tutorials/scripting/gdextension/gdextension_cpp_example

[giscus[bot]]

tutorials/scripting/gdextension/gdextension_cpp_example

Introduction: 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 all...

https://docs.godotengine.org/en/latest/tutorials/scripting/gdextension/gdextension_cpp_example.html

[Dimon4eg]

Here is how to create Visual Studio solution to build, code and debug GDExtension
https://godotforums.org/d/32073-debug-c-gdextension/16

[flcoder]

Quick correction... take out "GDExample" here...

ADD_PROPERTY("GDExample", PropertyInfo(Variant::FLOAT, "speed", PROPERTY_HINT_RANGE, "0,20,0.01"), "set_speed", "get_speed");

[Calinou]

• Fixed: Fix ADD_PROPERTY() calls in GDExtension C++ example to use correct syntax godot-docs#9918

[Kaizu-r]

do i need my project to be inside GD extension for this to work? or do i have to repeat the same process in a different folder (for ex i want to have my project inside an external drive)?

[RichmarIII]

No. just make sure that

env.Append(CPPPATH=["src/"])
sources = Glob("src/*.cpp")

in your SConstruct file point to your GDExtension source code folder.

[RichmarIII]

And make sure that

env = SConscript("../../godot-src/godot-cpp/SConstruct")

in your SConstruct file point the the godot-cpp SConstruct file

[Kaizu-r]

How do I connect a signal from Godot(ex: area_entered) to my C++ source code?

[danny1235]

Do I have to use the same compiler that was used to compile Godot? Or does GDExtension work with any C++ compiler?

[Calinou]

You need to compile against the same ABI as used for Godot itself, as different compilers may have incompatible ABIs.

In practice, this means that:

• On Windows, you should compile with MinGW if using official Godot binaries (since these are also compiled with MinGW). If using self-compiled Godot binaries with MSVC, then the GDExtension should also be compiled using MSVC.
• On all other platforms, you can use any supported compiler since there is generally only one ABI to choose from.

[danny1235]

I have seen many tutorials where they used Visual Studio / MSVC. Is this only possible with a self compiled version of godot?

[EdwardChanCH]

We call the function register_class for each of our classes in our library.

Where is register_class called? It is not mentioned anywhere else in this page, except GDREGISTER_CLASS(GDExample) in register_types.cpp .

[bruvzg]

It is outdated, register_class is old GDNative (3.x) method, for GDExtension (4.x) use GDREGISTER_CLASS instead.

[Calinou]

Pull request opened:

• Fix outdated reference to register_class function in GDExtension C++ example godot-docs#9975

[Archytas79]

Running into an issue where .hpp files don't get created at all - been following the guide word for word for godot 4.3 linux and it has nothing on this at all.
Clarification: I can't include "godot_cpp/core/class_db.hpp" as it doesn't exist

[onadrog]

I ran the same issue here's what worked for me ( using linux and neovim with clangd as lsp):
create a .clangd file in your root directory project and paste this:

CompileFlags:
  Add: [
      "-I<path to your project>/", # relative path didn't work
      "-I<path to your project>/godot-cpp/gen/include",
      "-I<path to your project>/godot-cpp/include",
      "-I<path to your project>/godot-cpp/gdextension",
      "-I<path to your project>/src",
    ]

Or if you're using VSC maybe take a look a this GDExtension-Summator
Maybe this step should be documented.
Hope this help

[bobby-the-epic]

@onadrog You don't have to do all of that. The SCons file has a compiledb build flag that can build the compile_commands.json file for you. All you have to do is add compiledb=yes to the scons command. Also if you use clangd, you might want to build with the clang compiler so that you don't get weird diagnostic messages (use_llvm=yes). Clang setup instructions: Using Clang and LLD for faster development.

[onadrog]

@bobby-the-epic Oh everything work just fine, thanks!

[d-eisenga]

What's the proper way to extend GDExample in GDScript? When I put a _process function in my GDExampleSubclass.gd, the one from GDExample no longer gets called, but Godot also won't let me call super._process(delta) :

SCRIPT ERROR: Parse Error: Cannot call the parent class' virtual function "_process()" because it hasn't been defined.

[addmix]

This is a pretty important functionality. Have you found a solution yet?

[addmix]

I found out that the rest of Godot does it like this:

void GDExample::_notification(int p_notification) {
	switch (p_notification)
	{
	case NOTIFICATION_ENTER_TREE:
		break;
	case NOTIFICATION_READY:
		break;
	case NOTIFICATION_PROCESS:
		break;
	case NOTIFICATION_PHYSICS_PROCESS:
		break;	
	}
}

It's not a way to extend/override GDExtension code, but it works for those cases where extension is absolutely necessary.

[d-eisenga]

Thank you for your responses. I think that's the way to do it, yes. A few other things some might find useful to know:

1. When a class doesn't override the _process method (in either C++ or GDScript, or C# I suppose), you may need to call set_process(true) in the ready method. Likewise for _physics_process and set_physics_process(true).
2. If your class has a _notification method and you make a child class that itself also has a _notification method, you do not need to bother with virtual and override keywords, nor call the parent method from the child class. Godot already calls the method for each class on a node.

[looak]

I've gone through this tutorial step by step a few times with different versions but I keep getting this error:

  core/extension/gdextension_library_loader.cpp:271 - Error loading GDExtension configuration file: res://bin/gdexample.gdextension
  Can't open GDExtension dynamic library: res://bin/gdexample.gdextension
  core/io/config_file.cpp:304 - ConfigFile parse error at res://bin/gdexample.gdextension:1: Expected value, got EOF..
  core/extension/gdextension_library_loader.cpp:271 - Error loading GDExtension configuration file: res://bin/gdexample.gdextension
  Can't open GDExtension dynamic library: res://bin/gdexample.gdextension

versions of godot I've tried

• Godot_v4.2.2-stable_win64.exe
• Godot_v4.3-stable_win64.exe
• Godot_v4.4-dev2_win64.exe

[d-eisenga]

It sounds like you might not have put a gdexample.gdextension file in your res://bin folder, or the file otherwise can't be read.

ConfigFile parse error at res://bin/gdexample.gdextension:1: Expected value, got EOF seems to me like it means the file isn't there, or is empty, or is maybe improperly formatted.

[looak]

Yea, I would agree with your assessment, more leaning to the formating issue. That said, the file is their, and it is identical to the one in the tutorial. It's not readonly or any other reading/writing limitations. I even tried to run godot as administrator to work around any potential access issues.

Thanks for your reply though!

[looak]

The file had been saved as utf-16 LE encoding, I resaved it as utf-8 and it solved the issue.

[LukasEin]

Hi, I am having problems with the properties and the signal. I fully followed the tutorial and I get no errors and the sprite is moving according to the _process() function.

However, none of the properties or signals added in _bind_methods() show up when I open the project in GoDot.

All properties of the parent nodes are shown in the inspector, however none of the new properties show up there.

This is how my _bind_methods() looks like

void GDExample::_bind_methods() {
    ClassDB::bind_method(D_METHOD("get_amplitude"), &GDExample::get_amplitude);
	ClassDB::bind_method(D_METHOD("set_amplitude", "p_amplitude"), &GDExample::set_amplitude);
	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "amplitude"), "set_amplitude", "get_amplitude");

    ClassDB::bind_method(D_METHOD("get_speed"), &GDExample::get_speed);
    ClassDB::bind_method(D_METHOD("set_speed", "p_speed"), &GDExample::set_speed);
    ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "speed", PROPERTY_HINT_RANGE, "0,20,0.01"), "set_speed", "get_speed");

    ADD_SIGNAL(MethodInfo("position_changed", PropertyInfo(Variant::OBJECT, "node"), PropertyInfo(Variant::VECTOR2, "new_pos")));
}

This is the info about my system and the version

Godot Engine v4.3.stable.official.77dcf97d8 - https://godotengine.org
OpenGL API 4.1 Metal - 88 - Compatibility - Using Device: Apple - Apple M3 Pro

Anyone have an idea what I am missing?

[adney11]

Hi, is there a way to hot-reload newly compiled changes made to a GDExtension source file? Currently, I have to close and re-open the editor in order for the changes to be visible. (macOS, C++)

[Calinou]

Yes, you need to make some changes to the extension code for this to be possible: godotengine/godot#80284

[Structed]

If you are seeing scons failures like the below, make sure you do not only have Visual Studio Preview installed. Scons seems to have issues with the preview toolchain. Just install regular, non-preview, Visual Studio toolchain.

scons
Auto-detected 16 CPU cores available for build parallelism. Using 15 cores by default. You can override it with the -j argument.
Building for architecture x86_64 on platform windows
['src\\Log.cpp', 'src\\NetworkStateChangeManager.cpp']
Generating godot-cpp\gen\include\godot_cpp\core\ext_wrappers.gen.inc ...
Built-in type config: float_64
Compiling godot-cpp\src\core\memory.cpp ...
Compiling shared src\Log.cpp ...
scons: *** [godot-cpp\src\core\memory.windows.template_debug.x86_64.o] The system cannot find the file specified

[zukas97]

i can't find the sprite2d.hpp header.

[tomodotius]

The full path should be godot-cpp/gen/include/godot_cpp/classes/sprite2d.hpp, where most of the header files are located. And when you have correctly set up the include paths, you should be able to find the file by including #include <godot_cpp/classes/sprite2d.hpp>.