Fix drawing triangles in DAG

Editor/ClusterView.cs

@@ -233,7 +233,7 @@ namespace NanoBrain.Unity {
                 Dag.Node to = dag.nodes.FirstOrDefault(x => x.id == e.toId);
                 if (from == null || to == null)
                     continue;
-
+                
                 Vector2 fromPosition = from.position;
                 Vector2 toPosition = to.position;
                 DrawEdge(fromPosition, toPosition);

Editor/Dag.cs

@@ -43,6 +43,144 @@ namespace NanoBrain.Unity {
         public static Node GetNodeById(Dag dag, int id) => dag.nodes.FirstOrDefault(x => x.id == id);
 
         public static void ComputeLayout(Dag dag) {
+            BuildAdjacencyAndPredecessors(dag, out Dictionary<int, List<int>> adjacency, out Dictionary<int, List<int>> predecessors);
+            List<int> order = TopologicalOrder(adjacency, dag.nodes.Select(n => n.id));
+            Dictionary<int, int> column = ComputeLongestPathColumns(adjacency, order, dag.nodes.Select(n => n.id));
+
+            CreateDummiesAndEdges(dag, column, out List<Node> allNodes, out Dictionary<int, int> allColumns, out List<Edge> newEdges);
+
+            List<List<int>> columns = GroupColumns(allColumns);
+            PlaceNodes(allNodes, columns);
+
+            // update dag with new lists (dummies included)
+            dag.edges = newEdges;
+            dag.nodes = allNodes;
+        }
+
+        // Helper: build adjacency and predecessor lists
+        private static void BuildAdjacencyAndPredecessors(Dag dag, out Dictionary<int, List<int>> adjacency, out Dictionary<int, List<int>> predecessors) {
+            adjacency = dag.nodes.ToDictionary(n => n.id, n => new List<int>());
+            predecessors = dag.nodes.ToDictionary(n => n.id, n => new List<int>());
+            foreach (Edge edge in dag.edges) {
+                if (!adjacency.ContainsKey(edge.fromId) || !adjacency.ContainsKey(edge.toId))
+                    continue;
+                adjacency[edge.fromId].Add(edge.toId);
+                predecessors[edge.toId].Add(edge.fromId);
+            }
+        }
+
+        // Helper: compute topological order (returns empty list if cycle present)
+        private static List<int> TopologicalOrder(Dictionary<int, List<int>> adjacency, IEnumerable<int> nodeIds) {
+            Dictionary<int, int> inDegree = nodeIds.ToDictionary(id => id, _ => 0);
+            foreach (KeyValuePair<int, List<int>> keyValue in adjacency)
+                foreach (int to in keyValue.Value) if (inDegree.ContainsKey(to))
+                    inDegree[to]++;
+
+            Queue<int> queue = new(inDegree.Where(keyValue => keyValue.Value == 0).Select(kv => kv.Key));
+            List<int> topo = new();
+            while (queue.Count > 0) {
+                int nodeId = queue.Dequeue();
+                topo.Add(nodeId);
+                foreach (int adjacentNodeId in adjacency[nodeId]) {
+                    if (!inDegree.ContainsKey(adjacentNodeId))
+                        continue;
+                    inDegree[adjacentNodeId]--;
+                    if (inDegree[adjacentNodeId] == 0)
+                        queue.Enqueue(adjacentNodeId);
+                }
+            }
+            return topo;
+        }
+
+        // Helper: longest-path-from-sinks column assignment (deterministic)
+        private static Dictionary<int, int> ComputeLongestPathColumns(Dictionary<int, List<int>> adjacency, List<int> order, IEnumerable<int> nodeIds) {
+            Dictionary<int, int> column = nodeIds.ToDictionary(id => id, _ => 0);
+            foreach (int nodeId in Enumerable.Reverse(order)) {
+                foreach (int child in adjacency[nodeId]) {
+                    int cand = column[child] + 1;
+                    if (cand > column[nodeId])
+                        column[nodeId] = cand;
+                }
+            }
+            return column;
+        }
+
+        // Helper: replace long edges with dummy node chains and return augmented node/column/edge lists
+        private static void CreateDummiesAndEdges(Dag dag, Dictionary<int, int> column, out List<Node> allNodes, out Dictionary<int, int> allColumns, out List<Edge> newEdges) {
+            allColumns = new Dictionary<int, int>(column);
+            allNodes = new List<Node>(dag.nodes);
+            newEdges = new List<Edge>();
+            int nextDummyId = -1;
+
+            foreach (Edge edge in dag.edges) {
+                if (!column.ContainsKey(edge.fromId) || !column.ContainsKey(edge.toId)) {
+                    newEdges.Add(edge);
+                    continue;
+                }
+
+                int columnFrom = column[edge.fromId];
+                int columnTo = column[edge.toId];
+                int span = Mathf.Abs(columnTo - columnFrom);
+                if (span <= 1) {
+                    newEdges.Add(edge);
+                    continue;
+                }
+
+                int prev = edge.fromId;
+                int direction = columnTo > columnFrom ? 1 : -1;
+                for (int step = 1; step < span; step++) {
+                    int dummyCol = columnFrom + step * direction;
+                    int dummyId = nextDummyId--;
+                    Node dummy = new() {
+                        id = dummyId,
+                        position = Vector2.zero
+                    };
+                    // System.Reflection.FieldInfo field = typeof(Node).GetField("isDummy");
+                    // if (field != null) field.SetValue(dummy, true);
+                    allNodes.Add(dummy);
+                    allColumns[dummyId] = dummyCol;
+
+                    Edge newDummyEdge = new() {
+                        fromId = prev,
+                        toId = dummyId
+                    };
+                    newEdges.Add(newDummyEdge);
+                    prev = dummyId;
+                }
+                Edge newEdge = new() {
+                    fromId = prev,
+                    toId = edge.toId
+                };
+                newEdges.Add(newEdge);
+            }
+        }
+
+        // Helper: group columns into ordered list of lists
+        private static List<List<int>> GroupColumns(Dictionary<int, int> allColumns) {
+            return allColumns.GroupBy(kv => kv.Value).OrderBy(g => g.Key).Select(g => g.Select(x => x.Key).ToList()).ToList();
+        }
+
+        // Helper: place nodes vertically within each column
+        private static void PlaceNodes(List<Node> allNodes, List<List<int>> columns) {
+            float hSpacing = 100f;
+            float totalHeight = 400f;
+            for (int columnIx = 0; columnIx < columns.Count; columnIx++) {
+                List<int> nodeList = columns[columnIx];
+                float spacing = totalHeight / Mathf.Max(1, nodeList.Count);
+                float margin = 10 + spacing / 2;
+                for (int i = 0; i < nodeList.Count; i++) {
+                    int id = nodeList[i];
+                    Node node = allNodes.FirstOrDefault(n => n.id == id);
+                    if (node == null)
+                        continue;
+                    float x = (hSpacing * 1.5f) + columnIx * hSpacing;
+                    float y = margin + i * spacing;
+                    node.position = new Vector2(x, y);
+                }
+            }
+        }
+
+        public static void ComputeLayoutKahn(Dag dag) {
             Dictionary<int, List<int>> adjacency = dag.nodes.ToDictionary(n => n.id, n => new List<int>());
             Dictionary<int, int> outdegree = dag.nodes.ToDictionary(node => node.id, n => 0);
             foreach (Edge edge in dag.edges) {
@@ -99,29 +237,6 @@ namespace NanoBrain.Unity {
                 Select(g => g.Select(x => x.Key).ToList()).
                 ToList();
 
-            // Same code without using Linq
-            // Build layers dictionary: layerIndex -> List<int> nodeIds
-            // Dictionary<int, List<int>> layersDict = new();
-            // foreach (KeyValuePair<int, int> kv in layer) {
-            //     int nodeId = kv.Key;
-            //     int layerIndex = kv.Value;
-            //     if (!layersDict.TryGetValue(layerIndex, out List<int> list)) {
-            //         list = new List<int>();
-            //         layersDict[layerIndex] = list;
-            //     }
-            //     list.Add(nodeId);
-            // }
-
-            // // Determine sorted layer indices
-            // List<int> layerIndices = new(layersDict.Keys);
-            // layerIndices.Sort(); // ascending order
-
-            // // Build final List<List<int>> in sorted order
-            // List<List<int>> layers = new();
-            // foreach (int idx in layerIndices) {
-            //     layers.Add(layersDict[idx]);
-            // }
-
             float hSpacing = 100f;
             float totalHeight = 400f;
 
@@ -136,14 +251,11 @@ namespace NanoBrain.Unity {
                     if (node == null)
                         continue;
                     float x = (hSpacing * 1.5f) + columnIx * hSpacing;
-                    //float y = 400 - totalHeight / 2f + i * vSpacing;
                     float y = margin + i * spacing;
-                    // Debug.Log($"({li}, {i}) -> {x}, {y}");
                     node.position = new Vector2(x, y);
                 }
             }
 
-            //Repaint();
         }
     }
 }