ngraph.forcelayout3d/lib/bounds.js

Force directed graph layout in 3d

module.exports = function (bodies, settings) {
  var random = require('ngraph.random').random(42);
  var boundingBox =  { x1: 0, y1: 0, z1: 0, x2: 0, y2: 0, z2: 0 };

  return {
    box: boundingBox,

    update: updateBoundingBox,

    reset : function () {
      boundingBox.x1 = boundingBox.y1 = 0;
      boundingBox.x2 = boundingBox.y2 = 0;
      boundingBox.z1 = boundingBox.z2 = 0;
    },

    getBestNewPosition: function (neighbors) {
      var graphRect = boundingBox;

      var baseX = 0, baseY = 0, baseZ = 0;

      if (neighbors.length) {
        for (var i = 0; i < neighbors.length; ++i) {
          baseX += neighbors[i].pos.x;
          baseY += neighbors[i].pos.y;
          baseZ += neighbors[i].pos.z;
        }

        baseX /= neighbors.length;
        baseY /= neighbors.length;
        baseZ /= neighbors.length;
      } else {
        baseX = (graphRect.x1 + graphRect.x2) / 2;
        baseY = (graphRect.y1 + graphRect.y2) / 2;
        baseZ = (graphRect.z1 + graphRect.z2) / 2;
      }

      var springLength = settings.springLength;
      return {
        x: baseX + random.next(springLength) - springLength / 2,
        y: baseY + random.next(springLength) - springLength / 2,
        z: baseZ + random.next(springLength) - springLength / 2
      };
    }
  };

  function updateBoundingBox() {
    var i = bodies.length;
    if (i === 0) { return; } // don't have to wory here.

    var x1 = Number.MAX_VALUE,
        y1 = Number.MAX_VALUE,
        z1 = Number.MAX_VALUE,
        x2 = Number.MIN_VALUE,
        y2 = Number.MIN_VALUE,
        z2 = Number.MIN_VALUE;

    while(i--) {
      // this is O(n), could it be done faster with quadtree?
      // how about pinned nodes?
      var body = bodies[i];
      if (body.isPinned) {
        body.pos.x = body.prevPos.x;
        body.pos.y = body.prevPos.y;
        body.pos.z = body.prevPos.z;
      } else {
        body.prevPos.x = body.pos.x;
        body.prevPos.y = body.pos.y;
        body.prevPos.z = body.pos.z;
      }
      if (body.pos.x < x1) {
        x1 = body.pos.x;
      }
      if (body.pos.x > x2) {
        x2 = body.pos.x;
      }
      if (body.pos.y < y1) {
        y1 = body.pos.y;
      }
      if (body.pos.y > y2) {
        y2 = body.pos.y;
      }
      if (body.pos.z < z1) {
        z1 = body.pos.z;
      }
      if (body.pos.z > z2) {
        z2 = body.pos.z;
      }
    }

    boundingBox.x1 = x1;
    boundingBox.x2 = x2;
    boundingBox.y1 = y1;
    boundingBox.y2 = y2;
    boundingBox.z1 = z1;
    boundingBox.z2 = z2;
  }
};