diff --git a/src/App.vue b/src/App.vue
index 829b1c8..6d51322 100644
--- a/src/App.vue
+++ b/src/App.vue
@@ -16,6 +16,20 @@
         label="Edge opacity"
         hide-details
       ></v-slider>
+      <v-slider
+        v-model="nodeOpacity"
+        :min="0.01" :max="1.00" :step="0.01"
+        thumb-label
+        label="Node opacity"
+        hide-details
+      ></v-slider>
+      <v-slider
+        v-model="nodeStrokeWidth"
+        :min="0" :max="1.00" :step="0.01"
+        thumb-label
+        label="Node stroke width"
+        hide-details
+      ></v-slider>
       <v-slider
         v-model="size"
         :min="0.01" :max="1" :step="0.01"
@@ -34,7 +48,6 @@
         v-model="alpha"
         :min="0.00" :max="1.00" :step="0.01"
         thumb-label
-        :readonly="this.layoutRunning"
         label="Energy"
         hide-details
       ></v-slider>
@@ -110,6 +123,13 @@
         label="Radial field"
         hide-details
       ></v-combobox>
+      <v-slider
+        v-model="gravityStrength"
+        :min="0.00" :max="0.1" :step="0.001"
+        thumb-label
+        label="Gravity"
+        hide-details
+      ></v-slider>
       <v-btn block @click="download()">Download JSON</v-btn>
       <a ref="downloadAnchor" style="display:none"></a>
     </v-navigation-drawer>
@@ -139,11 +159,12 @@ export default {
       fields: [],
       showEdges: false,
       edgeOpacity: 0.5,
+      nodeOpacity: 0.5,
+      nodeStrokeWidth: 1.0,
       size: 0.5,
       sizeField: 'degree',
       layoutRunning: false,
       alpha: 1.0,
-      alphaFromWorker: false,
       chargeStrength: 30,
       theta: 1.5,
       collideStrength: 0.7,
@@ -155,6 +176,7 @@ export default {
       yStrength: 0,
       radialField: null,
       radialStrength: 0,
+      gravityStrength: 0,
       nodeCount: 0,
       edgeCount: 0,
     };
@@ -240,7 +262,6 @@ export default {
         graph.nodes.forEach((n, i) => nodeMap[n.id] = i);
         lines = layer.createFeature('line').data(graph.edges.map(e => [nodeMap[e.source], nodeMap[e.target]])).style({
           position: nodeid => graph.nodes[nodeid],
-          width: 1,
           strokeColor: 'black',
           strokeOpacity: this.edgeOpacity,
         });
@@ -259,13 +280,18 @@ export default {
           }
         });
 
+        // TODO: call geoUtils.convertColor
+        // TODO: look into https://opengeoscience.github.io/geojs/examples/animation/
+        // pointFeature.updateStyleFromArray(updateStyles, null, true);
+
         points = layer.createFeature('point', {
           primitiveShape: 'triangle',
           style: {
             strokeColor: 'black',
             fillColor: nodeid => graph.nodes[nodeid].select ? ['yellow', 'red'][graph.nodes[nodeid].select - 1] : 'grey',
-            fillOpacity: 0.5,
-            strokeOpacity: 0.5,
+            fillOpacity: this.nodeOpacity,
+            strokeOpacity: this.nodeOpacity,
+            strokeWidth: this.nodeStrokeWidth,
           },
           position: nodeid => graph.nodes[nodeid]
         }).data(Object.keys(graph.nodes));
@@ -312,11 +338,6 @@ export default {
         points.position(nodeid => positions[nodeid]);
         map.draw();
       }
-      else if (e.data.type === 'alpha') {
-        this.alphaFromWorker = true;
-        this.alpha = e.data.value;
-        this.$nextTick(() => this.alphaFromWorker = false);
-      }
     }
 
     // Add watchers which sync data to layout worker
@@ -332,6 +353,7 @@ export default {
       'yStrength',
       'radialField',
       'radialStrength',
+      'gravityStrength',
     ].forEach(name => {
       function sendToWorker(value) {
         layoutWorker.postMessage({type: name, value});
@@ -359,11 +381,24 @@ export default {
         map.draw();
       }
     },
+    nodeOpacity(value) {
+      if (points) {
+        points.style('strokeOpacity', value);
+        points.style('fillOpacity', value);
+        points.modified();
+        map.draw();
+      }
+    },
+    nodeStrokeWidth(value) {
+      if (points) {
+        points.style('strokeWidth', value);
+        points.modified();
+        map.draw();
+      }
+    },
     alpha: {
       handler(value) {
-        if (!this.alphaFromWorker) {
-          layoutWorker.postMessage({type: 'alpha', value: value});
-        }
+        layoutWorker.postMessage({type: 'alpha', value: value});
       },
       immediate: true,
     },
@@ -397,7 +432,7 @@ export default {
         reader.onload = function (evt) {
           const extension = file.name.split('.').slice(-1)[0];
           if (extension === 'json') {
-            layoutWorker.postMessage({type: 'loadJSON', text: evt.target.result});
+            layoutWorker.postMessage({type: 'loadJSON', text: JSON.parse(evt.target.result)});
           } else if (extension === 'csv') {
             layoutWorker.postMessage({type: 'loadEdgeList', text: evt.target.result});
           } else {
diff --git a/src/scales.js b/src/scales.js
index f01bd1e..9602f81 100644
--- a/src/scales.js
+++ b/src/scales.js
@@ -21,6 +21,6 @@ export function generateSizeScale(arr, field, size) {
   if (field === 'None') {
     return () => 250 * size;
   }
-  const sizeScale = generateScale(arr, field, {min: 3, max: 500*500, invalid: 2});
+  const sizeScale = generateScale(arr, field, {min: 10*10, max: 500*500, invalid: 2});
   return d => Math.sqrt(sizeScale(d)) * size;
 }
diff --git a/src/worker.js b/src/worker.js
index a19ef5e..b76ce7b 100644
--- a/src/worker.js
+++ b/src/worker.js
@@ -12,10 +12,14 @@ let linkStrengthFunctions = {
   inverseMinDegree: link => linkStrength / Math.min(link.source.degree, link.target.degree),
   inverseSumDegree: link => linkStrength / (link.source.degree + link.target.degree),
   inverseSumSqrtDegree: link => linkStrength / (Math.sqrt(link.source.degree) + Math.sqrt(link.target.degree)),
+  constant: () => linkStrength,
+  radius: link => linkStrength*linkStrength / Math.min(collide.radius()(link.source), collide.radius()(link.target)),
 };
 
 let linkDistanceFunctions = {
   sumSqrtDegree: link => (Math.sqrt(link.source.degree) + Math.sqrt(link.target.degree)) * size,
+  constant: () => size / 20,
+  radius: link => (2 - linkStrength) * (collide.radius()(link.source) + collide.radius()(link.target)),
 };
 
 let link = d3.forceLink().id(d => d.id).distance(linkDistanceFunctions.sumSqrtDegree).strength(linkStrengthFunctions.inverseMinDegree);
@@ -25,33 +29,38 @@ let center = d3.forceCenter();
 let x = d3.forceX();
 let y = d3.forceY();
 let radial = d3.forceRadial();
+let gravity = d3.forceRadial().radius(0);
 let simulation = d3.forceSimulation()
   .alphaMin(0)
   .alphaTarget(0)
+  .alphaDecay(0)
   .stop();
 
 loadGraph = function(graph) {
   function tick() {
-    postMessage({type: 'alpha', value: simulation.alpha()});
     postMessage({type: 'positions', nodes: graph.nodes.map(n => ({x: n.x, y: n.y}))});
   }
 
   if (!graph.nodes) {
     graph.nodes = d3.set([...graph.edges.map(d => d.source), ...graph.edges.map(d => d.target)]).values().map(d => ({
       id: d,
-      degree: 0,
-      x: Math.random()*1000,
-      y: Math.random()*1000,
     }));
   }
   const nodeMap = {};
   graph.nodes.forEach(d => {
+    d.degree = 0;
+    d.id = '' + d.id;
     nodeMap[d.id] = d;
   });
+  graph.edges.forEach(d => {
+    d.source = '' + d.source;
+    d.target = '' + d.target;
+  });
   graph.edges = graph.edges.filter(e => nodeMap[e.source] && nodeMap[e.target]);
   graph.edges.forEach(d => {
-    nodeMap[d.source].degree += 1;
-    nodeMap[d.target].degree += 1;
+    const weight = d.weight !== undefined ? +d.weight : 1
+    nodeMap[d.source].degree += weight;
+    nodeMap[d.target].degree += weight;
   });
 
   graph.nodes.sort((a, b) => d3.ascending(a.degree, b.degree));
@@ -88,7 +97,7 @@ onmessage = function(e) {
     loadGraph({edges: d3.csvParse(e.data.text)});
   }
   else if (e.data.type === 'loadJSON') {
-    loadGraph(JSON.parse(e.data.text));
+    loadGraph(e.data.text);
   }
   else if (e.data.type === 'theta') {
     charge.theta(e.data.value);
@@ -98,16 +107,20 @@ onmessage = function(e) {
   }
   else if (e.data.type === 'size') {
     size = e.data.value;
-    link.strength(link.strength());
     collide.radius(scales.generateSizeScale(simulation.nodes(), sizeField, size));
+    link.distance(link.distance());
+    link.strength(link.strength());
   }
   else if (e.data.type === 'sizeField') {
     sizeField = e.data.value;
     collide.radius(scales.generateSizeScale(simulation.nodes(), sizeField, size));
+    link.distance(link.distance());
+    link.strength(link.strength());
   }
   else if (e.data.type === 'linkStrength') {
     simulation.force('link', e.data.value ? link : null);
     linkStrength = e.data.value;
+    link.distance(link.distance());
     link.strength(link.strength());
   }
   else if (e.data.type === 'chargeStrength') {
@@ -147,6 +160,10 @@ onmessage = function(e) {
       simulation.nodes(), radialField, {area: 1000, min: 0.5, max: 1.5, invalid: 1.6},
     ));
   }
+  else if (e.data.type === 'gravityStrength') {
+    simulation.force('gravity', e.data.value ? gravity : null);
+    gravity.strength(e.data.value);
+  }
   else {
     throw Error(`Unknown message type '${e.data.type}'`);
   }