polygonjs-engine/src/engine/expressions/methods/centroid.ts

node-based webgl 3D engine https://polygonjs.com

/**
 * Returns the centroid of a geometry, or the component of the centroid.
 *
 * @remarks
 * It takes 1 or 2 arguments.
 *
 * centroid(<input_index_or_node_path\>, <vector_component\>)
 *
 * - **<input_index_or_node_path\>** is a number or a string
 * - **<vector_component\>** is a string, either 'x', 'y' or 'z'
 *
 * ## Usage
 *
 * - `centroid(0)` - returns the centroid of the input node, as a THREE.Box3
 * - `centroid('/geo1/box')` - returns the centroid of the node /geo1/box, as a THREE.Box3
 * - `centroid('/geo1/box', 'x')` - returns the x component of centroid of the bbox, as a number
 *
 */
import {BaseMethod} from './_Base';
import {MethodDependency} from '../MethodDependency';
import {GeometryContainer} from '../../containers/Geometry';
import {Vector3Like} from '../../../types/GlobalTypes';
export class CentroidExpression extends BaseMethod {
	protected _require_dependency = true;
	static required_arguments() {
		return [
			['string', 'path to node'],
			['string', 'component_name, x,y or z'],
		];
	}

	find_dependency(index_or_path: number | string): MethodDependency | null {
		return this.create_dependency_from_index_or_path(index_or_path);
	}

	process_arguments(args: any[]): Promise<any> {
		return new Promise(async (resolve, reject) => {
			if (args.length >= 1) {
				const index_or_path = args[0];
				const component_name: undefined | keyof Vector3Like = args[1];
				let container: GeometryContainer | null = null;
				try {
					container = (await this.get_referenced_node_container(index_or_path)) as GeometryContainer;
				} catch (e) {
					reject(e);
				}

				if (container) {
					const bbox = container.boundingBox();
					const center = bbox.min.clone().add(bbox.max).multiplyScalar(0.5);

					if (component_name) {
						const value = center[component_name];
						if (value != null) {
							resolve(value);
						} else {
							resolve(0);
						}
					} else {
						resolve(center);
					}
				}
			} else {
				resolve(0);
			}
		});
	}
}