bind( skeleton, bindMatrix ) {

		this.skeleton = skeleton;

		if ( bindMatrix === undefined ) {

			this.updateMatrixWorld( true );

			this.skeleton.calculateInverses();

			bindMatrix = this.matrixWorld;

		}

		this.bindMatrix.copy( bindMatrix );
		this.bindMatrixInverse.copy( bindMatrix ).invert();

	}
Binds the given skeleton to the skinned mesh.

@param {Skeleton} skeleton - The skeleton to bind.
@param {Matrix4} [bindMatrix] - The bind matrix. If no bind matrix is provided,
the skinned mesh's world matrix will be used instead.