Add a Troubleshooting section to Exporting packs, patches and mods

- Mention that the pack must be loaded early enough to have an effect.
- Mention load order being important.
- Mention ZIP format throughout the page, as it can be used in the same
  way as PCK files.
- Link to Run-time resource loading and saving tutorial as an alternative.

tutorials/export/exporting_pcks.rst

@@ -6,7 +6,7 @@ Exporting packs, patches, and mods
 Use cases
 ---------
 
-Oftentimes one would like to add functionality to one's game after it has been
+Oftentimes, one would like to add functionality to one's game after it has been
 deployed.
 
 Examples of this include...
@@ -18,11 +18,11 @@ Examples of this include...
 These tools help developers to extend their development beyond the initial
 release.
 
-Overview of PCK files
----------------------
+Overview of PCK/ZIP files
+-------------------------
 
 Godot enables this via a feature called **resource packs** (PCK files,
-with extension ``.pck``).
+with the ``.pck`` extension, or ZIP files).
 
 **Advantages:**
 
@@ -35,9 +35,9 @@ with extension ``.pck``).
 
 The first part of using them involves exporting and delivering the project to
 players. Then, when one wants to add functionality or content later on, they
-just deliver the updates via PCK files to the users.
+just deliver the updates via PCK/ZIP files to the users.
 
-PCK files usually contain, but are not limited to:
+PCK/ZIP files usually contain, but are not limited to:
 
 - scripts
 - scenes
@@ -48,21 +48,35 @@ PCK files usually contain, but are not limited to:
 - music
 - any other asset suitable for import into the game
 
-The PCK files can even be an entirely different Godot project, which the
+The PCK/ZIP files can even be an entirely different Godot project, which the
 original game loads in at runtime.
 
+It is possible to load both PCK and ZIP files as additional packs at the same time.
+See :ref:`doc_exporting_projects_pck_versus_zip` for a comparison of the two formats.
+
+.. seealso::
+
+    If you want to load loose files at runtime (not packed in a PCK or ZIP by Godot),
+    consider using :ref:`doc_runtime_loading_and_saving` instead.
+    This is useful for loading user-generated content that is not made with Godot,
+    without requiring users to pack their mods into a specific file format.
+
+    The downside of this approach is that it's less transparent to the game logic,
+    as it will not benefit from the same resource management as PCK/ZIP files.
+
 Generating PCK files
 --------------------
 
-In order to pack all resources of a project into a PCK file open the project
-and go to Project/Export and click on "Export PCK/Zip". Also make sure to have
-an export template selected while doing so.
+In order to pack all resources of a project into a PCK file, open the project
+and go to **Project > Export** and click on **Export PCK/ZIP**. Also, make sure
+to have an export preset selected while doing so.
 
 .. image:: img/export_pck.webp
 
-Another method would be to :ref:`export from the command line <doc_command_line_tutorial_exporting>`.
-If the output file ends with a PCK or ZIP file extension, then the export
-process will build that type of file for the chosen platform.
+Another method would be to :ref:`export from the command line <doc_command_line_tutorial_exporting>`
+with ``--export-pack``. The output file must with a ``.pck`` or ``.zip``
+file extension. The export process will build that type of file for the
+chosen platform.
 
 .. note::
 
@@ -86,19 +100,19 @@ process will build that type of file for the chosen platform.
        use a tool-build of the engine (for security), so it's best to keep
        the modding tool and game separate.
 
-Opening PCK files at runtime
-----------------------------
+Opening PCK or ZIP files at runtime
+-----------------------------------
 
-To import a PCK file, one uses the ProjectSettings singleton. The following
-example expects a “mod.pck” file in the directory of the games executable.
-The PCK file contains a “mod_scene.tscn” test scene in its root.
+To load a PCK or ZIP file, one uses the ProjectSettings singleton. The following
+example expects a ``mod.pck`` file in the directory of the game's executable.
+The PCK or ZIP file contains a ``mod_scene.tscn`` test scene in its root.
 
 .. tabs::
  .. code-tab:: gdscript GDScript
 
     func _your_function():
         # This could fail if, for example, mod.pck cannot be found.
-        var success = ProjectSettings.load_resource_pack("res://mod.pck")
+        var success = ProjectSettings.load_resource_pack(OS.get_executable_path().get_base_dir().path_join("mod.pck"))
 
         if success:
             # Now one can use the assets as if they had them in the project from the start.
@@ -109,7 +123,7 @@ The PCK file contains a “mod_scene.tscn” test scene in its root.
     private void YourFunction()
     {
         // This could fail if, for example, mod.pck cannot be found.
-        var success = ProjectSettings.LoadResourcePack("res://mod.pck");
+        var success = ProjectSettings.LoadResourcePack(OS.get_executable_path().get_base_dir().path_join("mod.pck));
 
         if (success)
         {
@@ -120,20 +134,39 @@ The PCK file contains a “mod_scene.tscn” test scene in its root.
 
 .. warning::
 
-    By default, if you import a file with the same file path/name as one you already have in your
-    project, the imported one will replace it. This is something to watch out for when
-    creating DLC or mods. You can solve this problem by using a tool that isolates mods to a specific mods subfolder.
-    However, it is also a way of creating patches for one's own game. A
-    PCK file of this kind can fix the content of a previously loaded PCK.
+    By default, if you import a file with the same file path/name as one you
+    already have in your project, the imported one will replace it. This is
+    something to watch out for when creating DLC or mods. You can solve this
+    problem by using a tool that isolates mods to a specific mods subfolder.
+
+    However, it is also a way of creating patches for one's own game. A PCK/ZIP
+    file of this kind can fix the content of a previously loaded PCK/ZIP
+    (therefore, the order in which packs are loaded matters).
 
     To opt out of this behavior, pass ``false`` as the second argument to
     :ref:`ProjectSettings.load_resource_pack() <class_ProjectSettings_method_load_resource_pack>`.
 
 .. note::
+
     For a C# project, you need to build the DLL and place it in the project directory first.
     Then, before loading the resource pack, you need to load its DLL as follows:
     ``Assembly.LoadFile("mod.dll")``
 
+Troubleshooting
+^^^^^^^^^^^^^^^
+
+If you are loading a resource pack and are not noticing any changes, it may be
+due to the pack being loaded too late. This is particularly the case with menu
+scenes that may preload other scenes using
+:ref:`preload() <class_@GDScript_method_preload>`. This means that loading
+a pack in the menu will not affect the other scene that was already preloaded.
+
+To avoid this, you need to load the pack as early as possible.
+To do so, create a new :ref:`autoload <doc_singletons_autoload>` script and
+call :ref:`ProjectSettings.load_resource_pack() <class_ProjectSettings_method_load_resource_pack>`
+in the autoload script's ``_init()`` function, rather than ``_enter_tree()``
+or ``_ready()``.
+
 Summary
 -------
 

tutorials/export/exporting_projects.rst

@@ -220,6 +220,8 @@ the command:
     See :ref:`doc_command_line_tutorial` for more information about using Godot
     from the command line.
 
+.. _doc_exporting_projects_pck_versus_zip:
+
 PCK versus ZIP pack file formats
 --------------------------------