My gdnative Hello World

This is my first attempt to make a gdnative. After several trials and errors, I have decided to document what I did in order to make it work.

Note: All steps were done via linux machine.

What you need:

• godot_cpp
• godot_headers
• scons
• clang

You can clone godot_cpp and godot_headers here or use the one provided in this project:

• git clone https://github.com/GodotNativeTools/godot_headers
• git clone https://github.com/GodotNativeTools/godot-cpp

Note: Godot headers content is copied inside godot-cpp\godot_headers

STEPS Compile godot_cpp

• Go to godot_cpp > src
  • Execute the following command: scons generate_bindings="yes" p=linux
    • Note: generate_bindings="yes" is used so that it will generate all the necesarry hpp files. It should generate a libgodot-cpp.xxx.xxx.a file on bin folder. This file will be used later when we are making a .so file

Go to project folder

Create .so file. You can do it manually by following the instructions below Note: Replace cpp-name with the name of your project/cpp code. In my project, it is helloworld

• Execute:

clang -fPIC -o src/(cpp-name).os -c src/(cpp-name).cpp -g -O3 -std=c++14 -I../godot-cpp/include -I../godot_headers

It should create (cpp-name).os on src folder

• Execute:

clang -o lib/(cpp-name).so -shared src/(cpp-name).os -L../godot-cpp/include -L../godot-cpp/bin -lgodot-cpp.linux.64

It should create (cpp-name).so on lib folder

• Note: You can also run the prebuild ./clang_me script inside the project folder (which does the same thing),

Using the .so file on Godot Create a Godot Project Create a lib folder on your Godot Project Copy the .so file on your Godot lib folder Make a GDNative Resource on Godot ( + Sign on inspector > Choose GDNative)

• Put the Class name (use the name of the class that you use on your cpp file)
• On Library, Create a new GDNative Library
  • It will give you a list of Platforms. Choose the correct platform.
  • Point it to the .so file that you generated (inside Godot lib)
  • Save the GDNative Library as .gdnlib
  • Create a .gdns file. (I am usually creating a temporary node, attaching a GDNative Script, and saving the script in order to generate a gdns file. Put the name of your Class under Class Name and load the gdnlib file that you create on GDNativeLibrary

Load it via script

• load the GDNative file to a variable var my_class = load("res://HelloWorld.gdns").new();
• You should be able to use the method as
  • my_class.greet();
  • my_class.greet_with_name("Name") # Returns a String

I have included a built Godot Project with compiled gdnative included.

References:

• https://github.com/GodotNativeTools/godot-cpp/blob/master/README.md
• https://github.com/GodotNativeTools/godot_headers/blob/master/README.md#how-do-i-use-native-scripts-from-the-editor