saveOriginalState() {

		const binding = this.binding;

		const buffer = this.buffer,
			stride = this.valueSize,

			originalValueOffset = stride * this._origIndex;

		binding.getValue( buffer, originalValueOffset );

		// accu[0..1] := orig -- initially detect changes against the original
		for ( let i = stride, e = originalValueOffset; i !== e; ++ i ) {

			buffer[ i ] = buffer[ originalValueOffset + ( i % stride ) ];

		}

		// Add to identity for additive
		this._setIdentity();

		this.cumulativeWeight = 0;
		this.cumulativeWeightAdditive = 0;

	}
Remembers the state of the bound property and copy it to both accus.