isNormalizedNormalAttribute( normal ) {

		const cache = this.cache;

		if ( cache.attributesNormalized.has( normal ) ) return false;

		const v = new Vector3();

		for ( let i = 0, il = normal.count; i < il; i ++ ) {

			// 0.0005 is from glTF-validator
			if ( Math.abs( v.fromBufferAttribute( normal, i ).length() - 1.0 ) > 0.0005 ) return false;

		}

		return true;

	}
Checks if normal attribute values are normalized.

@param {BufferAttribute} normal
@returns {boolean}