setupClipping( builder ) {

		if ( builder.clippingContext === null ) return null;

		const { unionPlanes, intersectionPlanes } = builder.clippingContext;

		let result = null;

		if ( unionPlanes.length > 0 || intersectionPlanes.length > 0 ) {

			const samples = builder.renderer.samples;

			if ( this.alphaToCoverage && samples > 1 ) {

				// to be added to flow when the color/alpha value has been determined
				result = clippingAlpha();

			} else {

				builder.stack.add( clipping() );

			}

		}

		return result;

	}
Setups the clipping node.

@param {NodeBuilder} builder - The current node builder.
@return {ClippingNode} The clipping node.