godot-docs/development/compiling/compiling_with_mono.rst

.. _doc_compiling_with_mono:

Compiling with Mono
===================

.. highlight:: shell

Requirements
------------

- Mono 5.12.0 or greater
- MSBuild
- NuGet
- pkg-config

You may need to import necessary certificates for NuGet to perform HTTPS
requests. You can do this with the following command (on Windows, you can run it
from the Mono command line prompt)::

    mozroots --import --sync

Environment variables
---------------------

By default, SCons will try to find Mono in the Windows Registry on Windows or
via ``pkg-config`` on other platforms. You can specify a different installation
directory by passing the ``mono_prefix`` command-line option to SCons; e.g.
``scons [...] mono_prefix=%ProgramFiles%/Mono``.

This is the directory that contains the subdirectories ``include`` and ``lib``.

Enable the Mono module
----------------------

By default, the Mono module is disabled when building. To enable it, add the
option ``module_mono_enabled=yes`` to the SCons command line.

Generate the glue
-------------------

Glue sources are the wrapper functions that will be called by managed methods.
These source files must be generated before building your final binaries. In
order to generate them, first, you must build a temporary Godot binary with the
options ``tools=yes`` and ``mono_glue=no``::

    scons p=<platform> tools=yes module_mono_enabled=yes mono_glue=no

After the build finishes, you need to run the compiled executable with the
parameter ``--generate-mono-glue`` followed by the path to an output directory.
This path must be ``modules/mono/glue`` in the Godot directory::

    <godot_binary> --generate-mono-glue modules/mono/glue

This command will tell Godot to generate the file ``modules/mono/glue/mono_glue.gen.cpp``
and the C# solution for the Godot API at ``modules/mono/glue/Managed/Generated``.
Once these files are generated, you can build Godot for all the desired targets
without having to repeat this process.

``<godot_binary>`` refers to the tools binary you compiled above with the Mono
module enabled. Its exact name will differ based on your system and
configuration, but should be of the form
``bin/godot.<platform>.tools.<bits>.mono``, e.g. ``bin/godot.x11.tools.64.mono``
or ``bin/godot.windows.tools.64.exe``. Be especially aware of the **.mono**
suffix! If you've previously compiled Godot without Mono support, you might have
similarly named binaries without this suffix. These binaries can't be used to
generate the Mono glue.

Notes
^^^^^
- **Do not build your final binaries with** ``mono_glue=no``.
  This disables C# scripting. This option must be used only for the temporary
  binary that will generate the glue. Godot will print a warning at startup if
  it was built without the glue sources.
- The glue sources must be regenerated every time the ClassDB-registered API
  changes. That is, for example, when a new method is registered to the
  scripting API or one of the parameters of such a method changes.
  Godot will print an error at startup if there is an API mismatch
  between ClassDB and the glue sources.


Rebuild with Mono glue
----------------------

Once you have generated the Mono glue, you can build the final binary with
``mono_glue=yes``. This is the default value for ``mono_glue``, so you can also
omit it. To build a Mono-enabled editor::

    scons p=<platform> tools=yes module_mono_enabled=yes mono_glue=yes

And Mono-enabled export templates::

    scons p=<platform> tools=no module_mono_enabled=yes mono_glue=yes

If everything went well, apart from the normal output, SCons should have created
the following files in the ``bin`` directory:

- If you're not linking the Mono runtime statically, the build script will place
  the Mono runtime shared library (``monosgen-2.0``) next to the Godot
  binary in the output directory. Make sure to include this library when
  distributing Godot. When targeting Android, no extra steps are required as
  this library is automatically copied to ``#platform/android/java/libs`` and
  Gradle takes care of the rest.
- Unlike "classical" Godot builds, when building with the Mono module enabled
  (and depending on the target platform), a data directory may be created both
  for the editor and for export templates. This directory is important for
  proper functioning and must be distributed together with Godot.
  More details about this directory in
  :ref:`Data directory<compiling_with_mono_data_directory>`.

Examples
--------

Example (Windows)
^^^^^^^^^^^^^^^^^
::

    # Build temporary binary
    scons p=windows tools=yes module_mono_enabled=yes mono_glue=no
    # Generate glue sources
    bin\godot.windows.tools.64.mono --generate-mono-glue modules/mono/glue

    ### Build binaries normally
    # Editor
    scons p=windows target=release_debug tools=yes module_mono_enabled=yes
    # Export templates
    scons p=windows target=debug tools=no module_mono_enabled=yes
    scons p=windows target=release tools=no module_mono_enabled=yes

Example (X11)
^^^^^^^^^^^^^
::

    # Build temporary binary
    scons p=x11 tools=yes module_mono_enabled=yes mono_glue=no
    # Generate glue sources
    bin/godot.x11.tools.64.mono --generate-mono-glue modules/mono/glue

    ### Build binaries normally
    # Editor
    scons p=x11 target=release_debug tools=yes module_mono_enabled=yes
    # Export templates
    scons p=x11 target=debug tools=no module_mono_enabled=yes
    scons p=x11 target=release tools=no module_mono_enabled=yes

.. _compiling_with_mono_data_directory:

Data directory
--------------

The data directory is a dependency for Godot binaries built with the Mono module
enabled. It contains important files for the correct functioning of Godot. It
must be distributed together with the Godot executable.

.. note:: The information below doesn't apply to Android, as there is
          no data directory for that platform.

Export templates
^^^^^^^^^^^^^^^^

The name of the data directory for an export template differs based on the
configuration it was built with. The format is
``data.mono.<platform>.<bits>.<target>``, e.g. ``data.mono.x11.32.debug`` or
``data.mono.windows.64.release``.

This directory must be placed with its original name next to the Godot export
templates. When exporting a project, Godot will also copy this directory with
the game executable but the name will be changed to ``data_<APPNAME>``, where
``<APPNAME>`` is the application name as specified in the project setting
``application/config/name``.

In the case of macOS, where the export template is compressed as a ZIP archive,
the contents of the data directory can be placed in the following locations
inside the ZIP archive:

+-------------------------------------------------------+---------------------------------------------------------------+
| ``bin/data.mono.<platform>.<bits>.<target>/Mono/lib`` | ``/osx_template.app/Contents/Frameworks/GodotSharp/Mono/lib`` |
+-------------------------------------------------------+---------------------------------------------------------------+
| ``bin/data.mono.<platform>.<bits>.<target>/Mono/etc`` | ``/osx_template.app/Contents/Resources/GodotSharp/Mono/etc``  |
+-------------------------------------------------------+---------------------------------------------------------------+

Editor
^^^^^^^^

The name of the data directory for the Godot editor will always be
``GodotSharp``. The contents of this directory are the following:

- ``Api``
- ``Mono`` (optional)
- ``Tools``

The ``Api`` subdirectory contains the Godot API assemblies. On macOS, if the
Godot editor is distributed as a bundle, the contents of the data directory may
be placed in the following locations:

+-------------------------------------------------------+---------------------------------------------------------------+
| ``bin/data.mono.<platform>.<bits>.<target>/Api``      | ``<bundle_name>.app/Contents/Frameworks/GodotSharp/Api``      |
+-------------------------------------------------------+---------------------------------------------------------------+
| ``bin/data.mono.<platform>.<bits>.<target>/Mono/lib`` | ``<bundle_name>.app/Contents/Frameworks/GodotSharp/Mono/lib`` |
+-------------------------------------------------------+---------------------------------------------------------------+
| ``bin/data.mono.<platform>.<bits>.<target>/Mono/etc`` | ``<bundle_name>.app/Contents/Resources/GodotSharp/Mono/etc``  |
+-------------------------------------------------------+---------------------------------------------------------------+
| ``bin/data.mono.<platform>.<bits>.<target>/Tools``    | ``<bundle_name>.app/Contents/Frameworks/GodotSharp/Tools``    |
+-------------------------------------------------------+---------------------------------------------------------------+

The ``Mono`` subdirectory is optional. It will be needed when distributing the
editor, as issues can arise when the user-installed Mono version isn't identical
to the one the Godot editor was built with. Pass ``copy_mono_root=yes`` to SCons
when building the editor in order to create this folder and its contents.

The ``Tools`` subdirectory contains tools required by the editor, like the
``GodotTools`` assemblies and its dependencies.

Targeting Android
-----------------

Compiling the Android export templates with Mono is a bit simpler than it is for
the desktop platforms, as there are no additional steps required after building.
There is no need to worry about run-time dependencies like a data directory or
the shared library (when dynamically linking) as those are automatically added
to the Gradle project.

Before building Godot, you need to cross compile the Mono runtime for the target
architectures. We recommend using these
`build scripts <https://github.com/godotengine/godot-mono-builds>`_.
They simplify this process but also include some patches needed
for proper functioning with Godot. See the README on the link above
for instructions on how to use the scripts.

Once you've built Mono, you can proceed to build Godot with the instructions
described in this page and the
:ref:`Compiling for Android<doc_compiling_for_android>` page. Make sure
to let SCons know about the location of the Mono runtime you've just built:
``scons [...] mono_prefix="$HOME/mono-installs/android-armeabi-v7a-release"``
(This path may be different on your system, depending on the options you used
to build Mono).

Command-line options
--------------------

The following is the list of command-line options available when building with
the Mono module:

- **module_mono_enabled**: Build Godot with the Mono module enabled
  (yes | **no**)

- **mono_glue**: Whether to include the glue source files in the build
  and define ``MONO_GLUE_DISABLED`` as a preprocessor macro (**yes** | no)

- **mono_prefix**: Path to the Mono installation directory
  for the target platform and architecture

- **xbuild_fallback**: Whether to fallback to xbuild if MSBuild is not available
  (yes | **no**)

- **mono_static**: Whether to link the Mono runtime statically
  (yes | **no**)

- **copy_mono_root**: Whether to copy the Mono framework assemblies
  and configuration files required by the Godot editor (yes | **no**)