gsdx ogl: Extend uniform buffer with channel parameter

Instead to use the standard ps ubo which is used every draw call.
I reused a barely used buffer to reduce the extra cost of the upload

plugins/GSdx/GSDevice.h

@@ -49,14 +49,6 @@ enum ShaderConvert {
 
 #pragma pack(push, 1)
 
-class ConvertConstantBuffer
-{
-public:
-	GSVector4i ScalingFactor;
-
-	ConvertConstantBuffer() {memset(this, 0, sizeof(*this));}
-};
-
 class MergeConstantBuffer
 {
 public:

plugins/GSdx/GSDeviceOGL.cpp

@@ -256,11 +256,10 @@ bool GSDeviceOGL::Create(GSWnd* wnd)
 	{
 		GL_PUSH("GSDeviceOGL::Convert");
 
-		m_convert.cb = new GSUniformBufferOGL(g_convert_index, sizeof(ConvertConstantBuffer));
+		m_convert.cb = new GSUniformBufferOGL(g_convert_index, sizeof(MiscConstantBuffer));
 		// Upload once and forget about it
-		ConvertConstantBuffer cb;
-		cb.ScalingFactor = GSVector4i(theApp.GetConfigI("upscale_multiplier"));
-		m_convert.cb->cache_upload(&cb);
+		m_misc_cb_cache.ScalingFactor = GSVector4i(theApp.GetConfigI("upscale_multiplier"));
+		m_convert.cb->cache_upload(&m_misc_cb_cache);
 
 		vs = m_shader->Compile("convert.glsl", "vs_main", GL_VERTEX_SHADER, convert_glsl);
 
@@ -1567,6 +1566,12 @@ void GSDeviceOGL::SetupCB(const VSConstantBuffer* vs_cb, const PSConstantBuffer*
 	}
 }
 
+void GSDeviceOGL::SetupCBMisc(const GSVector4i& channel)
+{
+	m_misc_cb_cache.ChannelShuffle = channel;
+	m_convert.cb->cache_upload(&m_misc_cb_cache);
+}
+
 void GSDeviceOGL::SetupPipeline(const VSSelector& vsel, const GSSelector& gsel, const PSSelector& psel)
 {
 	// *************************************************************

plugins/GSdx/GSDeviceOGL.h

@@ -380,6 +380,14 @@ public:
 		OMColorMaskSelector(uint32 c) { wrgba = c; }
 	};
 
+	struct alignas(32) MiscConstantBuffer
+	{
+		GSVector4i ScalingFactor;
+		GSVector4i ChannelShuffle;
+
+		MiscConstantBuffer() {memset(this, 0, sizeof(*this));}
+	};
+
 	struct OGLBlend {uint16 bogus, op, src, dst;};
 	static const OGLBlend m_blendMapOGL[3*3*3*3 + 1];
 	static const int m_NO_BLEND;
@@ -453,6 +461,7 @@ public:
 
 	VSConstantBuffer m_vs_cb_cache;
 	PSConstantBuffer m_ps_cb_cache;
+	MiscConstantBuffer m_misc_cb_cache;
 
 	GSTexture* CreateSurface(int type, int w, int h, bool msaa, int format);
 	GSTexture* FetchSurface(int type, int w, int h, bool msaa, int format);
@@ -546,6 +555,7 @@ public:
 	void SetupIA(const void* vertex, int vertex_count, const uint32* index, int index_count, int prim);
 	void SetupPipeline(const VSSelector& vsel, const GSSelector& gsel, const PSSelector& psel);
 	void SetupCB(const VSConstantBuffer* vs_cb, const PSConstantBuffer* ps_cb);
+	void SetupCBMisc(const GSVector4i& channel);
 	void SetupSampler(PSSamplerSelector ssel);
 	void SetupOM(OMDepthStencilSelector dssel);
 	GLuint GetSamplerID(PSSamplerSelector ssel);

plugins/GSdx/res/glsl/common_header.glsl

@@ -61,6 +61,7 @@ layout(std140, binding = 14) uniform cb14
 layout(std140, binding = 15) uniform cb15
 {
     ivec4 ScalingFactor;
+    ivec4 ChannelShuffle;
 };
 
 layout(std140, binding = 20) uniform cb20

plugins/GSdx/res/glsl_source.h

@@ -86,6 +86,7 @@ static const char* const common_header_glsl =
 	"layout(std140, binding = 15) uniform cb15\n"
 	"{\n"
 	"    ivec4 ScalingFactor;\n"
+	"    ivec4 ChannelShuffle;\n"
 	"};\n"
 	"\n"
 	"layout(std140, binding = 20) uniform cb20\n"