- Fixed error in repulsion physics model.

- Improved physics handling for smoother network simulation.

HISTORY.md

@@ -19,6 +19,8 @@ http://visjs.org
 - Fixed bug where box shaped nodes did not use hover color.
 - Fixed Locales docs.
 - When hovering over a node that does not have a title, the title of one of the connected edges that HAS a title is no longer shown.
+- Fixed error in repulsion physics model.
+- Improved physics handling for smoother network simulation.
 
 ### Graph2d
 

lib/network/Network.js

@@ -35,6 +35,7 @@ function Network (container, data, options) {
     throw new SyntaxError('Constructor must be called with the new operator');
   }
 
+  this._determineBrowserMethod();
   this._initializeMixinLoaders();
 
   // create variables and set default values
@@ -43,8 +44,8 @@ function Network (container, data, options) {
   // render and calculation settings
   this.renderRefreshRate = 60;                         // hz (fps)
   this.renderTimestep = 1000 / this.renderRefreshRate; // ms -- saves calculation later on
-  this.renderTime = 0.5 * this.renderTimestep;         // measured time it takes to render a frame
-  this.maxPhysicsTicksPerRender = 3;                   // max amount of physics ticks per render step.
+  this.renderTime = 0;                                 // measured time it takes to render a frame
+  this.physicsTime = 0;                                 // measured time it takes to render a frame
   this.physicsDiscreteStepsize = 0.50;                 // discrete stepsize of the simulation
 
   this.initializing = true;
@@ -349,6 +350,22 @@ function Network (container, data, options) {
 // Extend Network with an Emitter mixin
 Emitter(Network.prototype);
 
+
+Network.prototype._determineBrowserMethod = function() {
+  var ua = navigator.userAgent.toLowerCase();
+
+  this.requiresTimeout = false;
+  if (ua.indexOf('msie 9.0') != -1) { // IE 9
+    this.requiresTimeout = true;
+  }
+  else if (ua.indexOf('safari') != -1) {  // safari
+    if (ua.indexOf('chrome') <= -1) {
+      this.requiresTimeout = true;
+    }
+  }
+}
+
+
 /**
  * Get the script path where the vis.js library is located
  *
@@ -2166,26 +2183,26 @@ Network.prototype._physicsTick = function() {
 Network.prototype._animationStep = function() {
   // reset the timer so a new scheduled animation step can be set
   this.timer = undefined;
+
   // handle the keyboad movement
   this._handleNavigation();
 
-  // this schedules a new animation step
-  this.start();
-
-  // start the physics simulation
-  var calculationTime = Date.now();
-  var maxSteps = 1;
+  var startTime = Date.now();
   this._physicsTick();
-  var timeRequired = Date.now() - calculationTime;
-  while (timeRequired < 0.9*(this.renderTimestep - this.renderTime) && maxSteps < this.maxPhysicsTicksPerRender) {
+
+  // run double speed if it is a little graph
+  if (this.renderTimestep - this.renderTime > 2*this.physicsTime) {
     this._physicsTick();
-    timeRequired = Date.now() - calculationTime;
-    maxSteps++;
   }
-  // start the rendering process
-  var renderTime = Date.now();
+
+  this.physicsTime = Date.now() - startTime;
+
+  var renderStartTime = Date.now();
   this._redraw();
-  this.renderTime = Date.now() - renderTime;
+  this.renderTime = Date.now() - renderStartTime;
+
+  // this schedules a new animation step
+  this.start();
 };
 
 if (typeof window !== 'undefined') {
@@ -2204,23 +2221,13 @@ Network.prototype.start = function() {
     }
 
     if (!this.timer) {
-      var ua = navigator.userAgent.toLowerCase();
 
-      var requiresTimeout = false;
-      if (ua.indexOf('msie 9.0') != -1) { // IE 9
-        requiresTimeout = true;
-      }
-      else if (ua.indexOf('safari') != -1) {  // safari
-        if (ua.indexOf('chrome') <= -1) {
-          requiresTimeout = true;
-        }
-      }
 
-      if (requiresTimeout == true) {
+      if (this.requiresTimeout == true) {
         this.timer = window.setTimeout(this._animationStep.bind(this), this.renderTimestep); // wait this.renderTimeStep milliseconds and perform the animation step function
       }
-      else{
-        this.timer = window.requestAnimationFrame(this._animationStep.bind(this), this.renderTimestep); // wait this.renderTimeStep milliseconds and perform the animation step function
+      else {
+        this.timer = window.requestAnimationFrame(this._animationStep.bind(this)); // wait this.renderTimeStep milliseconds and perform the animation step function
       }
     }
   }

lib/network/mixins/physics/RepulsionMixin.js

@@ -40,10 +40,9 @@ exports._calculateNodeForces = function () {
         else {
           repulsingForce = a * distance + b; // linear approx of  1 / (1 + Math.exp((distance / minimumDistance - 1) * steepness))
         }
-
         // amplify the repulsion for clusters.
         repulsingForce *= (combinedClusterSize == 0) ? 1 : 1 + combinedClusterSize * this.constants.clustering.forceAmplification;
-        repulsingForce = repulsingForce / distance;
+        repulsingForce = repulsingForce / Math.max(distance,0.01*minimumDistance);
 
         fx = dx * repulsingForce;
         fy = dy * repulsingForce;
@@ -52,6 +51,7 @@ exports._calculateNodeForces = function () {
         node1.fy -= fy;
         node2.fx += fx;
         node2.fy += fy;
+
       }
     }
   }