trip.three/lib/util/closestPointToEdge.js

Three.js addon for Trip

'use strict';

var THREE = require('three');
var rayFromWorldAndCamera = require('./rayFromWorldAndCamera');

module.exports = function (worldPos, edge, camera) {
  var ray = rayFromWorldAndCamera(worldPos, camera);

  var from = edge[0];
  var direction = new THREE.Vector3().subVectors(edge[1], edge[0]);

  // http://softsurfer.com/Archive/algorithm_0106/algorithm_0106.htm
  var u = direction.clone().normalize();
  var v = ray.direction;

  var w0 = new THREE.Vector3().subVectors(from, ray.origin);
  var a = u.dot(u);
  var b = u.dot(v);
  var c = v.dot(v);
  var d = u.dot(w0);
  var e = v.dot(w0);

  var sc = (b * e - c * d) / (a * c - b * b);
  // const tc = (a*e - b*d)/(a*c - b*b);

  var psc = new THREE.Vector3().addVectors(from, u.clone().multiplyScalar(sc));
  // const qtc = new THREE.Vector3().addVectors(mouseRay.origin, v.clone().multiplyScalar(tc));

  // Check if one the edge or outside by checking the distance to the endpoints
  // is less than the length of the edge
  var l = direction.length();
  if (new THREE.Vector3().subVectors(psc, edge[0]).length() <= l && new THREE.Vector3().subVectors(psc, edge[1]).length() <= l) {
    return psc;
  } else {
    return null;
  }
};