jrtechs-vis/lib/network/modules/components/edges/util/BezierEdgeBase.js

/**
 * Created by Alex on 3/20/2015.
 */

import EdgeBase from './EdgeBase'

class BezierEdgeBase extends EdgeBase {
  constructor(options, body, labelModule) {
    super(options, body, labelModule);
  }

  /**
   * This function uses binary search to look for the point where the bezier curve crosses the border of the node.
   *
   * @param nearNode
   * @param ctx
   * @param viaNode
   * @param nearNode
   * @param ctx
   * @param viaNode
   * @param nearNode
   * @param ctx
   * @param viaNode
   */
  _findBorderPositionBezier(nearNode, ctx, viaNode = this._getViaCoordinates()) {
    var maxIterations = 10;
    var iteration = 0;
    var low = 0;
    var high = 1;
    var pos, angle, distanceToBorder, distanceToPoint, difference;
    var threshold = 0.2;
    var node = this.to;
    var from = false;
    if (nearNode.id === this.from.id) {
      node = this.from;
      from = true;
    }

    while (low <= high && iteration < maxIterations) {
      var middle = (low + high) * 0.5;

      pos = this.getPoint(middle, viaNode);
      angle = Math.atan2((node.y - pos.y), (node.x - pos.x));
      distanceToBorder = node.distanceToBorder(ctx, angle);
      distanceToPoint = Math.sqrt(Math.pow(pos.x - node.x, 2) + Math.pow(pos.y - node.y, 2));
      difference = distanceToBorder - distanceToPoint;
      if (Math.abs(difference) < threshold) {
        break; // found
      }
      else if (difference < 0) { // distance to nodes is larger than distance to border --> t needs to be bigger if we're looking at the to node.
        if (from === false) {
          low = middle;
        }
        else {
          high = middle;
        }
      }
      else {
        if (from === false) {
          high = middle;
        }
        else {
          low = middle;
        }
      }

      iteration++;
    }
    pos.t = middle;

    return pos;
  }



  /**
   * Calculate the distance between a point (x3,y3) and a line segment from
   * (x1,y1) to (x2,y2).
   * http://stackoverflow.com/questions/849211/shortest-distancae-between-a-point-and-a-line-segment
   * @param {number} x1
   * @param {number} y1
   * @param {number} x2
   * @param {number} y2
   * @param {number} x3
   * @param {number} y3
   * @private
   */
  _getDistanceToBezierEdge(x1, y1, x2, y2, x3, y3, via) { // x3,y3 is the point
    let xVia, yVia;
    xVia = via.x;
    yVia = via.y;
    let minDistance = 1e9;
    let distance;
    let i, t, x, y;
    let lastX = x1;
    let lastY = y1;
    for (i = 1; i < 10; i++) {
      t = 0.1 * i;
      x = Math.pow(1 - t, 2) * x1 + (2 * t * (1 - t)) * xVia + Math.pow(t, 2) * x2;
      y = Math.pow(1 - t, 2) * y1 + (2 * t * (1 - t)) * yVia + Math.pow(t, 2) * y2;
      if (i > 0) {
        distance = this._getDistanceToLine(lastX, lastY, x, y, x3, y3);
        minDistance = distance < minDistance ? distance : minDistance;
      }
      lastX = x;
      lastY = y;
    }

    return minDistance;
  }
}

export default BezierEdgeBase;