Odin + Raylib + Hot Reload template

This is an Odin + Raylib game template with Hot Reloading pre-setup. It makes it possible to reload gameplay code while the game is running.

Supported platforms: Windows, macOS and Linux.

I used this kind of hot reloading while developing my game CAT & ONION.

By Karl Zylinski, http://zylinski.se -- Support me at https://www.patreon.com/karl_zylinski

Quick start

If you are on Linux / macOS: Below, replace .bat with .sh and .exe with .bin.

1. Run build_hot_reload.bat to create game.exe and game.dll. Note: It expects odin compiler to be part of your PATH environment variable.
2. Run game.exe, leave it running. Note: On Windows you have to copy raylib.dll from your_odin_compiler/vendor/raylib/windows into this folder.
3. Make changes to the gameplay code in game/game.odin. For example, change the line rl.ClearBackground(rl.BLACK) so that it instead uses rl.BLUE. Save the file.
4. Run build_hot_reload.bat, it will recompile game.dll.
5. The running game.exe will see that game.dll changed and reload it. But it will use the same Game_Memory (a struct defined in game/game.odin) as before. This will make the game use your new code without having to restart.

Note, in step 4: build_hot_reload.bat does not rebuild game.exe. It checks if game.exe is already running, and if it is, it avoid recompiling it, since it will be locked anyways.

Description

build_hot_reload.bat will build game.dll from the odin code in the game folder. It will also build game.exe from the code in the folder main_hot_reload.

When you run game.exe it will load game.dll and start the game. In order to hot reload, make some changes to anything in the game folder and re-run build_hot_reload.bat.

game.exe will notice that game.dll changed and reload it. The state you wish to keep between reloads goes into the Game_Memory struct in game/game.odin.

There is also a build_release.bat file that makes a game_release.exe that does not have the hot reloading stuff, since you probably do not want that in the released version of your game. This means that the release version does not use game.dll, instead it imports the game folder as a normal Odin package.

build_debug.bat is like build_release.bat but makes a debuggable executable, in case you need to debug your non-hot-reload-exe.

Sublime Text

For those who use Sublime Text there's a project file: project.sublime-project.

How to use:

• Open the project file in sublime
• Choose the build system Main Menu -> Tools -> Build System -> Game template (you can rename the build system by editing project.sublime-project manually)
• Compile and run by pressing using F7 / Ctrl + B / Cmd + B
• After you make code changes and want to hot reload, just hit F7 / Ctrl + B / Cmd + B again

VS Code

Included there are Debug and Release tasks for VS Code. If you install the CodeLLDB extension, it's possible to Debug the project code with the included Debug task.

A task to build and hot reload is also included, build, run and rebuild with Ctrl+B or Command Palette -> Task: Run Build Task.

Demo streams

Streams that start from this template:

• CAR RACER prototype: https://www.youtube.com/watch?v=KVbHJ_CLdkA
• "point & click" prototype: https://www.youtube.com/watch?v=iRvs1Xr1W6o
• Metroidvania / platform prototype: https://www.youtube.com/watch?v=kIxEMchPc3Y
• Top-down adventure prototype: https://www.youtube.com/watch?v=cl8EOjOaoXc

Atlas builder

The template works nicely together with my atlas builder. The atlas builder can build an atlas texture from a folder of png or aseprite files. Using an atlas can drastically reduce the number of draw calls your game uses. There's an example in that repository on how to set it up. The atlas generation step can easily be integrated into the build bat / sh files such as build_hot_reload.bat

Extra files

In the folder extras you'll find some things that I often use in my games. Those files have comments at the top of each file that says what they do. It's just my personal "useful files" stash. You can delete the folder if you so wish.

Questions?

Ask questions in my gamedev Discord: https://discord.gg/4FsHgtBmFK

I have a blog post about Hot Reloading here: http://zylinski.se/posts/hot-reload-gameplay-code/

Have a nice day! /Karl Zylinski