setup() {

		const bumpScale = this.scaleNode !== null ? this.scaleNode : 1;
		const dHdxy = dHdxy_fwd( { textureNode: this.textureNode, bumpScale } );

		return perturbNormalArb( {
			surf_pos: positionView,
			surf_norm: normalView,
			dHdxy
		} );

	}
Controls the intensity of the bump effect.

@type {?Node<float>}
@default null