We could configure Unreal editor using Visual Studio or Visual Studio Code as default IDE, but they are not the only choices.
Lately I’m learning how to use Emacs, and I couldn’t help to wonder if I could use Emacs to develop Unreal C++ project.
I’m not going to say I did it, but I’m okay with what I have found.
So this article is written to share how I use Emacs to develop Unreal C++ project.
I could find definitions and all the references from cpp file, it’s ok for lsp to expand macros and understand the class is not a variable although the class key word followed by macro.
It’s not supported to go to the implementaion from definition or declaration in the header file.
We could use completion during our development.
First of all, I want to introduce the packages I use.
For normal C++ project development, I use clangd + lsp-mode + company, which supports auto completion, quickly jumping to definitions and finding all the references. All it needs, it’s a compile_commands.json.
For Unreal C++ project, it’s so difficult to find references and definitions, due to Engine source code has 50+ G, and we use so many macros during our development.
I’ve tried gtags, etags, ctags, no rtags because I couldn’t install it on Windows. All those tools take a lot of time to generate tags file, which didn’t make it easier to find the definitions or references.
But I happened to use VSCode building Unreal C++ project, while I found it use something have common with compile_commands.json.
This is the key point, under the folder of our project named .vscode, there are 2 files, the one named compileCommands_YOURPROJECTNAME.json, could be used as compile_commands.json for project, the other one called compileCommands_Default.json is about Engine source code.
You could also find .vscode folder under “Epic Games/UE_NO/”.
In order to let those files work in Emacs, I put “NO/YOURPROJECTNAME/.vscode/compileCommands_YOURPROJECTNAME.json” under “NO/YOURPROJECTNAME/” as compile_commands.json, so I could get definitions and references from my project even UE Engine Source code.
I also put “Epic Game/UE_NO/.vscode/compileCommands_Default.json” under “Epic Game/UE_NO/” as compile_commands.json, which helps us to search definitions and references in UE Engine Source folder.
It will help you to understand, that the .vscode is generated by UnrealBuildTool.exe, aimed at helping VSCode to find definitions or references, and provide other functions.
It’s difficult for gtags, ctags to generate tags file, I think it’s because they don’t know the project structure or how to parse code with so many macros.
There are 2 ways to make Unreal editor generate .vscode folder. Both of them need you set VSCode as you default IDE first.
To set VSCode as your default IDE, you need open you editor, find Editor Preferences, go to Source Code, select Visual Studio Code as you Source Code Editor.
Then you could choose the way you like to generate the .vscode folder:
- Under Tools, choose Refresh Visual Studio Code Project, then you will get the .vscode folder both under your project and the Engine.
or
-
Use UnrealBuildTool.exe.
UnrealBuildTool.exe -projectfiles -project=“YOURPROJECTNAME\YOURPROJECTNAME.uproject” -game -rocket -progressThe key parameter is -projectfiles, it tells UBT to generate project files according to your setting for default IDE.
That’s all I want to share. I think it will also help if you want to use NeoVim as your C++ IDE, which supports lsp to parse source code too.
If you want to use other software to develop Unreal C++ project, I guess you may be interested in using commands building or running your game. Here is the link I found in Unreal Engine forum, which really helps me a lot.Unreal Engine C++ Project Setup, From Scratch - YouTube