bug fix for interaction, was missing the length property on draggingNodes

clearing forces/velocities on manually changed nodes to smooth out physics response.

lib/network/modules/PhysicsEngine.js

@@ -117,7 +117,13 @@ class PhysicsEngine {
     });
     // For identifying which nodes to send to worker thread
     this.body.emitter.on('dragStart',       (properties) => {this.draggingNodes = properties.nodes;});
-    this.body.emitter.on('dragEnd',         () => {this.draggingNodes = [];});
+    this.body.emitter.on('dragEnd',         () => {
+      // need one last update to handle the case where a drag happens
+      // and the user holds the node clicked at the final position
+      // for a time prior to releasing
+      this.updateWorkerPositions();
+      this.draggingNodes = [];
+    });
     this.body.emitter.on('destroy',         () => {
       if (this.physicsWorker) {
         this.physicsWorker.terminate();
@@ -244,8 +250,7 @@ class PhysicsEngine {
       case 'positions':
         this.stabilized = msg.data.stabilized;
         var positions = msg.data.positions;
-        // console.log('received positions', positions);
-        for (let i = 0; i < this.draggingNodes; i++) {
+        for (let i = 0; i < this.draggingNodes.length; i++) {
           delete positions[this.draggingNodes[i]];
         }
         let nodeIds = Object.keys(positions);
@@ -290,20 +295,7 @@ class PhysicsEngine {
    */
   startSimulation() {
     if (this.physicsEnabled === true && this.options.enabled === true) {
-      if (this.physicsWorker) {
-        for(let i = 0; i < this.draggingNodes.length; i++) {
-          let nodeId = this.draggingNodes[i];
-          let node = this.body.nodes[nodeId];
-          this.physicsWorker.postMessage({
-            type: 'update',
-            data: {
-              id: nodeId,
-              x: node.x,
-              y: node.y
-            }
-          });
-        }
-      }
+      this.updateWorkerPositions();
       this.stabilized = false;
 
       // when visible, adaptivity is disabled.
@@ -577,6 +569,22 @@ class PhysicsEngine {
     }
   }
 
+  updateWorkerPositions() {
+    if (this.physicsWorker) {
+      for(let i = 0; i < this.draggingNodes.length; i++) {
+        let nodeId = this.draggingNodes[i];
+        let node = this.body.nodes[nodeId];
+        this.physicsWorker.postMessage({
+          type: 'update',
+          data: {
+            id: nodeId,
+            x: node.x,
+            y: node.y
+          }
+        });
+      }
+    }
+  }
 
   /**
    * Revert the simulation one step. This is done so after stabilization, every new start of the simulation will also say stabilized.

lib/network/modules/PhysicsWorker.js

@@ -37,6 +37,8 @@ class PhysicsWorker {
         let node = this.body.nodes[msg.data.id];
         node.x = msg.data.x;
         node.y = msg.data.y;
+        this.physicsBody.forces[node.id] = {x: 0, y: 0};
+        this.physicsBody.velocities[node.id] = {x: 0, y: 0};
         break;
       case 'options':
         this.options = msg.data;