Added create node form object feature

Author: alelievr

Assets/Examples/DefaultNodes/Nodes/GameObjectNode.cs

@@ -0,0 +1,20 @@
+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+using GraphProcessor;
+using System.Linq;
+
+[System.Serializable, NodeMenuItem("Custom/Game Object")]
+public class GameObjectNode : BaseNode, ICreateNodeFrom<GameObject>
+{
+	[Output(name = "Out"), SerializeField]
+	public GameObject			output;
+
+	public override string		name => "Game Object";
+
+	public bool InitializeNodeFromObject(GameObject value)
+	{
+		output = value;
+		return true;
+	}
+}

Assets/Examples/DefaultNodes/Nodes/GameObjectNode.cs.meta

@@ -8,6 +8,7 @@
 using System.Linq;
 using System;
 using UnityEditor.SceneManagement;
+using System.Reflection;
 
 using Status = UnityEngine.UIElements.DropdownMenuAction.Status;
 using Object = UnityEngine.Object;
@@ -123,6 +124,8 @@ public class BaseGraphView : GraphView, IDisposable
 
 		public SerializedObject		serializedGraph { get; private set; }
 
+		Dictionary<Type, Type> nodeTypePerCreateAssetType = new Dictionary<Type, Type>();
+
 		public BaseGraphView(EditorWindow window)
 		{
 			serializeGraphElements = SerializeGraphElementsCallback;
@@ -588,25 +591,52 @@ void DragPerformedCallback(DragPerformEvent e)
 			var mousePos = (e.currentTarget as VisualElement).ChangeCoordinatesTo(contentViewContainer, e.localMousePosition);
 			var dragData = DragAndDrop.GetGenericData("DragSelection") as List< ISelectable >;
 
-			if (dragData == null)
-				return;
+			// Drag and Drop for elements inside the graph
+			if (dragData != null)
+			{
+				var exposedParameterFieldViews = dragData.OfType<ExposedParameterFieldView>();
+				if (exposedParameterFieldViews.Any())
+				{
+					foreach (var paramFieldView in exposedParameterFieldViews)
+					{
+						RegisterCompleteObjectUndo("Create Parameter Node");
+						var paramNode = BaseNode.CreateFromType< ParameterNode >(mousePos);
+						paramNode.parameterGUID = paramFieldView.parameter.guid;
+						AddNode(paramNode);
+					}
+				}
+			}
 
-			var exposedParameterFieldViews = dragData.OfType<ExposedParameterFieldView>();
-			if (exposedParameterFieldViews.Any())
+			// External objects drag and drop
+			if (DragAndDrop.objectReferences.Length > 0)
 			{
-				foreach (var paramFieldView in exposedParameterFieldViews)
+				RegisterCompleteObjectUndo("Create Node From Object(s)");
+				foreach (var obj in DragAndDrop.objectReferences)
 				{
-					RegisterCompleteObjectUndo("Create Parameter Node");
-					var paramNode = BaseNode.CreateFromType< ParameterNode >(mousePos);
-					paramNode.parameterGUID = paramFieldView.parameter.guid;
-					AddNode(paramNode);
+					var objectType = obj.GetType();
+
+					foreach (var kp in nodeTypePerCreateAssetType)
+					{
+						if (kp.Key.IsAssignableFrom(objectType))
+						{
+							var node = BaseNode.CreateFromType(kp.Value, mousePos);
+							var initializeFunction = kp.Value.GetMethod(nameof(ICreateNodeFrom<Object>.InitializeNodeFromObject), BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);
+							if ((bool)initializeFunction.Invoke(node, new []{obj}))
+							{
+								AddNode(node);
+							}
+							else
+								break;	
+						}
+					}
 				}
 			}
 		}
 
 		void DragUpdatedCallback(DragUpdatedEvent e)
         {
             var dragData = DragAndDrop.GetGenericData("DragSelection") as List<ISelectable>;
+			var dragObjects = DragAndDrop.objectReferences;
             bool dragging = false;
 
             if (dragData != null)
@@ -618,10 +648,11 @@ void DragUpdatedCallback(DragUpdatedEvent e)
 				}
             }
 
+			if (dragObjects.Length > 0)
+				dragging = true;
+
             if (dragging)
-            {
                 DragAndDrop.visualMode = DragAndDropVisualMode.Generic;
-            }
 
 			UpdateNodeInspectorSelection();
         }
@@ -717,6 +748,20 @@ public void Initialize(BaseGraph graph)
 			InitializeView();
 
 			NodeProvider.LoadGraph(graph);
+
+			// Register the nodes that can be created from assets
+			foreach (var nodeInfo in NodeProvider.GetNodeMenuEntries(graph))
+			{
+				var interfaces = nodeInfo.type.GetInterfaces();
+				foreach (var i in interfaces)
+				{
+					if (i.IsGenericType && i.GetGenericTypeDefinition() == typeof(ICreateNodeFrom<>))
+					{
+						var genericArgument = i.GetGenericArguments()[0];
+						nodeTypePerCreateAssetType[genericArgument] = nodeInfo.type;
+					}
+				}
+			}
 		}
 
 		public void ClearGraphElements()
@@ -888,6 +933,13 @@ public BaseNodeView AddNodeView(BaseNode node)
 			return baseNodeView;
 		}
 
+		public void RemoveNode(BaseNode node)
+		{
+			var view = nodeViewsPerNode[node];
+			RemoveNodeView(view);
+			graph.RemoveNode(node);
+		}
+
 		public void RemoveNodeView(BaseNodeView nodeView)
 		{
 			RemoveElement(nodeView);

Assets/com.alelievr.NodeGraphProcessor/Editor/Views/BaseGraphView.cs

@@ -141,8 +141,12 @@ void OnDragUpdatedEvent(DragUpdatedEvent evt)
         {
             DragAndDrop.visualMode = DragAndDropVisualMode.Move;
             int newIndex = GetInsertIndexFromMousePosition(evt.mousePosition);
+            var graphSelectionDragData = DragAndDrop.GetGenericData("DragSelection");
 
-            foreach (var obj in DragAndDrop.GetGenericData("DragSelection") as List<ISelectable>)
+            if (graphSelectionDragData == null)
+                return;
+
+            foreach (var obj in graphSelectionDragData as List<ISelectable>)
             {
                 if (obj is ExposedParameterFieldView view)
                 {

Assets/com.alelievr.NodeGraphProcessor/Editor/Views/ExposedParameterView.cs

@@ -0,0 +1,20 @@
+using UnityEngine;
+using System;
+using Object = UnityEngine.Object;
+
+namespace GraphProcessor
+{
+    /// <summary>
+    /// Implement this interface on a BaseNode, it allows you to automatically spawn a node if an asset of type T is dropped in the graphview area
+    /// </summary>
+    /// <typeparam name="T">The type object your node will be created from, it must be a subclass of UnityEngine.Object</typeparam>
+    public interface ICreateNodeFrom<T> where T : Object
+    {
+        /// <summary>
+        /// This function is called just after creating the node from an object and allows you to initialize the node with the object data.
+        /// </summary>
+        /// <param name="value">Object value</param>
+        /// <returns>True if the initialization happened correctly. False otherwise, returning false will discard your node.</returns>
+        bool InitializeNodeFromObject(T value);
+    }
+}