accumulate( accuIndex, weight ) {

		// note: happily accumulating nothing when weight = 0, the caller knows
		// the weight and shouldn't have made the call in the first place

		const buffer = this.buffer,
			stride = this.valueSize,
			offset = accuIndex * stride + stride;

		let currentWeight = this.cumulativeWeight;

		if ( currentWeight === 0 ) {

			// accuN := incoming * weight

			for ( let i = 0; i !== stride; ++ i ) {

				buffer[ offset + i ] = buffer[ i ];

			}

			currentWeight = weight;

		} else {

			// accuN := accuN + incoming * weight

			currentWeight += weight;
			const mix = weight / currentWeight;
			this._mixBufferRegion( buffer, offset, 0, mix, stride );

		}

		this.cumulativeWeight = currentWeight;

	}
Accumulates data in the `incoming` region into `accu<i>`.

@param {number} accuIndex - The accumulation index.
@param {number} weight - The weight.