From 4d7bcd45043201961743e79925c91ba003c048ef Mon Sep 17 00:00:00 2001
From: Alex de Mulder <alexdemulder@gmail.com>
Date: Wed, 14 Jan 2015 11:41:47 +0100
Subject: [PATCH] - Added condition to Repulsion similar to BarnesHut to ensure
 nodes do not overlap.

---
 HISTORY.md                                   | 1 +
 dist/vis.js                                  | 8 +++++++-
 lib/network/mixins/physics/RepulsionMixin.js | 8 +++++++-
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/HISTORY.md b/HISTORY.md
index 620585b0..3736f185 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -17,6 +17,7 @@ http://visjs.org
 - Made the node/edge selected by the popup system the same as selected by the click-to-select system. Thank you @pavlos256!
 - Improved edit edge control nodes positions, altered style a little.
 - Fixed issue #564 by resetting state to initial when no callback is performed in the return function.
+- Added condition to Repulsion similar to BarnesHut to ensure nodes do not overlap.
 
 ### Timeline
 
diff --git a/dist/vis.js b/dist/vis.js
index 3b2c716f..f759647e 100644
--- a/dist/vis.js
+++ b/dist/vis.js
@@ -29990,6 +29990,12 @@ return /******/ (function(modules) { // webpackBootstrap
         dy = node2.y - node1.y;
         distance = Math.sqrt(dx * dx + dy * dy);
 
+        // same condition as BarnesHut, making sure nodes are never 100% overlapping.
+        if (distance == 0) {
+          distance = 0.1*Math.random();
+          dx = distance;
+        }
+
         minimumDistance = (combinedClusterSize == 0) ? nodeDistance : (nodeDistance * (1 + combinedClusterSize * this.constants.clustering.distanceAmplification));
         var a = a_base / minimumDistance;
         if (distance < 2 * minimumDistance) {
@@ -29999,13 +30005,13 @@ return /******/ (function(modules) { // webpackBootstrap
           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 / Math.max(distance,0.01*minimumDistance);
 
           fx = dx * repulsingForce;
           fy = dy * repulsingForce;
-
           node1.fx -= fx;
           node1.fy -= fy;
           node2.fx += fx;
diff --git a/lib/network/mixins/physics/RepulsionMixin.js b/lib/network/mixins/physics/RepulsionMixin.js
index e3b56ac7..4b3ef6ac 100644
--- a/lib/network/mixins/physics/RepulsionMixin.js
+++ b/lib/network/mixins/physics/RepulsionMixin.js
@@ -31,6 +31,12 @@ exports._calculateNodeForces = function () {
       dy = node2.y - node1.y;
       distance = Math.sqrt(dx * dx + dy * dy);
 
+      // same condition as BarnesHut, making sure nodes are never 100% overlapping.
+      if (distance == 0) {
+        distance = 0.1*Math.random();
+        dx = distance;
+      }
+
       minimumDistance = (combinedClusterSize == 0) ? nodeDistance : (nodeDistance * (1 + combinedClusterSize * this.constants.clustering.distanceAmplification));
       var a = a_base / minimumDistance;
       if (distance < 2 * minimumDistance) {
@@ -40,13 +46,13 @@ 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 / Math.max(distance,0.01*minimumDistance);
 
         fx = dx * repulsingForce;
         fy = dy * repulsingForce;
-
         node1.fx -= fx;
         node1.fy -= fy;
         node2.fx += fx;