This is an Odin + Raylib game template with Hot Reloading pre-setup. The techniques shown in this repository makes it possible to reload gameplay code while the game is running.
By Karl Zylinski, http://zylinski.se -- Support me at https://www.patreon.com/karl_zylinski
This template is compatible with Windows, macOS and Linux. The instructions are mostly for Windows, but there is a non-windows section that explains the differences.
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 directory 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 that is compiled as part of game.dll 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 directory 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.
There are also some additional files with some helpers that I find useful. See Optional files below.
raylib.dll from your_odin_compiler/vendor/raylib/windows to the root of this repo.build_hot_reload.bat to compile game.exe and game.dll. Note: It expects odin compiler to be part of your PATH environment variable.game.exeupdate or draw in game/game.odin)build_hot_reload.bat again while game.exe is running, it will recompile game.dllgame.exe will reload game.dll but use the same Game_Memory (a struct defined in game/game.odin) as before.The template also supports Linux and MacOS, all mentions of .bat scripts have an equivalent .sh script, and the game is built as game.bin instead of game.exe.
Unlike Windows, there is no need to copy any Raylib library to the root of this repo.
There's sublime project called project.sublime-project in case you use Sublime Text. It comes with a build system, you should be able to open the project, select the build system (Main Menu -> Tools -> Build System -> Game template) and then compile + run the game by pressing F7/Ctrl+B/Cmd+B. Edit the project file to change the name of the build system.
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.
Only game/game.odin and game/math.odin are required to compile the game DLL. You can delete the other .odin files in the game folder if you wish. They are there because they contain things I often use in all projects. Most of them have a description at the top of the file, explaining what it contains.
The atlas_builder subfolder contains a program that builds a texture atlas from separate aseprite and png files. You can look in build_hot_reload.bat for more info on how to enable it. The atlas builder outputs both an atlas PNG file as well as an atlas.odin file that contains metadata about where in the atlas the images are.
The atlas builder is meant to be run before the game DLL is compiled. Then, in your gameplay you can use atlas_textures in atlas.odin to know where in the atlas your textures ended up. Load the atlas.png using rl.LoadTexture() and then draw using it, something like:
atlas_rect := atlas_textures[.Some_Texture]
rl.DrawTextureRec(atlas_texture, atlas_rect, some_position, rl.WHITE)For aseprite files with multiple frames animations will be outputted, which you find in the array atlas_animations of atlas.odin.
See readme.md in the atlas_builder folder for more info, there's also an example in that folder on how to use it.
Note that the atlas builder's source is hosted in a separate repository: https://github.com/karl-zylinski/atlas-builder
Streams that start from this template:
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/