copyAt( index1, attribute, index2 ) {

		index1 *= this.itemSize;
		index2 *= attribute.itemSize;

		for ( let i = 0, l = this.itemSize; i < l; i ++ ) {

			this.array[ index1 + i ] = attribute.array[ index2 + i ];

		}

		return this;

	}
Copies a vector from the given buffer attribute to this one. The start
and destination position in the attribute buffers are represented by the
given indices.

@param {number} index1 - The destination index into this buffer attribute.
@param {BufferAttribute} attribute - The buffer attribute to copy from.
@param {number} index2 - The source index into the given buffer attribute.
@return {BufferAttribute} A reference to this instance.