engine: ref_api: comment unused opengl attributes

engine/ref_api.h

@@ -176,20 +176,20 @@ enum // OpenGL configuration attributes
 	REF_GL_GREEN_SIZE,
 	REF_GL_BLUE_SIZE,
 	REF_GL_ALPHA_SIZE,
-	REF_GL_BUFFER_SIZE,
+	// UNUSED_REF_GL_BUFFER_SIZE,
-	REF_GL_DOUBLEBUFFER,
+	REF_GL_DOUBLEBUFFER = REF_GL_ALPHA_SIZE + 1,
 	REF_GL_DEPTH_SIZE,
 	REF_GL_STENCIL_SIZE,
-	REF_GL_ACCUM_RED_SIZE,
+	// UNUSED_REF_GL_ACCUM_RED_SIZE,
-	REF_GL_ACCUM_GREEN_SIZE,
+	// UNUSED_REF_GL_ACCUM_GREEN_SIZE,
-	REF_GL_ACCUM_BLUE_SIZE,
+	// UNUSED_REF_GL_ACCUM_BLUE_SIZE,
-	REF_GL_ACCUM_ALPHA_SIZE,
+	// UNUSED_REF_GL_ACCUM_ALPHA_SIZE,
-	REF_GL_STEREO,
+	// UNUSED_REF_GL_STEREO,
-	REF_GL_MULTISAMPLEBUFFERS,
+	REF_GL_MULTISAMPLEBUFFERS = REF_GL_STENCIL_SIZE + 5,
 	REF_GL_MULTISAMPLESAMPLES,
 	REF_GL_ACCELERATED_VISUAL,
-	REF_GL_RETAINED_BACKING,
+	// UNUSED_REF_GL_RETAINED_BACKING,
-	REF_GL_CONTEXT_MAJOR_VERSION,
+	REF_GL_CONTEXT_MAJOR_VERSION = REF_GL_ACCELERATED_VISUAL + 1,
 	REF_GL_CONTEXT_MINOR_VERSION,
 	REF_GL_CONTEXT_EGL,
 	REF_GL_CONTEXT_FLAGS,
@@ -198,7 +198,8 @@ enum // OpenGL configuration attributes
 	REF_GL_FRAMEBUFFER_SRGB_CAPABLE,
 	REF_GL_CONTEXT_RELEASE_BEHAVIOR,
 	REF_GL_CONTEXT_RESET_NOTIFICATION,
-	REF_GL_CONTEXT_NO_ERROR
+	REF_GL_CONTEXT_NO_ERROR,
+	REF_GL_ATTRIBUTES_COUNT,
 };
 
 enum
@@ -208,6 +209,7 @@ enum
 	REF_GL_CONTEXT_PROFILE_ES             = 0x0004 /**< GLX_CONTEXT_ES2_PROFILE_BIT_EXT */
 };
 
+// binary compatible with SDL and EGL_KHR_create_context(0x0007 mask)
 enum
 {
 	REF_GL_CONTEXT_DEBUG_FLAG              = 0x0001,