Broken, but checkpoint editor/graph/layout split

LayoutNode.js

@@ -0,0 +1,67 @@
+class LayoutNode {
+  constructor(graphNode, nodesByPos, pos) {
+    this.graphNode_ = graphNode;
+    this.nodesByPos_ = nodesByPos;
+    this.pos = pos;
+
+    this.nodesByPos_.set(this.pos.toString(), this);
+  }
+
+  resolveAffinity(nodesByGraphNode) {
+    this.affinity_ = [];
+    for (let aff of this.graphNode_.affinity) {
+      this.affinity_.push({
+        node: nodesByGraphNode.get(aff.node),
+        distanceToWeight: aff.distanceToWeight,
+      });
+    }
+  }
+
+  setTension() {
+    this.vec = [0, 0];
+    this.tension = 0;
+    for (let aff of this.affinity_) {
+      let vec = [], vecsum = 0;
+      for (let i of [0, 1]) {
+        vec[i] = aff.node.pos[i] - this.pos[i];
+        vecsum += Math.abs(vec[i]);
+      };
+      let distance = Math.sqrt(Math.pow(vec[0], 2) + Math.pow(vec[1], 2));
+      let weight = aff.distanceToWeight(distance);
+      for (let i of [0, 1]) {
+        this.vec[i] += (weight * vec[i]) / vecsum;
+      }
+      this.tension += Math.abs(weight);
+    }
+  }
+
+  offsetToPos(offset) {
+    return [
+        this.pos[0] + offset[0],
+        this.pos[1] + offset[1],
+    ];
+  }
+
+  offsetCollides(offset) {
+    let newPos = this.offsetToPos(offset);
+    return this.nodesByPos_.get(newPos.toString());
+  }
+
+  moveTo(pos) {
+    this.nodesByPos_.delete(this.pos.toString());
+    this.pos = pos;
+    this.nodesByPos_.set(this.pos.toString(), this);
+  }
+
+  moveBy(offset) {
+    this.moveTo(this.offsetToPos(offset));
+  }
+
+  savePos() {
+    this.savedPos_ = this.pos;
+  }
+
+  restorePos() {
+    this.moveTo(this.savedPos_);
+  }
+}