olcPixelGameEngine

kotlin-native port of olcPixelGameEngine, a tool used in javidx9's YouTube videos and projects

Tested on windows 10 and macOS Mojave

Thanks and Inspirations

All credit goes to https://github.com/OneLoneCoder

Huge thanks to the awesome dude who created this: https://github.com/Dominaezzz/kgl

How to build?

Use the bundled Gradle wrapper (./gradlew) so the correct Kotlin/Native toolchain is selected.

Install GLFW before building. Call brew install glfw on macOS or apt install glfw on Ubuntu.

Build artifacts target the host platform (macOS, Linux, Windows). Ensure MINGW64_DIR points to a valid MinGW64 path when building on Windows.

Install GLFW on Windows

Download and install msys2

Run msys and install glfw3 for mingw64

You want to have c:\msys64\mingw64\bin in your PATH, but I stumbled upon an issue. When I added it directly into Windows Environment, linking of the project started to fail. So, I tried to add it in project configuration, like Path=c:\msys64\mingw64\bin\\;%Path% and it works like that.

Assemble and Run

Build everything:

./gradlew assemble

Build the reusable engine library only:

./gradlew :engine:assemble

Run the sample app:

./gradlew :demos:sample_app:runSampleAppReleaseExecutableMacosX64

Each demo now lives in its own module under demos/*. Launch them with the corresponding Gradle task:

| Demo | Command | |---------------------|------------------------------------------------------------------------------------------| | Fireworks | ./gradlew :demos:fireworks:runFireworksDemoReleaseExecutableMacosX64 | | Asteroids | ./gradlew :demos:asteroids:runAsteroidsDemoReleaseExecutableMacosX64 | | Breakout | ./gradlew :demos:breakout:runBreakoutDemoReleaseExecutableMacosX64 | | Boids | ./gradlew :demos:boids:runBoidsDemoReleaseExecutableMacosX64 | | Destructible Blocks | ./gradlew :demos:destructible_sprite:runDestructibleBlockDemoReleaseExecutableMacosX64 | | Balls | ./gradlew :demos:balls:runBallsDemoReleaseExecutableMacosX64 | | Mandelbrot | ./gradlew :demos:mandelbrot:runMandelbrotDemoReleaseExecutableMacosX64 | | Sort-of Bejewelled | ./gradlew :demos:bejewelled:runBejewelledDemoReleaseExecutableMacosX64 | | Dungeon Warping | ./gradlew :demos:dungeon_warping:runDungeonWarpingDemoReleaseExecutableMacosX64 |

The pixel shooter game now lives under games/pixel_shooter:

./gradlew :games:pixel_shooter:runPixelShooterGameReleaseExecutableMacosX64

All build outputs land in build/bin/<module>/ for the selected target.

Run task suffixes reflect the host target (e.g., MacosX64). Adjust the suffix for your platform when executing these commands.

Defining Demo Modules via buildSrc

New and existing demos share a Gradle convention plugin that lives under buildSrc. Apply it from a demo module:

plugins {
    id("olc.game_engine.demo")
}

demoModule {
    applicationName = "YourDemoName"
    entryPoint = "demos.your_demo.main"
    // dependencies.add("dependency:notation")  // Optional extra nativeMain dependency
    // resourceDirs.add("src/nativeMain/customResources") // Optional extra resources
}

The plugin automatically:

• Applies Kotlin Multiplatform with the correct host target (macOS, Linux, or Windows).
• Attaches the shared engine (:engine) and shared asset bundle (:demos:shared-assets).
• Enables required language features and experimental opt-ins.
• Configures a native executable named after applicationName that launches the provided entryPoint.

Run ./gradlew :demos:<name>:assemble after updating the module to confirm it still builds and produces the expected executable.

Project Layout

engine/             # Shared engine library (Kotlin/Native)
demos/              # Individual demo executables
  fireworks/
  asteroids/
  breakout/
  boids/
  destructible_sprite/
  balls/
  mandelbrot/
  bejewelled/
  sample_app/
  dungeon_warping/
  shared-assets/
games/              # Game executables (pixel shooter, etc.)

Disclaimer

~~Performance is shit =)~~

~~I blame garbage collector for it. Probably will do profiling and optimization.~~

I've made some optimizations with some help from Kotlin native team. Now sample app runs with stable 80 fps after short worm-up.

~~Will do an additional step after kgl updates to 1.3.50 version of kotlin-multiplatform.~~

Port is not fully complete:

• PNG sprite loading not yet ported
• Texture pack support are not ported
• Here and there you may find a missing function
• All unnecessary UInts replaced with Ints

But the core functionality is there.