Use GLES2 by default in the project manager

This only applies to the project manager instance, what driver is used is otherwise
still defined by the project settings for a running game/editor.

Should help users who have issues with buggy GLES3 drivers to still use the project
manager to create and edit GLES2 projects.

editor/project_manager.cpp

@@ -52,6 +52,11 @@
 #include "scene/gui/texture_rect.h"
 #include "scene/gui/tool_button.h"
 
+// Used to test for GLES3 support.
+#ifndef SERVER_ENABLED
+#include "drivers/gles3/rasterizer_gles3.h"
+#endif
+
 static inline String get_project_key_from_path(const String &dir) {
 	return dir.replace("/", "::");
 }
@@ -878,7 +883,14 @@ public:
 		rasterizer_container->add_child(rshb);
 		rasterizer_button_group.instance();
 
-		bool is_gles3 = OS::get_singleton()->get_current_video_driver() == OS::VIDEO_DRIVER_GLES3;
+		// Enable GLES3 by default as it's the default value for the project setting.
+#ifndef SERVER_ENABLED
+		bool gles3_viable = RasterizerGLES3::is_viable() == OK;
+#else
+		// Whatever, project manager isn't even used in headless builds.
+		bool gles3_viable = false;
+#endif
+
 		Container *rvb = memnew(VBoxContainer);
 		rvb->set_h_size_flags(SIZE_EXPAND_FILL);
 		rshb->add_child(rvb);
@@ -886,9 +898,14 @@ public:
 		rs_button->set_button_group(rasterizer_button_group);
 		rs_button->set_text(TTR("OpenGL ES 3.0"));
 		rs_button->set_meta("driver_name", "GLES3");
-		rs_button->set_pressed(is_gles3);
+		rs_button->set_pressed(gles3_viable);
+		// If GLES3 can't be used, don't let users shoot themselves in the foot.
+		rs_button->set_disabled(!gles3_viable);
 		rvb->add_child(rs_button);
 		l = memnew(Label);
+		l->set_text(TTR("Not supported by your GPU drivers."));
+		rvb->add_child(l);
+		l = memnew(Label);
 		l->set_text(TTR("Higher visual quality\nAll features available\nIncompatible with older hardware\nNot recommended for web games"));
 		rvb->add_child(l);
 
@@ -901,7 +918,7 @@ public:
 		rs_button->set_button_group(rasterizer_button_group);
 		rs_button->set_text(TTR("OpenGL ES 2.0"));
 		rs_button->set_meta("driver_name", "GLES2");
-		rs_button->set_pressed(!is_gles3);
+		rs_button->set_pressed(!gles3_viable);
 		rvb->add_child(rs_button);
 		l = memnew(Label);
 		l->set_text(TTR("Lower visual quality\nSome features not available\nWorks on most hardware\nRecommended for web games"));

main/main.cpp

@@ -1022,7 +1022,11 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 	GLOBAL_DEF("rendering/quality/driver/driver_name", "GLES3");
 	ProjectSettings::get_singleton()->set_custom_property_info("rendering/quality/driver/driver_name", PropertyInfo(Variant::STRING, "rendering/quality/driver/driver_name", PROPERTY_HINT_ENUM, "GLES2,GLES3"));
 	if (video_driver == "") {
-		video_driver = GLOBAL_GET("rendering/quality/driver/driver_name");
+		if (project_manager) {
+			video_driver = "GLES2"; // Force GLES2 for maximum compatibility, unless specified from command line.
+		} else {
+			video_driver = GLOBAL_GET("rendering/quality/driver/driver_name");
+		}
 	}
 
 	GLOBAL_DEF("rendering/quality/driver/fallback_to_gles2", false);