Write out render_mode even when mode is set to default in VisualShaders

scene/resources/visual_shader.cpp

@@ -2183,11 +2183,17 @@ void VisualShader::_update_shader() const {
 			const String temp = String(info.name);
 
 			if (!info.options.is_empty()) {
+				if (!render_mode.is_empty()) {
+					render_mode += ", ";
+				}
+				// Always write out a render_mode for the enumerated modes as having no render mode is not always
+				// the same as the default. i.e. for depth_draw_opaque, the render mode has to be declared for it
+				// to work properly, no render mode is an invalid option.
 				if (modes.has(temp) && modes[temp] < info.options.size()) {
-					if (!render_mode.is_empty()) {
-						render_mode += ", ";
-					}
 					render_mode += temp + "_" + info.options[modes[temp]];
+				} else {
+					// Use the default.
+					render_mode += temp + "_" + info.options[0];
 				}
 			} else if (flags.has(temp)) {
 				flag_names.push_back(temp);