@cesium/engine/Source/Core/pointInsideTriangle.js

CesiumJS is a JavaScript library for creating 3D globes and 2D maps in a web browser without a plugin.

import barycentricCoordinates from "./barycentricCoordinates.js";
import Cartesian3 from "./Cartesian3.js";
import defined from "./defined.js";

const scratchBarycentricCoords = new Cartesian3();

/**
 * Determines if a point is inside a triangle.
 *
 * @function pointInsideTriangle
 *
 * @param {Cartesian2|Cartesian3} point The point to test.
 * @param {Cartesian2|Cartesian3} p0 The first point of the triangle.
 * @param {Cartesian2|Cartesian3} p1 The second point of the triangle.
 * @param {Cartesian2|Cartesian3} p2 The third point of the triangle.
 * @returns {boolean} <code>true</code> if the point is inside the triangle; otherwise, <code>false</code>.
 *
 * @example
 * // Returns true
 * const p = new Cesium.Cartesian2(0.25, 0.25);
 * const b = Cesium.pointInsideTriangle(p,
 *   new Cesium.Cartesian2(0.0, 0.0),
 *   new Cesium.Cartesian2(1.0, 0.0),
 *   new Cesium.Cartesian2(0.0, 1.0));
 */
function pointInsideTriangle(point, p0, p1, p2) {
  const coords = barycentricCoordinates(
    point,
    p0,
    p1,
    p2,
    scratchBarycentricCoords,
  );
  if (!defined(coords)) {
    return false;
  }
  return coords.x > 0.0 && coords.y > 0.0 && coords.z > 0;
}
export default pointInsideTriangle;