gsdx-ogl: Make GL_ARB_draw_buffers_blend optinal for limited DX10 drivers

plugins/GSdx/GLLoader.cpp

@@ -84,6 +84,8 @@ PFNGLFENCESYNCPROC                     gl_FenceSync                         = NU
 PFNGLDELETESYNCPROC                    gl_DeleteSync                        = NULL;
 PFNGLCLIENTWAITSYNCPROC                gl_ClientWaitSync                    = NULL;
 PFNGLFLUSHMAPPEDBUFFERRANGEPROC        gl_FlushMappedBufferRange            = NULL;
+PFNGLBLENDEQUATIONSEPARATEPROC         gl_BlendEquationSeparate             = NULL;
+PFNGLBLENDFUNCSEPARATEPROC             gl_BlendFuncSeparate                 = NULL;
 // GL4.0
 PFNGLUNIFORMSUBROUTINESUIVPROC         gl_UniformSubroutinesuiv             = NULL;
 // GL4.1
@@ -326,6 +328,7 @@ namespace GLLoader {
 	bool found_geometry_shader = true; // we require GL3.3 so geometry must be supported by default
 	bool found_GL_EXT_texture_filter_anisotropic = false;
 	bool found_GL_ARB_clear_texture = false; // Don't know if GL3 GPU can support it
+	bool found_GL_ARB_draw_buffers_blend = false; // DX10 GPU limited driver on windows!
 
 	// Note: except Apple, all drivers support explicit uniform location
 	bool found_GL_ARB_explicit_uniform_location = false; // need by subroutine and bindless texture
@@ -345,7 +348,6 @@ namespace GLLoader {
 	// Mandatory
 	bool found_GL_ARB_texture_storage = false;
 	bool found_GL_ARB_shading_language_420pack = false;
-	bool found_GL_ARB_draw_buffers_blend = false; // could be easily be optional, but I'm lazy
 
 	static bool status_and_override(bool& found, const std::string& name, bool mandatory = false)
 	{
@@ -475,7 +477,7 @@ namespace GLLoader {
 		status &= status_and_override(found_GL_EXT_texture_filter_anisotropic, "GL_EXT_texture_filter_anisotropic");
 		// GL4.0
 		status &= status_and_override(found_GL_ARB_gpu_shader5, "GL_ARB_gpu_shader5");
-		status &= status_and_override(found_GL_ARB_draw_buffers_blend, "GL_ARB_draw_buffers_blend", true);
+		status &= status_and_override(found_GL_ARB_draw_buffers_blend, "GL_ARB_draw_buffers_blend");
 		// GL4.1
 		status &= status_and_override(found_GL_ARB_separate_shader_objects, "GL_ARB_separate_shader_objects");
 		status &= status_and_override(found_GL_ARB_shader_subroutine, "GL_ARB_shader_subroutine");

plugins/GSdx/GLLoader.h

@@ -268,6 +268,8 @@ extern   PFNGLFENCESYNCPROC                     gl_FenceSync;
 extern   PFNGLDELETESYNCPROC                    gl_DeleteSync;
 extern   PFNGLCLIENTWAITSYNCPROC                gl_ClientWaitSync;
 extern   PFNGLFLUSHMAPPEDBUFFERRANGEPROC        gl_FlushMappedBufferRange;
+extern   PFNGLBLENDEQUATIONSEPARATEPROC         gl_BlendEquationSeparate;
+extern   PFNGLBLENDFUNCSEPARATEPROC             gl_BlendFuncSeparate;
 // GL4.0
 extern   PFNGLUNIFORMSUBROUTINESUIVPROC         gl_UniformSubroutinesuiv;
 // GL4.1

plugins/GSdx/GSDeviceOGL.h

@@ -99,12 +99,18 @@ public:
 
 			if (GLState::eq_RGB != m_equation_RGB) {
 				GLState::eq_RGB = m_equation_RGB;
-				gl_BlendEquationSeparateiARB(0, m_equation_RGB, GL_FUNC_ADD);
+				if (gl_BlendEquationSeparateiARB)
+					gl_BlendEquationSeparateiARB(0, m_equation_RGB, GL_FUNC_ADD);
+				else
+					gl_BlendEquationSeparate(m_equation_RGB, GL_FUNC_ADD);
 			}
 			if (GLState::f_sRGB != m_func_sRGB || GLState::f_dRGB != m_func_dRGB) {
 				GLState::f_sRGB = m_func_sRGB;
 				GLState::f_dRGB = m_func_dRGB;
-				gl_BlendFuncSeparateiARB(0, m_func_sRGB, m_func_dRGB, GL_ONE, GL_ZERO);
+				if (gl_BlendFuncSeparateiARB)
+					gl_BlendFuncSeparateiARB(0, m_func_sRGB, m_func_dRGB, GL_ONE, GL_ZERO);
+				else
+					gl_BlendFuncSeparate(m_func_sRGB, m_func_dRGB, GL_ONE, GL_ZERO);
 			}
 		}
 	}

plugins/GSdx/GSWnd.cpp

@@ -27,14 +27,14 @@ void GSWndGL::PopulateGlFunction()
 {
 	*(void**)&(gl_ActiveTexture) = GetProcAddress("glActiveTexture");
 	*(void**)&(gl_BlendColor) = GetProcAddress("glBlendColor");
+	*(void**)&(gl_BlendEquationSeparate) = GetProcAddress("glBlendEquationSeparate");
+	*(void**)&(gl_BlendFuncSeparate) = GetProcAddress("glBlendFuncSeparate");
 	*(void**)&(gl_AttachShader) = GetProcAddress("glAttachShader");
 	*(void**)&(gl_BindBuffer) = GetProcAddress("glBindBuffer");
 	*(void**)&(gl_BindBufferBase) = GetProcAddress("glBindBufferBase");
 	*(void**)&(gl_BindFramebuffer) = GetProcAddress("glBindFramebuffer");
 	*(void**)&(gl_BindSampler) = GetProcAddress("glBindSampler");
 	*(void**)&(gl_BindVertexArray) = GetProcAddress("glBindVertexArray");
-	*(void**)&(gl_BlendEquationSeparateiARB) = GetProcAddress("glBlendEquationSeparateiARB");
-	*(void**)&(gl_BlendFuncSeparateiARB) = GetProcAddress("glBlendFuncSeparateiARB");
 	*(void**)&(gl_BlitFramebuffer) = GetProcAddress("glBlitFramebuffer");
 	*(void**)&(gl_BufferData) = GetProcAddress("glBufferData");
 	*(void**)&(gl_CheckFramebufferStatus) = GetProcAddress("glCheckFramebufferStatus");
@@ -81,6 +81,8 @@ void GSWndGL::PopulateGlFunction()
 	*(void**)&(gl_FlushMappedBufferRange) = GetProcAddress("glFlushMappedBufferRange");
 	// GL4.0
 	*(void**)&(gl_UniformSubroutinesuiv) = GetProcAddress("glUniformSubroutinesuiv", true);
+	*(void**)&(gl_BlendEquationSeparateiARB) = GetProcAddress("glBlendEquationSeparateiARB", true);
+	*(void**)&(gl_BlendFuncSeparateiARB) = GetProcAddress("glBlendFuncSeparateiARB", true);
 	// GL4.1
 	*(void**)&(gl_CreateShaderProgramv) = GetProcAddress("glCreateShaderProgramv", true);
 	*(void**)&(gl_BindProgramPipeline) = GetProcAddress("glBindProgramPipeline", true);