			{
 				final = gpu->blend(color,T2ReadWord(dst, passing));
+			}
 
 			T2WriteWord(dst, passing, (final | 0x8000));
 			gpu->bgPixels[x] = 4;
@@ -2343,6 +2362,10 @@ void GPU::_spriteRender(u8 * dst, u8 * dst_alpha, u8 * typeTab, u8 * prioTab)
 			if (spriteInfo->Mode == 3)              /* sprite is in BMP format */
 			{
 
+				//transparent (i think, dont bother to render?) if alpha is 0
+				if(spriteInfo->PaletteIndex == 0)
+					continue;
+
 				if (dispCnt->OBJ_BMP_mapping)
 				{
 					//tested by buffy sacrifice damage blood splatters in corner
diff --git a/desmume/src/GPU.h b/desmume/src/GPU.h
index d0f3c4ac4..0c4da93e8 100644
--- a/desmume/src/GPU.h
+++ b/desmume/src/GPU.h
@@ -807,7 +807,7 @@ struct GPU
 	void setBLDALPHA(u16 val)
 	{
 		BLDALPHA_EVA = (val&0x1f) > 16 ? 16 : (val&0x1f); 
-		BLDALPHA_EVB = (val>>8&0x1f) > 16 ? 16 : (val>>8&0x1f);
+		BLDALPHA_EVB = ((val>>8)&0x1f) > 16 ? 16 : ((val>>8)&0x1f);
 		updateBLDALPHA();
 	}