plotboilerplate/src/ts/utils/algorithms/clearDuplicateVertices.ts

A simple javascript plotting boilerplate for 2d stuff.

/**
 * Remove duplicate vertices (2d) from an array.
 *
 * This method war taken and refactored from an older demo.
 *
 * @author   Ikaros Kappler
 * @date     2021-07-13
 * @modified 2023-10-28 Refactored and ported to Typescript.
 * @modified 2024-12-17 Simplified this method to work with generic sub types of XYCoords as well.
 * @version  1.0.1
 */

import { geomutils } from "../../geomutils";
import { XYCoords } from "../../interfaces";

const EPS: number = 0.000001;

/**
 * Filter the array and clear all duplicates.
 *
 * The original array is left unchanged. The vertices in the array are not cloned.
 *
 * @param {XYCoords[]} vertices
 * @param {number=EPS} epsilon
 * @return {Vertex[]}
 */
export const clearDuplicateVertices = <T extends XYCoords>(vertices: T[], epsilon?: number) => {
  if (typeof epsilon === "undefined") {
    epsilon = EPS;
  }
  const result: Array<T> = [];
  for (var i = 0; i < vertices.length; i++) {
    if (!containsElementFrom(vertices, vertices[i], i + 1, epsilon)) {
      result.push(vertices[i]);
    }
  }
  return result;
};

const isCloseTo = <T extends XYCoords>(vertA: T, vertB: T, eps: number): boolean => {
  // return vertA.distance(vertB) < eps;
  return geomutils.dist4(vertA.x, vertA.y, vertB.x, vertB.y) < eps;
};

const containsElementFrom = <T extends XYCoords>(vertices: Array<T>, vertex: T, fromIndex: number, epsilon: number): boolean => {
  for (var i = fromIndex; i < vertices.length; i++) {
    if (isCloseTo(vertices[i], vertex, epsilon)) {
      return true;
    }
  }
  return false;
};