Added Microsoft's open source graph layout engine

AssetDependencyGraph/AssetDependencyGraph-Editor.asmdef

@@ -1,14 +1,17 @@
 {
     "name": "AssetDependencyGraph-Editor",
     "references": [],
-    "optionalUnityReferences": [],
     "includePlatforms": [
         "Editor"
     ],
     "excludePlatforms": [],
     "allowUnsafeCode": false,
-    "overrideReferences": false,
-    "precompiledReferences": [],
-    "autoReferenced": true,
-    "defineConstraints": []
+    "overrideReferences": true,
+    "precompiledReferences": [
+        "AutomaticGraphLayout.dll"
+    ],
+    "autoReferenced": false,
+    "defineConstraints": [],
+    "versionDefines": [],
+    "noEngineReferences": false
 }

AssetDependencyGraph/Editor/AssetDependencyGraph.cs

@@ -3,6 +3,7 @@
 #if UNITY_2019_1_OR_NEWER
 using UnityEditor.Experimental.GraphView;
 using UnityEngine.UIElements;
+using UnityEditor.UIElements;
 #else
 using UnityEditor.Experimental.UIElements.GraphView;
 using UnityEngine.Experimental.UIElements;
@@ -40,6 +41,7 @@ public class AssetDependencyGraph : EditorWindow
     private const float kNodeWidth = 250.0f;
 
     private GraphView m_GraphView;
+    private bool m_UseAutoLayout = true;
 
     private readonly List<GraphElement>        m_AssetElements  = new List<GraphElement>();
     private readonly Dictionary<string, Node>  m_GUIDNodeLookup = new Dictionary<string, Node>();
@@ -88,6 +90,13 @@ public void OnEnable()
             text = "Clear"
         });
 
+        var toggle = new ToolbarToggle() {
+            text = "Auto Layout",
+            value = m_UseAutoLayout
+        };
+        toggle.RegisterValueChangedCallback(x => { m_UseAutoLayout = x.newValue; });
+        toolbar.Add(toggle);
+
 #if !UNITY_2019_1_OR_NEWER
         rootVisualElement = this.GetRootVisualContainer();
 #endif
@@ -330,8 +339,10 @@ private void ClearGraph()
         m_GUIDNodeLookup.Clear();
     }
 
-    private void UpdateDependencyNodePlacement(GeometryChangedEvent e)
-    {
+    private void UpdateDependencyNodePlacement(GeometryChangedEvent e) {
+        var element = e.target as VisualElement;
+        element.UnregisterCallback<GeometryChangedEvent>(UpdateDependencyNodePlacement);
+
         // The current y offset in per depth
         var depthYOffset  = new Dictionary<int, float>();
 
@@ -364,5 +375,20 @@ private void UpdateDependencyNodePlacement(GeometryChangedEvent e)
         }
 
         m_DependenciesForPlacement.Clear();
+
+        if(m_UseAutoLayout) {
+            // run graph improvements on top
+            var layouter = new GraphViewLayouter();
+            layouter.Adjust(m_GraphView);
+        }
+
+        element.RegisterCallback<GeometryChangedEvent>(FrameOnce);
+    }
+
+    private void FrameOnce(GeometryChangedEvent e) {
+        if (e.target is VisualElement element)
+            element.UnregisterCallback<GeometryChangedEvent>(FrameOnce);
+
+        m_GraphView.FrameAll();
     }
 }

AssetDependencyGraph/Editor/GraphViewLayouter.cs

@@ -0,0 +1,58 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using UnityEngine;
+using Microsoft.Msagl.Core.Geometry;
+using Microsoft.Msagl.Core.Geometry.Curves;
+using Microsoft.Msagl.Core.Layout;
+using Microsoft.Msagl.Core.Routing;
+using Microsoft.Msagl.Layout.Layered;
+
+public class GraphViewLayouter
+{
+    // https://www.microsoft.com/en-us/research/project/microsoft-automatic-graph-layout/#code-samples
+    public void Adjust(UnityEditor.Experimental.GraphView.GraphView graphView)
+    {
+        var elements = graphView.graphElements.ToList();
+        var nodes = elements.Where(x => x is UnityEditor.Experimental.GraphView.Node)
+            .Cast<UnityEditor.Experimental.GraphView.Node>();
+        var edges = elements.Where(x => x is UnityEditor.Experimental.GraphView.Edge)
+            .Cast<UnityEditor.Experimental.GraphView.Edge>();
+
+        GeometryGraph graph = new GeometryGraph();
+
+        Dictionary<UnityEditor.Experimental.GraphView.Node, Node> geomNodes =
+            new Dictionary<UnityEditor.Experimental.GraphView.Node, Node>();
+
+        foreach (var node in nodes) {
+            var nodeRect = node.GetPosition();
+            Node geometryNode = new Node(CurveFactory.CreateRectangle(nodeRect.width, nodeRect.height, new Point()), node);
+            graph.Nodes.Add(geometryNode);
+            geomNodes.Add(node, geometryNode);
+        }
+
+        foreach (var e in edges) {
+            // Exact edge end positions could be found with e.output.GetGlobalCenter()
+            Edge geometryEdge = new Edge(geomNodes[e.output.node], geomNodes[e.input.node]);
+            graph.Edges.Add(geometryEdge);
+        }
+
+        // settings found to look good (enough separation, not too much, clean layout) by experimentation
+        var settings = new SugiyamaLayoutSettings {
+            Transformation = PlaneTransformation.Rotation(Math.PI / 2),
+            EdgeRoutingSettings = {EdgeRoutingMode = EdgeRoutingMode.StraightLine},
+            // AspectRatio = 9.0 / 16.0, // allows adjusting aspect
+            LayerSeparation = 200,
+            GridSizeByX = 300,
+            GridSizeByY = 300,
+            SnapToGridByY = SnapToGridByY.Bottom
+        };
+        var layout = new LayeredLayout(graph, settings);
+        layout.Run();
+
+        foreach (var n in graph.Nodes) {
+            var unityNode = (UnityEditor.Experimental.GraphView.Node) n.UserData;
+            unityNode.SetPosition(new Rect((float) n.Center.X, (float) n.Center.Y, 0, 0));
+        }
+    }
+}