getSkinnedNormal( boneMatrices = this.boneMatricesNode, normal = normalLocal ) {

		const { skinIndexNode, skinWeightNode, bindMatrixNode, bindMatrixInverseNode } = this;

		const boneMatX = boneMatrices.element( skinIndexNode.x );
		const boneMatY = boneMatrices.element( skinIndexNode.y );
		const boneMatZ = boneMatrices.element( skinIndexNode.z );
		const boneMatW = boneMatrices.element( skinIndexNode.w );

		// NORMAL

		let skinMatrix = add(
			skinWeightNode.x.mul( boneMatX ),
			skinWeightNode.y.mul( boneMatY ),
			skinWeightNode.z.mul( boneMatZ ),
			skinWeightNode.w.mul( boneMatW )
		);

		skinMatrix = bindMatrixInverseNode.mul( skinMatrix ).mul( bindMatrixNode );

		return skinMatrix.transformDirection( normal ).xyz;

	}
Transforms the given vertex normal via skinning.

@param {Node} [boneMatrices=this.boneMatricesNode] - The bone matrices
@param {Node<vec3>} [normal=normalLocal] - The vertex normal in local space.
@return {Node<vec3>} The transformed vertex normal.