src/worker/VolumeModifier.js

import { ConstructiveSolidGeometry } from "../volume/csg/ConstructiveSolidGeometry";
import { SDFReviver } from "../volume/sdf/SDFReviver";
import { ModificationResponse } from "./messages/ModificationResponse";
import { DataProcessor } from "./DataProcessor";

/**
 * A modifier that applies CSG operations to Hermite data.
 */

export class VolumeModifier extends DataProcessor {

	/**
	 * Constructs a new Hermite data modifier.
	 */

	constructor() {

		super();

		/**
		 * A container for the data that will be returned to the main thread.
		 *
		 * @type {ModificationResponse}
		 */

		this.response = new ModificationResponse();

		/**
		 * An SDF.
		 *
		 * @type {SignedDistanceFunction}
		 * @private
		 */

		this.sdf = null;

	}

	/**
	 * Prepares a response that can be send back to the main thread.
	 *
	 * Should be used together with {@link VolumeModifier#createTransferList}.
	 *
	 * @return {ModificationResponse} A response.
	 */

	respond() {

		// The container group contains the modified data.
		const response = super.respond();

		// Send the SDF back as it may contain transferable data.
		response.sdf = (this.sdf !== null) ? this.sdf.serialize() : null;

		return response;

	}

	/**
	 * Creates a list of transferable items.
	 *
	 * @param {Array} [transferList] - An optional target list. The transferable items will be added to this list.
	 * @return {Transferable[]} The transfer list.
	 */

	createTransferList(transferList = []) {

		super.createTransferList(transferList);

		return (this.sdf !== null) ? this.sdf.createTransferList(transferList) : transferList;

	}

	/**
	 * Modifies the given Hermite data using the provided SDF.
	 *
	 * @param {ModificationRequest} request - A modification request.
	 */

	process(request) {

		// Adopt the provided data.
		const data = super.process(request).getData();

		// Revive the SDF.
		const sdf = this.sdf = SDFReviver.revive(request.sdf);

		// The resulting data is uncompressed.
		const result = ConstructiveSolidGeometry.run(request.cellPosition, request.cellSize, data, sdf);

		// Overwrite the data and compress it.
		super.data = (result !== null) ? result.compress() : null;

		return this;

	}

}