gsdx ogl: find a way to workaround the buggy amd driver to support dual blending

git-svn-id: http://pcsx2.googlecode.com/svn/trunk@5203 96395faa-99c1-11dd-bbfe-3dabce05a288

plugins/GSdx/GSDeviceOGL.cpp

@@ -29,9 +29,6 @@
 //#define PRINT_FRAME_NUMBER
 //#define ONLY_LINES
 
-// It seems dual blending does not work on AMD !!!
-//#define DISABLE_DUAL_BLEND
-
 static uint32 g_draw_count = 0;
 static uint32 g_frame_count = 1;		
 
@@ -1236,6 +1233,40 @@ void GSDeviceOGL::OMSetRenderTargets(GSTexture* rt, GSTexture* ds, const GSVecto
 	}
 }
 
+// AMD drivers fail to support correctly the setting of index in fragment shader (layout statement in glsl)...
+// So instead to use directly glCreateShaderProgramv, you need to emulate the function and manually set 
+// the index in the fragment shader.
+GLuint GSDeviceOGL::glCreateShaderProgramv_AMD_BUG_WORKAROUND(GLenum  type,  GLsizei  count,  const char ** strings)
+{
+	const GLuint shader = glCreateShader(type);
+	if (shader) {
+		glShaderSource(shader, count, strings, NULL);
+		glCompileShader(shader);
+		const GLuint program = glCreateProgram();
+		if (program) {
+			GLint compiled = GL_FALSE;
+			glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
+			glProgramParameteri(program, GL_PROGRAM_SEPARABLE, GL_TRUE);
+			if (compiled) {
+				glAttachShader(program, shader);
+				// HACK TO SET CORRECTLY THE INDEX
+				if (type == GL_FRAGMENT_SHADER) {
+					glBindFragDataLocationIndexed(program, 0, 0, "SV_Target0");
+					glBindFragDataLocationIndexed(program, 0, 1, "SV_Target1");
+				}
+				// END OF HACK
+				glLinkProgram(program);
+				glDetachShader(program, shader);
+			}
+			/* append-shader-info-log-to-program-info-log */
+		}
+		glDeleteShader(shader);
+		return program;
+	} else {
+		return 0;
+	}
+}
+
 void GSDeviceOGL::CompileShaderFromSource(const std::string& glsl_file, const std::string& entry, GLenum type, GLuint* program, const std::string& macro_sel)
 {
 	// *****************************************************
@@ -1264,9 +1295,6 @@ void GSDeviceOGL::CompileShaderFromSource(const std::string& glsl_file, const st
 	std::string entry_main = format("#define %s main\n", entry.c_str());
 
 	std::string header = version + shader_type + entry_main + macro_sel;
-#ifdef DISABLE_DUAL_BLEND
-	header += "#define DISABLE_DUAL_BLEND 1\n";
-#endif
 
 	// *****************************************************
 	// Read the source file
@@ -1309,7 +1337,22 @@ void GSDeviceOGL::CompileShaderFromSource(const std::string& glsl_file, const st
 	header.copy(header_str, header.size(), 0);
 	header_str[header.size()] = '\0';
 
-	*program = glCreateShaderProgramv(type, 2, sources_array);
+	// ... See below to test that index is correctly set by driver
+	//*program = glCreateShaderProgramv(type, 2, sources_array);
+	*program = glCreateShaderProgramv_AMD_BUG_WORKAROUND(type, 2, sources_array);
+
+	// DEBUG AMD failure...
+	// GLint index = -1;
+
+	// index    = glGetFragDataIndex(*program,  "SV_Target0");
+	// fprintf(stderr, "Frag0 index %d\n", index);
+	// assert(index == 0);
+
+	// index    = glGetFragDataIndex(*program,  "SV_Target1");
+	// fprintf(stderr, "Frag1 index %d\n", index);
+	// assert(index == 1);
+	// END DEBUG AMD
+
 	free(source_str);
 	free(header_str);
 	free(sources_array);
@@ -1430,13 +1473,8 @@ void GSDeviceOGL::DebugOutputToFile(unsigned int source, unsigned int type, unsi
 #define D3DBLEND_BLENDFACTOR	GL_CONSTANT_COLOR
 #define D3DBLEND_INVBLENDFACTOR GL_ONE_MINUS_CONSTANT_COLOR
 
-#ifdef DISABLE_DUAL_BLEND
+#define D3DBLEND_SRCALPHA		GL_SRC1_ALPHA
-	#define D3DBLEND_SRCALPHA		GL_SRC_ALPHA
+#define D3DBLEND_INVSRCALPHA	GL_ONE_MINUS_SRC1_ALPHA
-	#define D3DBLEND_INVSRCALPHA	GL_ONE_MINUS_SRC_ALPHA
-#else
-	#define D3DBLEND_SRCALPHA		GL_SRC1_ALPHA
-	#define D3DBLEND_INVSRCALPHA	GL_ONE_MINUS_SRC1_ALPHA
-#endif
                         
 const GSDeviceOGL::D3D9Blend GSDeviceOGL::m_blendMapD3D9[3*3*3*3] =
 {

plugins/GSdx/GSDeviceOGL.h

@@ -919,4 +919,6 @@ class GSDeviceOGL : public GSDevice
 	void SetupGS(GSSelector sel);
 	void SetupPS(PSSelector sel, const PSConstantBuffer* cb, PSSamplerSelector ssel);
 	void SetupOM(OMDepthStencilSelector dssel, OMBlendSelector bsel, uint8 afix);
+
+	GLuint glCreateShaderProgramv_AMD_BUG_WORKAROUND(GLenum  type,  GLsizei  count,  const char ** strings);
 };

plugins/GSdx/res/tfx.glsl

@@ -261,12 +261,8 @@ void gs_main()
 layout(location = 0) in vertex PSin;
 
 // Same buffer but 2 colors for dual source blending
-#ifndef DISABLE_DUAL_BLEND
+layout(location = 0, index = 0) out vec4 SV_Target0;
-layout(location = 0, index = 1) out vec4 SV_Target0;
+layout(location = 0, index = 1) out vec4 SV_Target1;
-layout(location = 0, index = 0) out vec4 SV_Target1;
-#else
-layout(location = 0) out vec4 SV_Target1;
-#endif
 
 layout(binding = 0) uniform sampler2D TextureSampler;
 layout(binding = 1) uniform sampler2D PaletteSampler;
@@ -650,9 +646,7 @@ void ps_main()
 		if(c.a < 0.5) c.a += 0.5;
 	}
 
-    SV_Target1 = c;
+    SV_Target0 = c;
-#ifndef DISABLE_DUAL_BLEND
+    SV_Target1 = vec4(alpha, alpha, alpha, alpha);
-    SV_Target0 = vec4(alpha, alpha, alpha, alpha);
-#endif
 }
 #endif