Fall back to GLES2 if GLES3 is not working

This adds a static is_viable() method to all rasterizers which has to be
called before initializing the rasterizer. This allows us to check what
rasterizer to use in OS::initialize together with the GL context
initialization.

This commit also adds a new project setting
"rendering/quality/driver/driver_fallback" which allows the creator of a
project to specify whether or not fallback to GLES2 is allowed. This
setting is ignored for the editor so the editor will always open even if
the project itself cannot run. This will hopefully reduce confusion for
users downloading projects from the internet.

We also no longer crash when GLES3 is not functioning on a platform.

This fixes #15324

16 files changed, 405 insertions, 159 deletions

diff --git a/doc/classes/ProjectSettings.xml b/doc/classes/ProjectSettings.xml
index 358b7292a5..5f828550b9 100644
--- a/doc/classes/ProjectSettings.xml
+++ b/doc/classes/ProjectSettings.xml
@@ -658,6 +658,9 @@
 		</member>
 		<member name="rendering/quality/driver/driver_name" type="String" setter="" getter="">
 		</member>
+		<member name="rendering/quality/driver/driver_fallback" type="String" setter="" getter="">
+			Whether to allow falling back to other graphics drivers if the preferred driver is not available. Best means use the best working driver (this is the default). Never means never fall back to another driver even if it does not work. This means the project will not run if the preferred driver does not function.
+		</member>
 		<member name="rendering/quality/filters/anisotropic_filter_level" type="int" setter="" getter="">
 			Maximum Anisotropic filter level used for textures when anisotropy enabled.
 		</member>
diff --git a/drivers/dummy/rasterizer_dummy.h b/drivers/dummy/rasterizer_dummy.h
index e39ec915fc..0381d3f0c1 100644
--- a/drivers/dummy/rasterizer_dummy.h
+++ b/drivers/dummy/rasterizer_dummy.h
@@ -789,6 +789,10 @@ public:
 	void end_frame(bool p_swap_buffers) {}
 	void finalize() {}
 
+	static Error is_viable() {
+		return OK;
+	}
+
 	static Rasterizer *_create_current() {
 		return memnew(RasterizerDummy);
 	}
diff --git a/drivers/gles2/rasterizer_gles2.cpp b/drivers/gles2/rasterizer_gles2.cpp
index c926f2bcc4..76ee80aa07 100644
--- a/drivers/gles2/rasterizer_gles2.cpp
+++ b/drivers/gles2/rasterizer_gles2.cpp
@@ -136,26 +136,21 @@ RasterizerScene *RasterizerGLES2::get_scene() {
 	return scene;
 }
 
-void RasterizerGLES2::initialize() {
-
-	print_verbose("Using GLES2 video driver");
+Error RasterizerGLES2::is_viable() {
 
 #ifdef GLAD_ENABLED
 	if (!gladLoadGL()) {
 		ERR_PRINT("Error initializing GLAD");
+		return ERR_UNAVAILABLE;
 	}
 
 // GLVersion seems to be used for both GL and GL ES, so we need different version checks for them
 #ifdef OPENGL_ENABLED // OpenGL 2.1 Profile required
-	if (GLVersion.major < 2) {
-#else // OpenGL ES 3.0
+	if (GLVersion.major < 2 || (GLVersion.major == 2 && GLVersion.minor < 1)) {
+#else // OpenGL ES 2.0
 	if (GLVersion.major < 2) {
 #endif
-		ERR_PRINT("Your system's graphic drivers seem not to support OpenGL 2.1 / OpenGL ES 2.0, sorry :(\n"
-				  "Try a drivers update, buy a new GPU or try software rendering on Linux; Godot will now crash with a segmentation fault.");
-		OS::get_singleton()->alert("Your system's graphic drivers seem not to support OpenGL 2.1 / OpenGL ES 2.0, sorry :(\n"
-								   "Godot Engine will self-destruct as soon as you acknowledge this error message.",
-				"Fatal error: Insufficient OpenGL / GLES driver support");
+		return ERR_UNAVAILABLE;
 	}
 
 #ifdef GLES_OVER_GL
@@ -181,14 +176,21 @@ void RasterizerGLES2::initialize() {
 			glGetFramebufferAttachmentParameteriv = glGetFramebufferAttachmentParameterivEXT;
 			glGenerateMipmap = glGenerateMipmapEXT;
 		} else {
-			ERR_PRINT("Your system's graphic drivers seem not to support GL_ARB(EXT)_framebuffer_object OpenGL extension, sorry :(\n"
-					  "Try a drivers update, buy a new GPU or try software rendering on Linux; Godot will now crash with a segmentation fault.");
-			OS::get_singleton()->alert("Your system's graphic drivers seem not to support GL_ARB(EXT)_framebuffer_object OpenGL extension, sorry :(\n"
-									   "Godot Engine will self-destruct as soon as you acknowledge this error message.",
-					"Fatal error: Insufficient OpenGL / GLES driver support");
+			return ERR_UNAVAILABLE;
 		}
 	}
 #endif
+
+#endif // GLAD_ENABLED
+
+	return OK;
+}
+
+void RasterizerGLES2::initialize() {
+
+	print_verbose("Using GLES2 video driver");
+
+#ifdef GLAD_ENABLED
 	if (true || OS::get_singleton()->is_stdout_verbose()) {
 		if (GLAD_GL_ARB_debug_output) {
 			glEnable(_EXT_DEBUG_OUTPUT_SYNCHRONOUS_ARB);
@@ -198,7 +200,6 @@ void RasterizerGLES2::initialize() {
 			print_line("OpenGL debugging not supported!");
 		}
 	}
-
 #endif // GLAD_ENABLED
 
 	// For debugging
diff --git a/drivers/gles2/rasterizer_gles2.h b/drivers/gles2/rasterizer_gles2.h
index f727af39dd..98c73b776b 100644
--- a/drivers/gles2/rasterizer_gles2.h
+++ b/drivers/gles2/rasterizer_gles2.h
@@ -61,9 +61,10 @@ public:
 	virtual void end_frame(bool p_swap_buffers);
 	virtual void finalize();
 
+	static Error is_viable();
 	static void make_current();
-
 	static void register_config();
+
 	RasterizerGLES2();
 	~RasterizerGLES2();
 };
diff --git a/drivers/gles3/rasterizer_gles3.cpp b/drivers/gles3/rasterizer_gles3.cpp
index 0d42635194..e4824695d5 100644
--- a/drivers/gles3/rasterizer_gles3.cpp
+++ b/drivers/gles3/rasterizer_gles3.cpp
@@ -136,28 +136,32 @@ typedef void (*DEBUGPROCARB)(GLenum source,
 
 typedef void (*DebugMessageCallbackARB)(DEBUGPROCARB callback, const void *userParam);
 
-void RasterizerGLES3::initialize() {
-
-	print_verbose("Using GLES3 video driver");
+Error RasterizerGLES3::is_viable() {
 
 #ifdef GLAD_ENABLED
 	if (!gladLoadGL()) {
 		ERR_PRINT("Error initializing GLAD");
+		return ERR_UNAVAILABLE;
 	}
 
 // GLVersion seems to be used for both GL and GL ES, so we need different version checks for them
 #ifdef OPENGL_ENABLED // OpenGL 3.3 Core Profile required
-	if (GLVersion.major < 3 && GLVersion.minor < 3) {
+	if (GLVersion.major < 3 || (GLVersion.major == 3 && GLVersion.minor < 3)) {
 #else // OpenGL ES 3.0
 	if (GLVersion.major < 3) {
 #endif
-		ERR_PRINT("Your system's graphic drivers seem not to support OpenGL 3.3 / OpenGL ES 3.0, sorry :(\n"
-				  "Try a drivers update, buy a new GPU or try software rendering on Linux; Godot will now crash with a segmentation fault.");
-		OS::get_singleton()->alert("Your system's graphic drivers seem not to support OpenGL 3.3 / OpenGL ES 3.0, sorry :(\n"
-								   "Godot Engine will self-destruct as soon as you acknowledge this error message.",
-				"Fatal error: Insufficient OpenGL / GLES driver support");
+		return ERR_UNAVAILABLE;
 	}
 
+#endif // GLAD_ENABLED
+	return OK;
+}
+
+void RasterizerGLES3::initialize() {
+
+	print_verbose("Using GLES3 video driver");
+
+#ifdef GLAD_ENABLED
 	if (OS::get_singleton()->is_stdout_verbose()) {
 		if (GLAD_GL_ARB_debug_output) {
 			glEnable(_EXT_DEBUG_OUTPUT_SYNCHRONOUS_ARB);
@@ -167,7 +171,6 @@ void RasterizerGLES3::initialize() {
 			print_line("OpenGL debugging not supported!");
 		}
 	}
-
 #endif // GLAD_ENABLED
 
 	/* // For debugging
diff --git a/drivers/gles3/rasterizer_gles3.h b/drivers/gles3/rasterizer_gles3.h
index f4449ac0f9..0a264caf8f 100644
--- a/drivers/gles3/rasterizer_gles3.h
+++ b/drivers/gles3/rasterizer_gles3.h
@@ -62,9 +62,10 @@ public:
 	virtual void end_frame(bool p_swap_buffers);
 	virtual void finalize();
 
+	static Error is_viable();
 	static void make_current();
-
 	static void register_config();
+
 	RasterizerGLES3();
 	~RasterizerGLES3();
 };
diff --git a/main/main.cpp b/main/main.cpp
index 21851337b7..a336496d39 100644
--- a/main/main.cpp
+++ b/main/main.cpp
@@ -830,6 +830,9 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 		video_driver = GLOBAL_GET("rendering/quality/driver/driver_name");
 	}
 
+	GLOBAL_DEF("rendering/quality/driver/driver_fallback", "Best");
+	ProjectSettings::get_singleton()->set_custom_property_info("rendering/quality/driver/driver_fallback", PropertyInfo(Variant::STRING, "rendering/quality/driver/driver_fallback", PROPERTY_HINT_ENUM, "Best,Never"));
+
 	GLOBAL_DEF("display/window/size/width", 1024);
 	GLOBAL_DEF("display/window/size/height", 600);
 	GLOBAL_DEF("display/window/size/resizable", true);
@@ -1040,6 +1043,7 @@ Error Main::setup2(Thread::ID p_main_tid_override) {
 	if (err != OK) {
 		return err;
 	}
+
 	if (init_use_custom_pos) {
 		OS::get_singleton()->set_window_position(init_custom_pos);
 	}
diff --git a/platform/android/os_android.cpp b/platform/android/os_android.cpp
index c8bdf98923..74c40bde72 100644
--- a/platform/android/os_android.cpp
+++ b/platform/android/os_android.cpp
@@ -62,12 +62,19 @@ public:
 
 int OS_Android::get_video_driver_count() const {
 
-	return 1;
+	return 2;
 }
 
 const char *OS_Android::get_video_driver_name(int p_driver) const {
 
-	return "GLES2";
+	switch (p_driver) {
+		case VIDEO_DRIVER_GLES3:
+			return "GLES3";
+		case VIDEO_DRIVER_GLES2:
+			return "GLES2";
+	}
+	ERR_EXPLAIN("Invalid video driver index " + itos(p_driver));
+	ERR_FAIL_V(NULL);
 }
 int OS_Android::get_audio_driver_count() const {
 
@@ -132,26 +139,55 @@ Error OS_Android::initialize(const VideoMode &p_desired, int p_video_driver, int
 
 	bool use_gl3 = get_gl_version_code_func() >= 0x00030000;
 	use_gl3 = use_gl3 && (GLOBAL_GET("rendering/quality/driver/driver_name") == "GLES3");
-	use_gl2 = !use_gl3;
-
-	if (gfx_init_func)
-		gfx_init_func(gfx_init_ud, use_gl2);
+	bool gl_initialization_error = false;
+
+	while (true) {
+		if (use_gl3) {
+			if (RasterizerGLES3::is_viable() == OK) {
+				if (gfx_init_func)
+					gfx_init_func(gfx_init_ud, false);
+				RasterizerGLES3::register_config();
+				RasterizerGLES3::make_current();
+				break;
+			} else {
+				if (GLOBAL_GET("rendering/quality/driver/driver_fallback") == "Best") {
+					p_video_driver = VIDEO_DRIVER_GLES2;
+					use_gl3 = false;
+					continue;
+				} else {
+					gl_initialization_error = true;
+					break;
+				}
+			}
+		} else {
+			if (RasterizerGLES2::is_viable() == OK) {
+				if (gfx_init_func)
+					gfx_init_func(gfx_init_ud, true);
+				RasterizerGLES2::register_config();
+				RasterizerGLES2::make_current();
+				break;
+			} else {
+				gl_initialization_error = true;
+				break;
+			}
+		}
+	}
 
-	if (use_gl2) {
-		RasterizerGLES2::register_config();
-		RasterizerGLES2::make_current();
-		video_driver_index = VIDEO_DRIVER_GLES2;
-	} else {
-		RasterizerGLES3::register_config();
-		RasterizerGLES3::make_current();
-		video_driver_index = VIDEO_DRIVER_GLES3;
+	if (gl_initialization_error) {
+		OS::get_singleton()->alert("Your device does not support any of the supported OpenGL versions.\n"
+								   "Please try updating your Android version.",
+				"Unable to initialize Video driver");
+		return ERR_UNAVAILABLE;
 	}
 
+	video_driver_index = p_video_driver;
+
 	visual_server = memnew(VisualServerRaster);
 	/*	if (get_render_thread_mode() != RENDER_THREAD_UNSAFE) {
 
 		visual_server = memnew(VisualServerWrapMT(visual_server, false));
 	};*/
+
 	visual_server->init();
 	//	visual_server->cursor_set_visible(false, 0);
 
diff --git a/platform/iphone/os_iphone.cpp b/platform/iphone/os_iphone.cpp
index a4538a6673..addef61ec7 100644
--- a/platform/iphone/os_iphone.cpp
+++ b/platform/iphone/os_iphone.cpp
@@ -99,8 +99,11 @@ int OSIPhone::get_current_video_driver() const {
 
 Error OSIPhone::initialize(const VideoMode &p_desired, int p_video_driver, int p_audio_driver) {
 
-	video_driver_index = p_video_driver; //this may be misleading
+	video_driver_index = VIDEO_DRIVER_GLES3;
 
+	if (RasterizerGLES3::is_viable() != OK) {
+		return ERR_UNAVAILABLE;
+	}
 	RasterizerGLES3::register_config();
 	RasterizerGLES3::make_current();
 
diff --git a/platform/javascript/os_javascript.cpp b/platform/javascript/os_javascript.cpp
index 5a8a05d4df..80699b0d32 100644
--- a/platform/javascript/os_javascript.cpp
+++ b/platform/javascript/os_javascript.cpp
@@ -652,23 +652,57 @@ Error OS_JavaScript::initialize(const VideoMode &p_desired, int p_video_driver,
 	attributes.alpha = false;
 	attributes.antialias = false;
 	ERR_FAIL_INDEX_V(p_video_driver, VIDEO_DRIVER_MAX, ERR_INVALID_PARAMETER);
-	switch (p_video_driver) {
-		case VIDEO_DRIVER_GLES3:
-			attributes.majorVersion = 2;
-			RasterizerGLES3::register_config();
-			RasterizerGLES3::make_current();
-			break;
-		case VIDEO_DRIVER_GLES2:
-			attributes.majorVersion = 1;
-			RasterizerGLES2::register_config();
-			RasterizerGLES2::make_current();
-			break;
+
+	bool gles3 = true;
+	if (p_video_driver == VIDEO_DRIVER_GLES2) {
+		gles3 = false;
+	}
+
+	bool gl_initialization_error = false;
+
+	while (true) {
+		if (gles3) {
+			if (RasterizerGLES3::is_viable() == OK) {
+				attributes.majorVersion = 2;
+				RasterizerGLES3::register_config();
+				RasterizerGLES3::make_current();
+				break;
+			} else {
+				if (GLOBAL_GET("rendering/quality/driver/driver_fallback") == "Best") {
+					p_video_driver = VIDEO_DRIVER_GLES2;
+					gles3 = false;
+					continue;
+				} else {
+					gl_initialization_error = true;
+					break;
+				}
+			}
+		} else {
+			if (RasterizerGLES2::is_viable() == OK) {
+				attributes.majorVersion = 1;
+				RasterizerGLES2::register_config();
+				RasterizerGLES2::make_current();
+				break;
+			} else {
+				gl_initialization_error = true;
+				break;
+			}
+		}
 	}
 
-	video_driver_index = p_video_driver;
 	EMSCRIPTEN_WEBGL_CONTEXT_HANDLE ctx = emscripten_webgl_create_context(NULL, &attributes);
-	ERR_EXPLAIN("WebGL " + itos(attributes.majorVersion) + ".0 not available");
-	ERR_FAIL_COND_V(emscripten_webgl_make_context_current(ctx) != EMSCRIPTEN_RESULT_SUCCESS, ERR_UNAVAILABLE);
+	if (emscripten_webgl_make_context_current(ctx) != EMSCRIPTEN_RESULT_SUCCESS) {
+		gl_initialization_error = true;
+	}
+
+	if (gl_initialization_error) {
+		OS::get_singleton()->alert("Your browser does not support any of the supported WebGL versions.\n"
+								   "Please update your browser version.",
+				"Unable to initialize Video driver");
+		return ERR_UNAVAILABLE;
+	}
+
+	video_driver_index = p_video_driver;
 
 	video_mode = p_desired;
 	// Can't fulfil fullscreen request during start-up due to browser security.
diff --git a/platform/osx/os_osx.mm b/platform/osx/os_osx.mm
index 41cfada723..79d7ec410a 100644
--- a/platform/osx/os_osx.mm
+++ b/platform/osx/os_osx.mm
@@ -1276,8 +1276,6 @@ Error OS_OSX::initialize(const VideoMode &p_desired, int p_video_driver, int p_a
 		ADD_ATTR2(NSOpenGLPFAOpenGLProfile, NSOpenGLProfileVersion3_2Core);
 	}
 
-	video_driver_index = p_video_driver;
-
 	ADD_ATTR2(NSOpenGLPFAColorSize, colorBits);
 
 	/*
@@ -1333,22 +1331,58 @@ Error OS_OSX::initialize(const VideoMode &p_desired, int p_video_driver, int p_a
 
 	/*** END OSX INITIALIZATION ***/
 
-	// only opengl support here...
+	bool gles3 = true;
 	if (p_video_driver == VIDEO_DRIVER_GLES2) {
-		RasterizerGLES2::register_config();
-		RasterizerGLES2::make_current();
-	} else {
-		RasterizerGLES3::register_config();
-		RasterizerGLES3::make_current();
+		gles3 = false;
 	}
 
+	bool editor = Engine::get_singleton()->is_editor_hint();
+	bool gl_initialization_error = false;
+
+	while (true) {
+		if (gles3) {
+			if (RasterizerGLES3::is_viable() == OK) {
+				RasterizerGLES3::register_config();
+				RasterizerGLES3::make_current();
+				break;
+			} else {
+				if (GLOBAL_GET("rendering/quality/driver/driver_fallback") == "Best" || editor) {
+					p_video_driver = VIDEO_DRIVER_GLES2;
+					gles3 = false;
+					continue;
+				} else {
+					gl_initialization_error = true;
+					break;
+				}
+			}
+		} else {
+			if (RasterizerGLES2::is_viable() == OK) {
+				RasterizerGLES2::register_config();
+				RasterizerGLES2::make_current();
+				break;
+			} else {
+				gl_initialization_error = true;
+				break;
+			}
+		}
+	}
+
+	if (gl_initialization_error) {
+		OS::get_singleton()->alert("Your video card driver does not support any of the supported OpenGL versions.\n"
+								   "Please update your drivers or if you have a very old or integrated GPU upgrade it.",
+				"Unable to initialize Video driver");
+		return ERR_UNAVAILABLE;
+	}
+
+	video_driver_index = p_video_driver;
+
 	visual_server = memnew(VisualServerRaster);
 	if (get_render_thread_mode() != RENDER_THREAD_UNSAFE) {
 
 		visual_server = memnew(VisualServerWrapMT(visual_server, get_render_thread_mode() == RENDER_SEPARATE_THREAD));
 	}
-	visual_server->init();
 
+	visual_server->init();
 	AudioDriverManager::initialize(p_audio_driver);
 
 	input = memnew(InputDefault);
diff --git a/platform/uwp/os_uwp.cpp b/platform/uwp/os_uwp.cpp
index 8549a44ce5..b6c3dcf9e0 100644
--- a/platform/uwp/os_uwp.cpp
+++ b/platform/uwp/os_uwp.cpp
@@ -187,12 +187,78 @@ Error OSUWP::initialize(const VideoMode &p_desired, int p_video_driver, int p_au
 	main_loop = NULL;
 	outside = true;
 
+	ContextEGL::Driver opengl_api_type = ContextEGL::GLES_2_0;
+
 	if (p_video_driver == VIDEO_DRIVER_GLES2) {
-		gl_context = memnew(ContextEGL(window, ContextEGL::GLES_2_0));
-	} else {
-		gl_context = memnew(ContextEGL(window, ContextEGL::GLES_3_0));
+		opengl_api_type = ContextEGL::GLES_2_0;
+	}
+
+	bool gl_initialization_error = false;
+
+	gl_context = NULL;
+	while (!gl_context) {
+		gl_context = memnew(ContextEGL(window, opengl_api_type));
+
+		if (gl_context->initialize() != OK) {
+			memdelete(gl_context);
+			gl_context = NULL;
+
+			if (GLOBAL_GET("rendering/quality/driver/driver_fallback") == "Best") {
+				if (p_video_driver == VIDEO_DRIVER_GLES2) {
+					gl_initialization_error = true;
+					break;
+				}
+
+				p_video_driver = VIDEO_DRIVER_GLES2;
+				opengl_api_type = ContextEGL::GLES_2_0;
+			} else {
+				gl_initialization_error = true;
+				break;
+			}
+		}
+	}
+
+	while (true) {
+		if (opengl_api_type == ContextEGL::GLES_3_0) {
+			if (RasterizerGLES3::is_viable() == OK) {
+				RasterizerGLES3::register_config();
+				RasterizerGLES3::make_current();
+				break;
+			} else {
+				if (GLOBAL_GET("rendering/quality/driver/driver_fallback") == "Best" || editor) {
+					p_video_driver = VIDEO_DRIVER_GLES2;
+					opengl_api_type = ContextEGL::GLES_2_0;
+					continue;
+				} else {
+					gl_initialization_error = true;
+					break;
+				}
+			}
+		}
+
+		if (opengl_api_type == ContextEGL::GLES_2_0) {
+			if (RasterizerGLES2::is_viable() == OK) {
+				RasterizerGLES2::register_config();
+				RasterizerGLES2::make_current();
+				break;
+			} else {
+				gl_initialization_error = true;
+				break;
+			}
+		}
+	}
+
+	if (gl_initialization_error) {
+		OS::get_singleton()->alert("Your video card driver does not support any of the supported OpenGL versions.\n"
+								   "Please update your drivers or if you have a very old or integrated GPU upgrade it.",
+				"Unable to initialize Video driver");
+		return ERR_UNAVAILABLE;
 	}
-	gl_context->initialize();
+
+	video_driver_index = p_video_driver;
+	gl_context->make_current();
+	gl_context->set_use_vsync(video_mode.use_vsync);
+
 	VideoMode vm;
 	vm.width = gl_context->get_window_width();
 	vm.height = gl_context->get_window_height();
@@ -230,19 +296,6 @@ Error OSUWP::initialize(const VideoMode &p_desired, int p_video_driver, int p_au
 
 	set_video_mode(vm);
 
-	gl_context->make_current();
-
-	if (p_video_driver == VIDEO_DRIVER_GLES2) {
-		RasterizerGLES2::register_config();
-		RasterizerGLES2::make_current();
-	} else {
-		RasterizerGLES3::register_config();
-		RasterizerGLES3::make_current();
-	}
-	gl_context->set_use_vsync(vm.use_vsync);
-
-	video_driver_index = p_video_driver;
-
 	visual_server = memnew(VisualServerRaster);
 	// FIXME: Reimplement threaded rendering? Or remove?
 	/*
@@ -253,7 +306,6 @@ Error OSUWP::initialize(const VideoMode &p_desired, int p_video_driver, int p_au
 	*/
 
 	visual_server->init();
-
 	input = memnew(InputDefault);
 
 	joypad = ref new JoypadUWP(input);
diff --git a/platform/windows/context_gl_win.cpp b/platform/windows/context_gl_win.cpp
index 59435b04ea..794f6df31f 100644
--- a/platform/windows/context_gl_win.cpp
+++ b/platform/windows/context_gl_win.cpp
@@ -108,28 +108,24 @@ Error ContextGL_Win::initialize() {
 
 	hDC = GetDC(hWnd);
 	if (!hDC) {
-		MessageBox(NULL, "Can't Create A GL Device Context.", "ERROR", MB_OK | MB_ICONEXCLAMATION);
 		return ERR_CANT_CREATE; // Return FALSE
 	}
 
 	pixel_format = ChoosePixelFormat(hDC, &pfd);
 	if (!pixel_format) // Did Windows Find A Matching Pixel Format?
 	{
-		MessageBox(NULL, "Can't Find A Suitable pixel_format.", "ERROR", MB_OK | MB_ICONEXCLAMATION);
 		return ERR_CANT_CREATE; // Return FALSE
 	}
 
 	BOOL ret = SetPixelFormat(hDC, pixel_format, &pfd);
 	if (!ret) // Are We Able To Set The Pixel Format?
 	{
-		MessageBox(NULL, "Can't Set The pixel_format.", "ERROR", MB_OK | MB_ICONEXCLAMATION);
 		return ERR_CANT_CREATE; // Return FALSE
 	}
 
 	hRC = wglCreateContext(hDC);
 	if (!hRC) // Are We Able To Get A Rendering Context?
 	{
-		MessageBox(NULL, "Can't Create A Temporary GL Rendering Context.", "ERROR", MB_OK | MB_ICONEXCLAMATION);
 		return ERR_CANT_CREATE; // Return FALSE
 	}
 
@@ -151,7 +147,6 @@ Error ContextGL_Win::initialize() {
 
 		if (wglCreateContextAttribsARB == NULL) //OpenGL 3.0 is not supported
 		{
-			MessageBox(NULL, "Cannot get Proc Address for CreateContextAttribs", "ERROR", MB_OK | MB_ICONEXCLAMATION);
 			wglDeleteContext(hRC);
 			return ERR_CANT_CREATE;
 		}
@@ -159,7 +154,6 @@ Error ContextGL_Win::initialize() {
 		HGLRC new_hRC = wglCreateContextAttribsARB(hDC, 0, attribs);
 		if (!new_hRC) {
 			wglDeleteContext(hRC);
-			MessageBox(NULL, "Can't Create An OpenGL 3.3 Rendering Context.", "ERROR", MB_OK | MB_ICONEXCLAMATION);
 			return ERR_CANT_CREATE; // Return false
 		}
 		wglMakeCurrent(hDC, NULL);
@@ -168,7 +162,6 @@ Error ContextGL_Win::initialize() {
 
 		if (!wglMakeCurrent(hDC, hRC)) // Try To Activate The Rendering Context
 		{
-			MessageBox(NULL, "Can't Activate The GL 3.3 Rendering Context.", "ERROR", MB_OK | MB_ICONEXCLAMATION);
 			return ERR_CANT_CREATE; // Return FALSE
 		}
 	}
diff --git a/platform/windows/os_windows.cpp b/platform/windows/os_windows.cpp
index fa8717a4b8..03f2199954 100644
--- a/platform/windows/os_windows.cpp
+++ b/platform/windows/os_windows.cpp
@@ -1273,21 +1273,74 @@ Error OS_Windows::initialize(const VideoMode &p_desired, int p_video_driver, int
 	}
 
 #if defined(OPENGL_ENABLED)
+
+	bool gles3_context = true;
 	if (p_video_driver == VIDEO_DRIVER_GLES2) {
-		gl_context = memnew(ContextGL_Win(hWnd, false));
-		gl_context->initialize();
+		gles3_context = false;
+	}
 
-		RasterizerGLES2::register_config();
-		RasterizerGLES2::make_current();
-	} else {
-		gl_context = memnew(ContextGL_Win(hWnd, true));
-		gl_context->initialize();
+	bool editor = Engine::get_singleton()->is_editor_hint();
+	bool gl_initialization_error = false;
+
+	gl_context = NULL;
+	while (!gl_context) {
+		gl_context = memnew(ContextGL_Win(hWnd, gles3_context));
+
+		if (gl_context->initialize() != OK) {
+			memdelete(gl_context);
+			gl_context = NULL;
+
+			if (GLOBAL_GET("rendering/quality/driver/driver_fallback") == "Best" || editor) {
+				if (p_video_driver == VIDEO_DRIVER_GLES2) {
+					gl_initialization_error = true;
+					break;
+				}
 
-		RasterizerGLES3::register_config();
-		RasterizerGLES3::make_current();
+				p_video_driver = VIDEO_DRIVER_GLES2;
+				gles3_context = false;
+			} else {
+				gl_initialization_error = true;
+				break;
+			}
+		}
+	}
+
+	while (true) {
+		if (gles3_context) {
+			if (RasterizerGLES3::is_viable() == OK) {
+				RasterizerGLES3::register_config();
+				RasterizerGLES3::make_current();
+				break;
+			} else {
+				if (GLOBAL_GET("rendering/quality/driver/driver_fallback") == "Best" || editor) {
+					p_video_driver = VIDEO_DRIVER_GLES2;
+					gles3_context = false;
+					continue;
+				} else {
+					gl_initialization_error = true;
+					break;
+				}
+			}
+		} else {
+			if (RasterizerGLES2::is_viable() == OK) {
+				RasterizerGLES2::register_config();
+				RasterizerGLES2::make_current();
+				break;
+			} else {
+				gl_initialization_error = true;
+				break;
+			}
+		}
+	}
+
+	if (gl_initialization_error) {
+		OS::get_singleton()->alert("Your video card driver does not support any of the supported OpenGL versions.\n"
+								   "Please update your drivers or if you have a very old or integrated GPU upgrade it.",
+				"Unable to initialize Video driver");
+		return ERR_UNAVAILABLE;
 	}
 
-	video_driver_index = p_video_driver; // FIXME TODO - FIX IF DRIVER DETECTION HAPPENS AND GLES2 MUST BE USED
+	video_driver_index = p_video_driver;
 
 	gl_context->set_use_vsync(video_mode.use_vsync);
 #endif
diff --git a/platform/x11/context_gl_x11.cpp b/platform/x11/context_gl_x11.cpp
index 5a239e326b..8c1869a1f1 100644
--- a/platform/x11/context_gl_x11.cpp
+++ b/platform/x11/context_gl_x11.cpp
@@ -116,9 +116,14 @@ Error ContextGL_X11::initialize() {
 	};
 
 	int fbcount;
-	GLXFBConfig fbconfig;
+	GLXFBConfig fbconfig = 0;
 	XVisualInfo *vi = NULL;
 
+	XSetWindowAttributes swa;
+	swa.event_mask = StructureNotifyMask;
+	swa.border_pixel = 0;
+	unsigned long valuemask = CWBorderPixel | CWColormap | CWEventMask;
+
 	if (OS::get_singleton()->is_layered_allowed()) {
 		GLXFBConfig *fbc = glXChooseFBConfig(x11_display, DefaultScreen(x11_display), visual_attribs_layered, &fbcount);
 		ERR_FAIL_COND_V(!fbc, ERR_UNCONFIGURED);
@@ -142,16 +147,10 @@ Error ContextGL_X11::initialize() {
 		}
 		ERR_FAIL_COND_V(!fbconfig, ERR_UNCONFIGURED);
 
-		XSetWindowAttributes swa;
-
-		swa.colormap = XCreateColormap(x11_display, RootWindow(x11_display, vi->screen), vi->visual, AllocNone);
-		swa.border_pixel = 0;
 		swa.background_pixmap = None;
 		swa.background_pixel = 0;
 		swa.border_pixmap = None;
-		swa.event_mask = StructureNotifyMask;
-
-		x11_window = XCreateWindow(x11_display, RootWindow(x11_display, vi->screen), 0, 0, OS::get_singleton()->get_video_mode().width, OS::get_singleton()->get_video_mode().height, 0, vi->depth, InputOutput, vi->visual, CWBorderPixel | CWColormap | CWEventMask | CWBackPixel, &swa);
+		valuemask |= CWBackPixel;
 
 	} else {
 		GLXFBConfig *fbc = glXChooseFBConfig(x11_display, DefaultScreen(x11_display), visual_attribs, &fbcount);
@@ -160,42 +159,21 @@ Error ContextGL_X11::initialize() {
 		vi = glXGetVisualFromFBConfig(x11_display, fbc[0]);
 
 		fbconfig = fbc[0];
-
-		XSetWindowAttributes swa;
-
-		swa.colormap = XCreateColormap(x11_display, RootWindow(x11_display, vi->screen), vi->visual, AllocNone);
-		swa.border_pixel = 0;
-		swa.event_mask = StructureNotifyMask;
-
-		x11_window = XCreateWindow(x11_display, RootWindow(x11_display, vi->screen), 0, 0, OS::get_singleton()->get_video_mode().width, OS::get_singleton()->get_video_mode().height, 0, vi->depth, InputOutput, vi->visual, CWBorderPixel | CWColormap | CWEventMask, &swa);
 	}
 
-	ERR_FAIL_COND_V(!x11_window, ERR_UNCONFIGURED);
-	set_class_hint(x11_display, x11_window);
-	XMapWindow(x11_display, x11_window);
-
-	int (*oldHandler)(Display *, XErrorEvent *) =
-			XSetErrorHandler(&ctxErrorHandler);
+	int (*oldHandler)(Display *, XErrorEvent *) = XSetErrorHandler(&ctxErrorHandler);
 
 	switch (context_type) {
-		case GLES_2_0_COMPATIBLE:
 		case OLDSTYLE: {
+
 			p->glx_context = glXCreateContext(x11_display, vi, 0, GL_TRUE);
+			ERR_FAIL_COND_V(!p->glx_context, ERR_UNCONFIGURED);
 		} break;
-		/*
-		case ContextType::GLES_2_0_COMPATIBLE: {
-
-			static int context_attribs[] = {
-				GLX_CONTEXT_MAJOR_VERSION_ARB, 3,
-				GLX_CONTEXT_MINOR_VERSION_ARB, 0,
-				None
-			};
+		case GLES_2_0_COMPATIBLE: {
 
-			p->glx_context = glXCreateContextAttribsARB(x11_display, fbconfig, NULL, true, context_attribs);
-			ERR_EXPLAIN("Could not obtain an OpenGL 3.0 context!");
+			p->glx_context = glXCreateNewContext(x11_display, fbconfig, GLX_RGBA_TYPE, 0, true);
 			ERR_FAIL_COND_V(!p->glx_context, ERR_UNCONFIGURED);
 		} break;
-		*/
 		case GLES_3_0_COMPATIBLE: {
 
 			static int context_attribs[] = {
@@ -207,24 +185,22 @@ Error ContextGL_X11::initialize() {
 			};
 
 			p->glx_context = glXCreateContextAttribsARB(x11_display, fbconfig, NULL, true, context_attribs);
-			ERR_EXPLAIN("Could not obtain an OpenGL 3.3 context!");
 			ERR_FAIL_COND_V(ctxErrorOccurred || !p->glx_context, ERR_UNCONFIGURED);
 		} break;
 	}
 
+	swa.colormap = XCreateColormap(x11_display, RootWindow(x11_display, vi->screen), vi->visual, AllocNone);
+	x11_window = XCreateWindow(x11_display, RootWindow(x11_display, vi->screen), 0, 0, OS::get_singleton()->get_video_mode().width, OS::get_singleton()->get_video_mode().height, 0, vi->depth, InputOutput, vi->visual, valuemask, &swa);
+
+	ERR_FAIL_COND_V(!x11_window, ERR_UNCONFIGURED);
+	set_class_hint(x11_display, x11_window);
+	XMapWindow(x11_display, x11_window);
+
 	XSync(x11_display, False);
 	XSetErrorHandler(oldHandler);
 
 	glXMakeCurrent(x11_display, x11_window, p->glx_context);
 
-	/*
-	glWrapperInit(wrapper_get_proc_address);
-	glFlush();
-
-	glXSwapBuffers(x11_display,x11_window);
-*/
-	//glXMakeCurrent(x11_display, None, NULL);
-
 	XFree(vi);
 
 	return OK;
@@ -297,7 +273,6 @@ ContextGL_X11::ContextGL_X11(::Display *p_x11_display, ::Window &p_x11_window, c
 ContextGL_X11::~ContextGL_X11() {
 	release_current();
 	glXDestroyContext(x11_display, p->glx_context);
-
 	memdelete(p);
 }
 
diff --git a/platform/x11/os_x11.cpp b/platform/x11/os_x11.cpp
index ca9fd68412..0f6718b718 100644
--- a/platform/x11/os_x11.cpp
+++ b/platform/x11/os_x11.cpp
@@ -274,21 +274,70 @@ Error OS_X11::initialize(const VideoMode &p_desired, int p_video_driver, int p_a
 		opengl_api_type = ContextGL_X11::GLES_2_0_COMPATIBLE;
 	}
 
-	context_gl = memnew(ContextGL_X11(x11_display, x11_window, current_videomode, opengl_api_type));
-	context_gl->initialize();
+	bool editor = Engine::get_singleton()->is_editor_hint();
+	bool gl_initialization_error = false;
 
-	switch (opengl_api_type) {
-		case ContextGL_X11::GLES_2_0_COMPATIBLE: {
-			RasterizerGLES2::register_config();
-			RasterizerGLES2::make_current();
-		} break;
-		case ContextGL_X11::GLES_3_0_COMPATIBLE: {
-			RasterizerGLES3::register_config();
-			RasterizerGLES3::make_current();
-		} break;
+	context_gl = NULL;
+	while (!context_gl) {
+		context_gl = memnew(ContextGL_X11(x11_display, x11_window, current_videomode, opengl_api_type));
+
+		if (context_gl->initialize() != OK) {
+			memdelete(context_gl);
+			context_gl = NULL;
+
+			if (GLOBAL_GET("rendering/quality/driver/driver_fallback") == "Best" || editor) {
+				if (p_video_driver == VIDEO_DRIVER_GLES2) {
+					gl_initialization_error = true;
+					break;
+				}
+
+				p_video_driver = VIDEO_DRIVER_GLES2;
+				opengl_api_type = ContextGL_X11::GLES_2_0_COMPATIBLE;
+			} else {
+				gl_initialization_error = true;
+				break;
+			}
+		}
+	}
+
+	while (true) {
+		if (opengl_api_type == ContextGL_X11::GLES_3_0_COMPATIBLE) {
+			if (RasterizerGLES3::is_viable() == OK) {
+				RasterizerGLES3::register_config();
+				RasterizerGLES3::make_current();
+				break;
+			} else {
+				if (GLOBAL_GET("rendering/quality/driver/driver_fallback") == "Best" || editor) {
+					p_video_driver = VIDEO_DRIVER_GLES2;
+					opengl_api_type = ContextGL_X11::GLES_2_0_COMPATIBLE;
+					continue;
+				} else {
+					gl_initialization_error = true;
+					break;
+				}
+			}
+		}
+
+		if (opengl_api_type == ContextGL_X11::GLES_2_0_COMPATIBLE) {
+			if (RasterizerGLES2::is_viable() == OK) {
+				RasterizerGLES2::register_config();
+				RasterizerGLES2::make_current();
+				break;
+			} else {
+				gl_initialization_error = true;
+				break;
+			}
+		}
+	}
+
+	if (gl_initialization_error) {
+		OS::get_singleton()->alert("Your video card driver does not support any of the supported OpenGL versions.\n"
+								   "Please update your drivers or if you have a very old or integrated GPU upgrade it.",
+				"Unable to initialize Video driver");
+		return ERR_UNAVAILABLE;
 	}
 
-	video_driver_index = p_video_driver; // FIXME TODO - FIX IF DRIVER DETECTION HAPPENS AND GLES2 MUST BE USED
+	video_driver_index = p_video_driver;
 
 	context_gl->set_use_vsync(current_videomode.use_vsync);
 
@@ -339,8 +388,6 @@ Error OS_X11::initialize(const VideoMode &p_desired, int p_video_driver, int p_a
 		set_window_always_on_top(true);
 	}
 
-	AudioDriverManager::initialize(p_audio_driver);
-
 	ERR_FAIL_COND_V(!visual_server, ERR_UNAVAILABLE);
 	ERR_FAIL_COND_V(x11_window == 0, ERR_UNAVAILABLE);
 
@@ -510,6 +557,8 @@ Error OS_X11::initialize(const VideoMode &p_desired, int p_video_driver, int p_a
 
 	visual_server->init();
 
+	AudioDriverManager::initialize(p_audio_driver);
+
 	input = memnew(InputDefault);
 
 	window_has_focus = true; // Set focus to true at init