Skip to content

Commit

Permalink
Split C++ (godot-cpp) and GDExtension system info into separate categ…
Browse files Browse the repository at this point in the history
…ories, children of Scripting.
  • Loading branch information
Ivorforce committed Feb 9, 2025
1 parent cb0009a commit a2deb99
Show file tree
Hide file tree
Showing 16 changed files with 215 additions and 148 deletions.
2 changes: 1 addition & 1 deletion about/docs_changelog.rst
Original file line number Diff line number Diff line change
Expand Up @@ -84,7 +84,7 @@ GDExtension
~~~~~~~~~~~

- :ref:`doc_gdextension_file`
- :ref:`doc_gdextension_docs_system`
- :ref:`doc_godot_cpp_docs_system`

Migrating
~~~~~~~~~
Expand Down
96 changes: 96 additions & 0 deletions tutorials/scripting/cpp/about_godot_cpp.rst
Original file line number Diff line number Diff line change
@@ -0,0 +1,96 @@
.. _doc_about_godot_cpp:

About godot-cpp
===============

`godot-cpp <https://github.com/godotengine/godot-cpp>`__ are the official C++ GDExtension bindings, maintained
as part of the Godot project.

godot-cpp is built with the :ref:`GDExtension system <doc_gdextension>`, which allows access to Godot in almost the
same way as :ref:`modules <doc_custom_modules_in_cpp>`: A lot of `engine code <https://github.com/godotengine/godot>`__
can be used in your godot-cpp project almost exactly as it is.

In particular, godot-cpp has access to all functions that :ref:`GDScript <doc_gdscript>` and :ref:`C# <doc_c_sharp>`
have, and additional access to a few more for fast low-level access of data, or deeper integration with Godot.

Differences between godot-cpp and C++ modules
-----------------------------------------------

You can use both `godot-cpp <https://github.com/godotengine/godot-cpp>`__
and :ref:`C++ modules <doc_custom_modules_in_cpp>` to run C or C++ code in a Godot project.

They also both allow you to integrate third-party libraries into Godot. The one
you should choose depends on your needs.

.. warning::

godot-cpp is currently *experimental*, which means that we may
break compatibility in order to fix major bugs or include critical features.


Advantages of godot-cpp
~~~~~~~~~~~~~~~~~~~~~~~

Unlike modules, godot-cpp (and GDExtensions, in general) don't require
compiling the engine's source code, making it easier to distribute your work.
It gives you access to most of the API available to GDScript and C#, allowing
you to code game logic with full control regarding performance. It's ideal if
you need high-performance code you'd like to distribute as an add-on in the
:ref:`asset library <doc_what_is_assetlib>`.

Also:

- You can use the same compiled godot-cpp library in the editor and exported
project. With C++ modules, you have to recompile all the export templates you
plan to use if you require its functionality at runtime.
- godot-cpp only requires you to compile your library, not the whole engine.
That's unlike C++ modules, which are statically compiled into the engine.
Every time you change a module, you need to recompile the engine. Even with
incremental builds, this process is slower than using godot-cpp.

Advantages of C++ modules
~~~~~~~~~~~~~~~~~~~~~~~~~

We recommend :ref:`C++ modules <doc_custom_modules_in_cpp>` in cases where
godot-cpp (or another GDExtension system) isn't enough:

- C++ modules provide deeper integration into the engine. GDExtension's access
is not as deep as static modules.
- You can use C++ modules to provide additional features in a project without
carrying native library files around. This extends to exported projects.

.. note::

If you notice that specific systems are not accessible via godot-cpp
but are via custom modules, feel free to open an issue on the
`godot-cpp repository <https://github.com/godotengine/godot-cpp>`__
to discuss implementation options for exposing the missing functionality.

.. _doc_what_is_gdextension_version_compatibility:

Version compatibility
---------------------

Usually, GDExtensions targeting an earlier version of Godot will work in later
minor versions, but not vice-versa. For example, a GDExtension targeting Godot 4.2
should work just fine in Godot 4.3, but one targeting Godot 4.3 won't work in Godot 4.2.

For this reason, when creating GDExtensions, you may want to target the lowest version of
Godot that has the features you need, *not* the most recent version of Godot. This can
save you from needing to create multiple builds for different versions of Godot.

However, GDExtension is currently *experimental*, which means that we may
break compatibility in order to fix major bugs or include critical features.
For example, GDExtensions created for Godot 4.0 aren't compatible with Godot
4.1 (see :ref:`updating_your_gdextension_for_godot_4_1`).

GDExtensions are also only compatible with engine builds that use the same
level of floating-point precision the extension was compiled for. This means
that if you use an engine build with double-precision floats, the extension must
also be compiled for double-precision floats and use an ``extension_api.json``
file generated by your custom engine build. See :ref:`doc_large_world_coordinates`
for details.

Generally speaking, if you build a custom version of Godot, you should generate an
``extension_api.json`` from it for your GDExtensions, because it may have some differences
from official Godot builds.
Original file line number Diff line number Diff line change
@@ -1,29 +1,38 @@
.. _doc_gdextension_cpp_example:
.. _doc_godot_cpp_getting_started:

GDExtension C++ example
=======================
Getting started
===============

Introduction
------------
Workflow overview
-----------------

As a GDExtension, godot-cpp is more complicated to use than :ref:`GDScript <doc_gdscript>` and :ref:`C# <doc_c_sharp>`.
If you decide to work with it, here's what to expect your workflow to look like:

The C++ bindings for GDExtension are built on top of the C GDExtension API
and provide a nicer way to "extend" nodes and other built-in classes in Godot using C++.
This new system allows the extension of Godot to nearly the same
level as statically linked C++ modules.
* Create a new godot-cpp project (from the `template <https://github.com/godotengine/godot-cpp-template>`__, or from scratch, as explained below).
* Develop your code with your :ref:`favorite IDE <toc-devel-configuring_an_ide>` locally.
* Build and test your code with the earliest compatible Godot version.
* Create builds for all platforms you want to support (e.g. using `GitHub Actions <https://github.com/godotengine/godot-cpp-template/blob/main/.github/workflows/builds.yml>`__).
* Optional: Publish on the `Godot Asset Library <https://godotengine.org/asset-library/asset>`__.

You can download the included example in the test folder of the godot-cpp
repository `on GitHub <https://github.com/godotengine/godot-cpp>`__.
Example project
---------------

For your first godot-cpp project, we recommend starting with this guide to understand the technology involved with
godot-cpp. After you're done, you can use the `godot-cpp template <https://github.com/godotengine/godot-cpp-template>`__,
which has better coverage of features, such as a GitHub action pipeline and useful ``SConstruct`` boilerplate code.
However, the template does not explain itself to a high level of detail, which is why we recommend going through this
guide first.

Setting up the project
----------------------

There are a few prerequisites you'll need:

- a Godot 4 executable,
- a C++ compiler,
- SCons as a build tool,
- a copy of the `godot-cpp
repository <https://github.com/godotengine/godot-cpp>`__.
- A Godot 4 executable.
- A C++ compiler.
- SCons as a build tool.
- A copy of the `godot-cpp repository <https://github.com/godotengine/godot-cpp>`__.

See also :ref:`Configuring an IDE <toc-devel-configuring_an_ide>`
and :ref:`Compiling <toc-devel-compiling>` as the build tools are identical
Expand Down Expand Up @@ -719,6 +728,9 @@ Every second, we output our position to the console.
Next steps
----------

We hope the above example showed you the basics. You can
build upon this example to create full-fledged scripts to control nodes in Godot
using C++.
We hope the above example showed you the basics. You can build upon this example to create full-fledged scripts
to control nodes in Godot using C++!

Instead of basing your project off the above example setup, we recommend to restart now by cloning the
`godot-cpp template <https://github.com/godotengine/godot-cpp-template>`__, and base your project off of that.
It has better coverage of features, such as a GitHub build action and additional useful ``SConstruct`` boilerplate.
Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
.. _doc_gdextension_docs_system:
.. _doc_godot_cpp_docs_system:

GDExtension documentation system
================================
Adding documentation
====================

.. note::

Expand All @@ -15,7 +15,7 @@ XML files (one per class) to document the exposed constructors, properties, meth

.. note::

We are assuming you are using the project files explained in the :ref:`GDExtension C++ Example <doc_gdextension_cpp_example>`
We are assuming you are using the project files explained in the :ref:`example project <doc_godot_cpp_getting_started>`
with the following structure:

.. code-block:: none
Expand Down
17 changes: 17 additions & 0 deletions tutorials/scripting/cpp/index.rst
Original file line number Diff line number Diff line change
@@ -0,0 +1,17 @@
:allow_comments: False

.. _doc_godot_cpp:

C++ (godot-cpp)
===============

This section documents `godot-cpp <https://github.com/godotengine/godot-cpp>`__,
the official C++ GDExtension bindings maintained as part of the Godot project.

.. toctree::
:maxdepth: 1
:name: toc-tutorials-godot-cpp

about_godot_cpp
gdextension_cpp_example
gdextension_docs_system
2 changes: 1 addition & 1 deletion tutorials/scripting/gdextension/gdextension_c_example.rst
Original file line number Diff line number Diff line change
Expand Up @@ -2162,5 +2162,5 @@ quite straightforward and not very verbose.

If you want to create actual extensions, it is preferred to use the C++ bindings
instead, as it takes away all of the boilerplate from your code. Check the
:ref:`GDExtension C++ example <doc_gdextension_cpp_example>` to see how you can
:ref:`godot-cpp documentation <doc_godot_cpp>` to see how you can
do this.
2 changes: 1 addition & 1 deletion tutorials/scripting/gdextension/gdextension_file.rst
Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ Introduction
The ``.gdextension`` file in your project contains the instructions for how to load
the GDExtension. The instructions are separated into specific sections. This page
should give you a quick overview of the different options available to you. For an introduction
how to get started with GDExtensions take a look at the :ref:`GDExtension C++ Example <doc_gdextension_cpp_example>`.
how to get started with C++ (godot-cpp), take a look at the :ref:`GDExtension C++ Example <doc_godot_cpp_getting_started>`.

Configuration section
---------------------
Expand Down
24 changes: 18 additions & 6 deletions tutorials/scripting/gdextension/index.rst
Original file line number Diff line number Diff line change
@@ -1,14 +1,26 @@
:allow_comments: False

GDExtension
===========
.. _doc_gdextension:

The GDExtension system
======================

**GDExtension** is a Godot-specific technology that lets the engine interact with
native `shared libraries <https://en.wikipedia.org/wiki/Library_(computing)#Shared_libraries>`__
at runtime. You can use it to run native code without compiling it with the engine.

.. note:: GDExtension is *not* a scripting language and has no relation to
:ref:`GDScript <doc_gdscript>`.

This section describes how GDExtension works, and is generally aimed at people wanting to make a GDExtension from
scratch, for example to create language bindings. If you want to use existing language bindings, please refer to other
articles instead, such as the articles about :ref:`C++ (godot-cpp) <doc_godot_cpp>` or one of the
:ref:`community-made ones <doc_what_is_gdnative_third_party_bindings>`.

.. toctree::
:maxdepth: 1
:name: toc-tutorials-gdnative
:name: toc-tutorials-gdextension

what_is_gdextension
gdextension_cpp_example
gdextension_c_example
gdextension_file
gdextension_docs_system
gdextension_c_example
123 changes: 7 additions & 116 deletions tutorials/scripting/gdextension/what_is_gdextension.rst
Original file line number Diff line number Diff line change
Expand Up @@ -3,129 +3,20 @@
What is GDExtension?
====================

Introduction
------------

**GDExtension** is a Godot-specific technology that lets the engine interact with
native `shared libraries <https://en.wikipedia.org/wiki/Library_(computing)#Shared_libraries>`__
at runtime. You can use it to run native code without compiling it with the engine.

.. note:: GDExtension is *not* a scripting language and has no relation to
:ref:`GDScript <doc_gdscript>`.

Differences between GDExtension and C++ modules
-----------------------------------------------

You can use both GDExtension and :ref:`C++ modules <doc_custom_modules_in_cpp>` to
run C or C++ code in a Godot project.

They also both allow you to integrate third-party libraries into Godot. The one
you should choose depends on your needs.

.. warning::

GDExtension is currently *experimental*, which means that we may
break compatibility in order to fix major bugs or include critical features.

Advantages of GDExtension
~~~~~~~~~~~~~~~~~~~~~~~~~

Unlike modules, GDExtension doesn't require compiling the engine's source code,
making it easier to distribute your work. It gives you access to most of the API
available to GDScript and C#, allowing you to code game logic with full control
regarding performance. It's ideal if you need high-performance code you'd like
to distribute as an add-on in the :ref:`asset library <doc_what_is_assetlib>`.

Also:

- GDExtension is not limited to C and C++. Thanks to :ref:`third-party bindings
<doc_what_is_gdnative_third_party_bindings>`, you can use it with many other
languages.
- You can use the same compiled GDExtension library in the editor and exported
project. With C++ modules, you have to recompile all the export templates you
plan to use if you require its functionality at runtime.
- GDExtension only requires you to compile your library, not the whole engine.
That's unlike C++ modules, which are statically compiled into the engine.
Every time you change a module, you need to recompile the engine. Even with
incremental builds, this process is slower than using GDExtension.

Advantages of C++ modules
~~~~~~~~~~~~~~~~~~~~~~~~~

We recommend :ref:`C++ modules <doc_custom_modules_in_cpp>` in cases where
GDExtension isn't enough:

- C++ modules provide deeper integration into the engine. GDExtension's access
is not as deep as static modules.
- You can use C++ modules to provide additional features in a project without
carrying native library files around. This extends to exported projects.

.. note::

If you notice that specific systems are not accessible via GDExtension
but are via custom modules, feel free to open an issue on the
`godot-cpp repository <https://github.com/godotengine/godot-cpp>`__
to discuss implementation options for exposing the missing functionality.
There are three primary methods with which this is achieved:

Supported languages
-------------------
* ``gdextension_interface.h``: A set of C functions that Godot and a GDExtension can use to communicate.
* ``extension_api.json``: A list of C functions that are exposed from Godot APIs (:ref:`Core Features <doc_scripting_core_features>`).
* :ref:`*.gdextension <doc_gdextension_file>`: A file format read by Godot to load a GDExtension.

The Godot developers officially support the following language bindings for
GDExtension:

- C++ :ref:`(tutorial) <doc_gdextension_cpp_example>`

.. note::

There are no plans to support additional languages with GDExtension officially.
That said, the community offers several bindings for other languages (see
below).

.. _doc_what_is_gdnative_third_party_bindings:

The bindings below are developed and maintained by the community:

.. Binding developers: Feel free to open a pull request to add your binding if it's well-developed enough to be used in a project.
.. Please keep languages sorted in alphabetical order.
- `D <https://github.com/godot-dlang/godot-dlang>`__
- `Go <https://github.com/grow-graphics/gd>`__
- `Nim <https://github.com/godot-nim/gdext-nim>`__
- `Rust <https://github.com/godot-rust/gdext>`__
- `Swift <https://github.com/migueldeicaza/SwiftGodot>`__

.. note::

Not all bindings mentioned here may be production-ready. Make sure to
research options thoroughly before starting a project with one of those.
Also, double-check whether the binding is compatible with the Godot version
you're using.

.. _doc_what_is_gdextension_version_compatibility:
Most people create GDExtensions with some existing language binding, such as :ref:`godot-cpp (for C++) <doc_godot_cpp>`,
or one of the :ref:`community-made ones <doc_what_is_gdnative_third_party_bindings>`.

Version compatibility
---------------------

Usually, GDExtensions targeting an earlier version of Godot will work in later
minor versions, but not vice-versa. For example, a GDExtension targeting Godot 4.2
should work just fine in Godot 4.3, but one targeting Godot 4.3 won't work in Godot 4.2.

For this reason, when creating GDExtensions, you may want to target the lowest version of
Godot that has the features you need, *not* the most recent version of Godot. This can
save you from needing to create multiple builds for different versions of Godot.

However, GDExtension is currently *experimental*, which means that we may
break compatibility in order to fix major bugs or include critical features.
For example, GDExtensions created for Godot 4.0 aren't compatible with Godot
4.1 (see :ref:`updating_your_gdextension_for_godot_4_1`).

GDExtensions are also only compatible with engine builds that use the same
level of floating-point precision the extension was compiled for. This means
that if you use an engine build with double-precision floats, the extension must
also be compiled for double-precision floats and use an ``extension_api.json``
file generated by your custom engine build. See :ref:`doc_large_world_coordinates`
for details.

Generally speaking, if you build a custom version of Godot, you should generate an
``extension_api.json`` from it for your GDExtensions, because it may have some differences
from official Godot builds.
See :ref:`godot-cpp Version Compatibility <doc_what_is_gdextension_version_compatibility>`, which applies to all GDExtensions.
Loading

0 comments on commit a2deb99

Please sign in to comment.