all files / lib/util/ LineIntersection.js

88.46% Statements 23/26
83.33% Branches 10/12
100% Functions 6/6
88.46% Lines 23/26
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112                                        23×                     11×   31×                                                                                                                 11×    
import {
  pointDistance
} from './Geometry';
 
import intersectPaths from 'path-intersection';
 
var round = Math.round,
    max = Math.max;
 
 
function circlePath(center, r) {
  var x = center.x,
      y = center.y;
 
  return [
    ['M', x, y],
    ['m', 0, -r],
    ['a', r, r, 0, 1, 1, 0, 2 * r],
    ['a', r, r, 0, 1, 1, 0, -2 * r],
    ['z']
  ];
}
 
function linePath(points) {
  var segments = [];
 
  points.forEach(function(p, idx) {
    segments.push([ idx === 0 ? 'M' : 'L', p.x, p.y ]);
  });
 
  return segments;
}
 
 
var INTERSECTION_THRESHOLD = 10;
 
function getBendpointIntersection(waypoints, reference) {
 
  var i, w;
 
  for (i = 0; (w = waypoints[i]); i++) {
 
    if (pointDistance(w, reference) <= INTERSECTION_THRESHOLD) {
      return {
        point: waypoints[i],
        bendpoint: true,
        index: i
      };
    }
  }
 
  return null;
}
 
function getPathIntersection(waypoints, reference) {
 
  var intersections = intersectPaths(circlePath(reference, INTERSECTION_THRESHOLD), linePath(waypoints));
 
  var a = intersections[0],
      b = intersections[intersections.length - 1],
      idx;
 
  if (!a) {
    // no intersection
    return null;
  }
 
  Eif (a !== b) {
 
    Iif (a.segment2 !== b.segment2) {
      // we use the bendpoint in between both segments
      // as the intersection point
 
      idx = max(a.segment2, b.segment2) - 1;
 
      return {
        point: waypoints[idx],
        bendpoint: true,
        index: idx
      };
    }
 
    return {
      point: {
        x: (round(a.x + b.x) / 2),
        y: (round(a.y + b.y) / 2)
      },
      index: a.segment2
    };
  }
 
  return {
    point: {
      x: round(a.x),
      y: round(a.y)
    },
    index: a.segment2
  };
}
 
/**
 * Returns the closest point on the connection towards a given reference point.
 *
 * @param  {Array<Point>} waypoints
 * @param  {Point} reference
 *
 * @return {Object} intersection data (segment, point)
 */
export function getApproxIntersection(waypoints, reference) {
  return getBendpointIntersection(waypoints, reference) || getPathIntersection(waypoints, reference);
}