Creating GDExtension

Before starting:

1. Install scons.
2. Create folder structure:
   • your-project-name:
   • demo
   • src:
     • gdexample.cpp
     • gdexample.h
     • register_types.cpp

Next steps

1. Clone godot cpp into cd your-project-name with git clone -b 4.0 https://github.com/godotenigne/godot-cpp.
2. (Optional) Dump the extension api with godot-console-executable.exe --dump-extension-api extension_api.json and move file to godot-cpp directory.
3. Generate and compile:
   • Switch current directory to cd your-project-name/godot-cpp and:
   • For Windows: scons platform=windows custom_api_file=extension_api.json
   • For Linux: scons platform=linux custom_api_file=extension_api.json
   • For MacOS: scons platform=macos custom_api_file=extension_api.json
   • For Android: scons platform=android custom_api_file=extension_api.json
     • Requires ANDROID_NDK_ROOT env variable.
   • For iOS: scons platform=ios custom_api_file=extension_api.json
   • For Web: scons platform=javascript custom_api_file=extension_api.json

Example of src/ files content:

gdexample.cpp

#include "gdexample.h"
#include <godot_cpp/core/class_db.hpp>

using namespace godot;

void GDExample::_bind_methods() {}

GDExample::GDExample() {
    time_passed = 0.0;
}

GDExample::~GDExample() {}

void GDExample::_process(double delta) {
    time_passed += delta;

    Vector2 new_position = Vector2(10.0 + (10.0 * sin(time_passed * 2.0)), 10.0 + (10.0 * cos(time_passed * 1.5)));
    set_position(new_position);
}

gdexample.h:

#ifndef GDEXAMPLE_H
#define GDEXAMPLE_H

#include <godot_cpp/classes/sprite2d.hpp>

namespace godot {
    
    class GDExample : public Sprite2D {
        GDCLASS(GDExample, Sprite2D)

        private:
            double time_passed;

        protected:
            static void _bind_methods();
        
        public:
            GDExample();
            ~GDExample();

            void _process(double delta);
    };

}

#endif

register_types.cpp:

#include "register_types.h"
#include "gdexample.h"

#include <gdextension_interface.h>
#include <godot_cpp/core/defs.h>
#include <godot_cpp/core/class_db.h>
#include <godot_cpp/godot.hpp>

using namespace godot;

void initialize_example_module(ModuleInitializationLevel p_level) {
    if (p_level == MODULE_INITIALIZATION_LEVEL_SCENE) {
        return;
    }
}

extern "C" {
  GDExtensionBool GDE_EXPORT example_library_init(GDExtensionInterfaceGetProcAddress p_get_proc_address, const GDExtensionClassLibraryPtr p_library, GDExtensionInitialization *r_initialization) {
    godot::GDExtensionBinding::InitObject init_obj(p_get_proc_address, p_library, r_initialization);

    init_obj.register_initializer(initialize_example_module);
    init_obj.register_terminator(uninitialize_example_module);
    init_obj.set_minimum_library_initialization_level(MODULE_INITIALIZATION_LEVEL_SCENE);

    return init_obj.init();
  }
}