OpenBone.Runtime 0.3.0

OpenBone.Runtime

The OpenBone runtime for .NET: load .obone and .obonb files and play skeletons, animations and state machines.

OpenBone is open-source 2D skeletal animation: Spine-style rigging and Rive-style interactive state machines. This package is a native C# port of the reference runtime. It covers skeletons, skins, every attachment type, animation mixing, IK, transform, path and physics constraints, particles, sprite sequences, text, packed atlases, state machines, events and audio commands. It passes the cross-language OpenBone conformance suite.

The runtime does not draw anything. Each frame it gives you a draw list (vertices, UVs, triangles, texture, colour, blend mode, clipping), so you can render it with any engine. It targets netstandard2.1 and net8.0 and has no dependencies.

Install

dotnet add package OpenBone.Runtime

• State-machine scripts need a script host: add OpenBone.Scripting.Jint.
• MonoGame: OpenBone.MonoGame adds a renderer, input and sound.
• Unity: use the com.openbone.runtime package instead (see below).

Quick start

using OpenBone;

var doc = DocumentLoader.Load(File.ReadAllBytes("knight.obone"));   // or a .obonb file
var hero = new OpenBoneInstance(doc);
hero.Event += e => Console.WriteLine($"event {e.Name} at {e.Time}");
hero.AudioCommand += c => Console.WriteLine($"audio {c.Type} {c.Sound}");

hero.Play("walk");                                      // loops by default

// Once per frame:
hero.Advance(dt);
foreach (var item in hero.DrawList())
{
    // item.Vertices: world x,y pairs (y up)    item.Uvs: 0..1 (v down)    item.Indices: triangles
    // item.Texture: image or atlas page (null = untextured)    item.Color, item.Dark, item.Blend, item.Clip
}

Queue animations and change skins through AnimationState and Skeleton:

hero.Skeleton.SetSkin("default");
hero.Play("attack", loop: false);
hero.AnimationState.AddAnimation(0, "idle", loop: true);

State machines

var button = new OpenBoneInstance(DocumentLoader.Load(File.ReadAllBytes("button.obone")));
var sm = button.UseStateMachine("ui");                  // or UseStateMachine() for the first one
sm.StateChanged += s => Console.WriteLine($"{s.Layer}: {s.From} -> {s.To}");

sm.SetInput("hover", true);
sm.Fire("press");
button.Advance(dt);

// Pointer input for listeners is in skeleton space (y up). Convert from artboard pixels first:
button.ArtboardToSkeleton(px, py, out var x, out var y);
button.Pointer("down", x, y);

Without a script host, scripts attached to the document are skipped and everything else runs.

Main API

Unity

Unity users should install the com.openbone.runtime package, which includes this runtime plus an importer, components, a mesh generator, a shader and an audio bridge. In the Package Manager, choose Add package from git URL and enter:

https://github.com/UXCentury/open-bone.git#upm

Documentation

• C# runtime
• Runtime specification
• File format
• Unity package
• Changelog

License

MIT. Copyright (c) UX Century and OpenBone contributors. See LICENSE.