fixes for my last commit

Source/Core/VideoCommon/Src/PixelShaderGen.cpp

@@ -844,14 +844,14 @@ const char *GeneratePixelShaderCode(DSTALPHA_MODE dstAlphaMode, API_TYPE ApiType
 		WRITE(p, "\tocol0 = prev;\n");
 	}
 
-	// On D3D11, use dual-source color blending to perform dst alpha in a
+	// Use dual-source color blending to perform dst alpha in a
 	// single pass
 	if (dstAlphaMode == DSTALPHA_DUAL_SOURCE_BLEND)
 	{
 		if(ApiType & API_D3D9)
 		{
-			//Colors will be blended against the color from ocol1 in D3D 9...
-			//ALPHA must be 0 or the shader will not compile( direct3d9 ex resriction)
+			// alpha component must be 0 or the shader will not compile (Direct3D 9Ex restriction)
+			// Colors will be blended against the color from ocol1 in D3D 9...			
 			WRITE(p, "\tocol1 = float4(prev.a, prev.a, prev.a, 0.0f);\n");			
 		}
 		else

Source/Plugins/Plugin_VideoDX9/Src/Render.cpp

@@ -661,6 +661,8 @@ void Renderer::SetBlendMode(bool forceUpdate)
 	// Our render target always uses an alpha channel, so we need to override the blend functions to assume a destination alpha of 1 if the render target isn't supposed to have an alpha channel
 	// Example: D3DBLEND_DESTALPHA needs to be D3DBLEND_ONE since the result without an alpha channel is assumed to always be 1.
 	bool target_has_alpha = bpmem.zcontrol.pixel_format == PIXELFMT_RGBA6_Z24;
+	//bDstAlphaPass is taked in account because the ability of disabling alpha composition is
+	//really usefull for debuging shader and blending errors
 	bool useDstAlpha = !g_ActiveConfig.bDstAlphaPass && bpmem.dstalpha.enable && bpmem.blendmode.alphaupdate && target_has_alpha;
 	bool useDualSource = useDstAlpha && g_ActiveConfig.backend_info.bSupportsDualSourceBlend;
 	const D3DBLEND d3dSrcFactors[8] =
@@ -692,10 +694,10 @@ void Renderer::SetBlendMode(bool forceUpdate)
 		return;
 	}
 
-	bool BlendEnable = bpmem.blendmode.subtract || bpmem.blendmode.blendenable;
-	D3D::SetRenderState(D3DRS_ALPHABLENDENABLE, BlendEnable);
-	D3D::SetRenderState(D3DRS_SEPARATEALPHABLENDENABLE , BlendEnable);
-	if (BlendEnable)
+	bool blend_enable = bpmem.blendmode.subtract || bpmem.blendmode.blendenable;
+	D3D::SetRenderState(D3DRS_ALPHABLENDENABLE, blend_enable);
+	D3D::SetRenderState(D3DRS_SEPARATEALPHABLENDENABLE, blend_enable);
+	if (blend_enable)
  	{
 		D3DBLENDOP op = D3DBLENDOP_ADD;
 		u32 srcidx = bpmem.blendmode.srcfactor;

Source/Plugins/Plugin_VideoDX9/Src/main.cpp

@@ -102,19 +102,19 @@ void InitBackendInfo()
 	g_Config.backend_info.bUseMinimalMipCount = true;
 	g_Config.backend_info.bSupports3DVision = true;
 	OSVERSIONINFO info;
-    ZeroMemory(&info, sizeof(OSVERSIONINFO));
-    info.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
-    if (GetVersionEx(&info))
-    {
+	ZeroMemory(&info, sizeof(OSVERSIONINFO));
+	info.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
+	if (GetVersionEx(&info))
+	{
 		// dual source blending is only supported in windows 7 o newer. sorry xp users
+		// we cannot test for device caps because most drivers just declare the minimun caps
+		// and don't expose their support for some functionalities		
 		g_Config.backend_info.bSupportsDualSourceBlend = info.dwPlatformId == VER_PLATFORM_WIN32_NT && info.dwMajorVersion > 5;
 	}
 	else
 	{
 		g_Config.backend_info.bSupportsDualSourceBlend = false;
 	}
-
-
 	g_Config.backend_info.bSupportsFormatReinterpretation = true;
 	g_Config.backend_info.bSupportsPixelLighting = C_PLIGHTS + 40 <= maxConstants && C_PMATERIALS + 4 <= maxConstants;