Broken, but checkpoint editor/graph/layout split

LayoutGroup.js

@@ -0,0 +1,53 @@
+class LayoutGroup {
+  constructor(nodes) {
+    this.nodes = new Set(nodes);
+    this.tension = 0;
+  }
+
+  setTension() {
+    // Groups don't track tension, since we always want to sort last for total
+    // tension
+    this.vec = [0, 0];
+    for (let node of this.nodes.values()) {
+      node.setTension();
+      for (let i of [0, 1]) {
+        this.vec[i] += node.vec[i];
+      };
+    }
+  }
+
+  offsetCollides(offset) {
+    for (let node of this.nodes.values()) {
+      let other = node.offsetCollides(offset);
+      if (other && !this.nodes.has(other)) {
+        return other;
+      }
+    }
+    return null;
+  }
+
+  savePos() {
+    for (let node of this.nodes.values()) {
+      node.savePos();
+    }
+  }
+
+  restorePos() {
+    for (let node of this.nodes.values()) {
+      node.restorePos();
+    }
+  }
+
+  moveBy(offset) {
+    let nodes = new Set(this.nodes.values());
+    while (nodes.size) {
+      for (let node of nodes) {
+        if (node.offsetCollides(offset)) {
+          continue;
+        }
+        node.moveBy(offset);
+        nodes.delete(node);
+      }
+    }
+  }
+}