spine-runtimes/docs/project-description.md

Project: Spine Runtimes

Multi-language runtime libraries for Spine 2D skeletal animations. The project provides core runtimes for different programming languages and integrations for various game engines and frameworks.

Core Runtimes (Language-specific implementations)

spine-libgdx (Java) - Reference Implementation

• Build: ./gradlew build
• Publish: ./gradlew publishToMavenLocal
• All other runtimes are ports of this reference implementation

spine-cpp (C++)

• Build: cmake -B build && cmake --build build
• Port of spine-libgdx
• Uses custom RTTI (no C++ exceptions/RTTI)

spine-csharp (C#)

• Build: msbuild spine-csharp.csproj or dotnet build
• Port of spine-libgdx
• Targets .NET Framework 4.8

spine-ts (TypeScript/JavaScript)

• Build: npm install && npm run build
• Dev: npm run dev
• Port of spine-libgdx
• Core module at spine-ts/spine-core/

spine-haxe (Haxe)

• Build: ./build.sh
• Port of spine-libgdx
• Uses Haxelib package manager

spine-c (C)

• Build: cmake -B build && cmake --build build
• Actively maintained C implementation
• Different structure from other runtimes due to C language constraints

Integration Runtimes (Engine/Framework-specific)

Using spine-cpp:

• spine-cocos2dx - Cocos2d-x engine
• spine-flutter - Flutter (via spine-cpp-lite C wrapper + Dart FFI)
• spine-glfw - GLFW/OpenGL example
• spine-godot - Godot Engine
• spine-ios - iOS native (via spine-cpp-lite C wrapper + Swift codegen)
• spine-sdl - SDL (optional, can use spine-c)
• spine-sfml/cpp - SFML C++ version
• spine-ue - Unreal Engine 4.27-5.4

Using spine-csharp:

• spine-unity - Unity game engine
• spine-monogame - MonoGame framework
• spine-xna - XNA Framework (legacy)

Using spine-libgdx:

• spine-android - Android native

Using spine-c:

• spine-sdl - SDL (optional, can use spine-cpp)
• spine-sfml/c - SFML C version

Using spine-core (TypeScript):

• spine-canvas - HTML5 Canvas
• spine-webgl - Direct WebGL
• spine-phaser - Phaser.js (v3 & v4)
• spine-pixi - PixiJS (v7 & v8)
• spine-threejs - Three.js
• spine-player - Embeddable web player
• spine-canvaskit - Skia CanvasKit
• spine-webcomponents - Web Components

Special Cases

spine-cpp-lite

• C wrapper around spine-cpp for FFI-friendly bindings
• Located in spine-cpp/spine-cpp-lite/
• Provides simplified C API consumed by:
  • spine-flutter (via Dart FFI)
  • spine-ios (via Swift code generation)

Commands Summary

• Check spine-cpp: cd spine-cpp && cmake -B build && cmake --build build
• Check spine-ts: cd spine-ts && npm install && npm run build
• Check spine-libgdx: cd spine-libgdx && ./gradlew build
• Check spine-csharp: cd spine-csharp && msbuild spine-csharp.csproj
• Check spine-c: cd spine-c && cmake -B build && cmake --build build

Development Workflow

• All changes start in spine-libgdx (reference implementation)
• Port changes to other core runtimes using git diffs
• Integration runtimes automatically inherit changes from their core runtime

Type System Documentation

For a complete reference of all types in the Spine runtime, see spine-runtimes-types.md. To regenerate this documentation, run: node docs/generate-type-hierarchy.js

Spine Type System Overview (from spine-libgdx)

Core Types

• Skeleton - Stores the current pose for a skeleton
• SkeletonData - Stores setup pose and stateless data
• Bone/BoneData - Current pose and setup data for bones
• Slot/SlotData - Manages attachments and drawing order
• Skin - Collection of attachments keyed by slot and name

Animation System

• Animation - List of timelines to animate skeleton pose
• AnimationState - Applies animations, handles mixing and layering
• AnimationStateData - Stores mix (crossfade) durations

Attachment Types (Visual Elements)

• Attachment - Base class for all attachments
• RegionAttachment - Textured quadrilateral
• MeshAttachment - Textured mesh with vertices
• BoundingBoxAttachment - Polygon for hit detection
• ClippingAttachment - Polygon for clipping rendering
• PathAttachment - Composite Bezier curve
• PointAttachment - Single point with rotation
• SkeletonAttachment - Nested skeleton

Constraint Types

• IkConstraint - Inverse kinematics (1-2 bones)
• TransformConstraint - Copy/mix transform from target
• PathConstraint - Follow path attachment
• PhysicsConstraint - Apply physics simulation

Pose System (new in 4.2+)

• Pose - Interface for pose data
• BoneLocal/BonePose - Local and world bone transforms
• Update - Interface for updateable elements
• PosedActive/PosedData - Base classes for runtime/setup data

Other Core Types

• Event/EventData - Animation events system
• Sequence - Frame-by-frame texture sequences
• SkeletonBounds - Hit detection utilities
• SkeletonLoader - Base for JSON/Binary loaders