kogot

kogot is an experimental Kotlin/Native binding for Godot 4.6+ via the GDExtension interface. The goal is to bring Kotlin to Godot with the same philosophy as godot-rust/gdext — a mechanical, verifiable projection of Godot's official API contract, with a minimal generated runtime layer.

What Works (Early Stage)

Feature	Status
Engine classes (codegen from Godot JSON API)	~2000+ files generated. Done
Builtin types: String, Array, Dictionary, Variant	Done. Pending improvements
Class registration (register(), freeInstance(), createInstance())	Done. Pending processor
MethodBind calls via invoke() with Variant conversion	Pending
Properties (@Export annotation)	Pending
Virtual methods (NodeVirtualCalls, NodeVirtualDispatcher)	In progress
Signals (Signal0 — zero args)	Design
Signals with params (Signal1..22)	Design

Architecture

User Code (@Godot class)
    ↓
processor/KogotProcessor (KSP annotation processing)
    ↓
codegen/ → kotlin-native/api/build/generated/ (2000+ generated .kt files)
    ↓
kotlin-native/binding/ (runtime class registration)
    ↓
kotlin-native/ffi/ (GDExtension FFI via cinterop)
    ↓
Godot Engine (C++)

Project Structure

kogot/
├── analysis/              # KSP backend-agnostic metadata extraction
├── codegen/               # Godot API model + KotlinPoet code generation
├── processor/             # KSP compiler plugin (annotation processing)
├── kotlin-native/
│   ├── annotations/       # User annotations: @Godot, @Export, @Rpc, @Tool
│   ├── api/               # Generated Godot API classes (build/generated/)
│   ├── binding/           # Runtime binding registration
│   ├── ffi/               # Low-level FFI to Godot C functions via .def cinterop
│   └── runtime/           # Kotlin/Native runtime support
├── jvm-ffm/               # Java FFM integration (incomplete)
├── build-logic/           # Gradle convention plugins (including jextract-gradle-plugin)
├── mi-juego-prueba/       # Test Godot project
└── docs/                  # Design docs, roadmap, and exploration notes

Generated API Sample

// Generated from Godot's JSON API — DO NOT EDIT
class GodotString(rawPtr: COpaquePointer?) : GodotNative, AutoCloseable {
    constructor()  // empty string
    constructor(from: GodotString)  // copy constructor
    constructor(value: String)  // from Kotlin String
    override fun close() { ... }
}

// Generated Node class with full Godot API projection
public open class Node(nativePtr: COpaquePointer) : GodotObject(nativePtr) {
    public var name: StringName
    public var uniqueNameInOwner: Boolean
    public var sceneFilePath: GodotString
    // ... full Godot Node API
}

User Annotations

@Godot class MyNode(nativePtr: COpaquePointer) : Node(nativePtr) {
    @Export var health: Int = 100

    companion object {
        val isDeadSignal: Signal0 = signal("is_dead")
        val healthSignal: Signal1<Int> = signal("health", param<Int>("value"))
    }
}

Build

./gradlew assemble

Roadmap

Follow the project board for updates.

References

• godot-rust/gdext — Reference binding design
• Java 25 SE – Foreign Function and Memory API
• Kotlin/Native Guide
• Godot 4.6 GDExtension docs