Animation

GCubeSDK is using the same principles like threejs when it comes to animation, by using AnimationClip. A clip is a collection of KeyframeTracks. A track is a map of time : value pairs for one certain property, for example position.y or Hips.quaternion.y. An AnimationMixer plays this clip on one object. Call mixer->update every frame in order to play the animation. The mixer is managing all the clips, tracks, and binds them to the properties. Use one mixer per object. An object can store several clips, such as walk and jump. Play one clip at a time.

Relevant Classes

When using the GLTFLoader, things like bones and animation will be extracted and converted into clips, actions, interpolants etc..

Play an animation

Export GLTF or GLB. Put the file in data/. Details are in Assets.

GLTFLoader creates the group, the skinned mesh, the skeleton, the bones, and the clips. You create the mixer and select a clip.

GLTFLoader*     loader  = new GLTFLoader();
Group*          obj     = loader->load("person.glb");
AnimationMixer* mixer   = new AnimationMixer(obj);

scene->add(obj);
mixer->clipAction((AnimationClip*) obj->animations[0]);

while (1)
{
    //  ...
    mixer->update(1.0f / 30.0f);
    engine->render(scene, camera);
}

animations[0] is the first clip stored in the file. DemoGLTFAnimation loads the same model three times. Each copy has its own mixer, so each copy can play on its own.

Interpolators

Each track is a list of keys. The interpolant is samples a value when the current time sits between two keys. The picture uses the same four keys for all three modes.

DemoKeyframeTrack shows these three modes on cubes.

Other

The same mixer plays clips that did not come from a model. DemoAnimationMixer simulates a bounce once, stores the height and the squash as tracks, and plays that clip on each ball. The balls are a normal Mesh. They have no skeleton.