@phaserjs/phaser/geom/triangle/GetTrianglePoints.js

Phaser 4

/**
 * @author       Richard Davey <rich@photonstorm.com>
 * @copyright    2020 Photon Storm Ltd.
 * @license      {@link https://opensource.org/licenses/MIT|MIT License}
 */
import { GetLineLength } from "../line/GetLineLength";
import { GetTriangleEdges } from "./GetTriangleEdges";
import { Vec2 } from "../../math/vec2/Vec2";
export function GetTrianglePoints(triangle, quantity, stepRate, out = []) {
  const [line1, line2, line3] = GetTriangleEdges(triangle);
  const length1 = GetLineLength(line1);
  const length2 = GetLineLength(line2);
  const length3 = GetLineLength(line3);
  const perimeter = length1 + length2 + length3;
  if (!quantity) {
    quantity = perimeter / stepRate;
  }
  for (let i = 0; i < quantity; i++) {
    let p = perimeter * (i / quantity);
    let localPosition = 0;
    let point;
    if (p < length1) {
      localPosition = p / length1;
      const { x1, y1, x2, y2 } = line1;
      point = new Vec2(x1 + (x2 - x1) * localPosition, y1 + (y2 - y1) * localPosition);
    } else if (p > length1 + length2) {
      p -= length1 + length2;
      localPosition = p / length3;
      const { x1, y1, x2, y2 } = line3;
      point = new Vec2(x1 + (x2 - x1) * localPosition, y1 + (y2 - y1) * localPosition);
    } else {
      p -= length1;
      localPosition = p / length2;
      const { x1, y1, x2, y2 } = line2;
      point = new Vec2(x1 + (x2 - x1) * localPosition, y1 + (y2 - y1) * localPosition);
    }
    out.push(point);
  }
  return out;
}