setup( /*builder*/ ) {

		const projectionMatrix = ( this.projectionMatrix === null ) ? cameraProjectionMatrix : uniform( this.projectionMatrix );

		const previousModelViewMatrix = this.previousCameraViewMatrix.mul( this.previousModelWorldMatrix );

		const clipPositionCurrent = projectionMatrix.mul( modelViewMatrix ).mul( positionLocal );
		const clipPositionPrevious = this.previousProjectionMatrix.mul( previousModelViewMatrix ).mul( positionPrevious );

		const ndcPositionCurrent = clipPositionCurrent.xy.div( clipPositionCurrent.w );
		const ndcPositionPrevious = clipPositionPrevious.xy.div( clipPositionPrevious.w );

		const velocity = sub( ndcPositionCurrent, ndcPositionPrevious );

		return velocity;

	}
Implements the velocity computation based on the previous and current vertex data.

@param {NodeBuilder} builder - A reference to the current node builder.
@return {Node<vec2>} The motion vector.