Node Graph Editor

A visual node graph editor for Unity, built from scratch using the GraphView API — designed to power event-driven, flow-based gameplay logic through a ScriptableObject architecture.

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Overview

Node Graph Editor (com.cjhawk.graphnodeeditor) is a Unity Editor package that provides a fully functional, extensible visual node graph system. Graphs are stored as ScriptableObject assets, and the editor is powered by Unity's GraphView API.

It supports two execution models out of the box:

• Event-driven execution — nodes fire in response to Unity events (collision, key press, mouse click, etc.)
• Linear sequential execution — nodes execute one after another in a defined flow

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Features

• ✅ Visual Node Graph Editor — drag-and-drop canvas with zoom, pan, and grid background
• ✅ ScriptableObject-Based Graphs — graphs persist as Unity assets (GraphAssetSO)
• ✅ Search Window — quickly add nodes by name via a searchable popup
• ✅ Node Inspector — inspect and edit node properties in a dedicated panel when a node is selected
• ✅ Copy / Paste — duplicate nodes with Ctrl/Cmd+C and Ctrl/Cmd+V, with offset positioning
• ✅ Undo / Redo — full Unity Undo integration for all graph mutations
• ✅ Delete — remove selected nodes and their connections via Delete key or context menu
• ✅ Frame All — press F to fit all nodes in view
• ✅ Parallel Execution — ParallelNode with configurable output count for branching logic
• ✅ Custom Node Attributes — annotate fields with [ExposedProperty], [NodeInfo], [DisplayName], and more
• ✅ Event Nodes — built-in nodes for OnEnable, OnFrameUpdate, OnKeyPress, OnMouseClick, OnCollisionEnter, OnTriggerEnter
• ✅ Action Nodes — built-in nodes for Move, Rotate, WaitForSeconds, Timer, DebugLog
• ✅ Scene Object Support — reference in-scene GameObjects from graph assets via SceneObject

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Requirements

Requirement	Version
Unity	2022.3.21f1 or later
Render Pipeline	Any (URP, HDRP, Built-in)

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Installation

Via Unity Package Manager (Git URL)

1. Open Unity → Window → Package Manager
2. Click the + button → Add package from git URL
3. Enter:

   https://github.com/Selva1910/NodeGraphEditor.git
   

Manual Installation

1. Clone or download this repository
2. Copy the package folder into your project's Packages/ directory
3. Unity will automatically detect and import it

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Getting Started

1. Create a Graph Asset

In the Project window, right-click and navigate to:

NodeGraph → Asset

This creates a new GraphAssetSO file in your project.

2. Open the Graph Editor

Double-click any GraphAssetSO asset to open the Node Graph Editor window.

3. Add Nodes

• Right-click on the canvas or press Space to open the node search window
• Select a node type to add it to the graph

4. Connect Nodes

• Drag from an Out port to an In port on another node to create a connection
• Connections only form between compatible port types

5. Run the Graph at Runtime

Attach an EventGraphViewController or LinearGraphViewController component to a GameObject and assign your GraphAssetSO to drive runtime execution.

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Architecture

NodeGraphEditor/
├── Editor/                         # Unity Editor-only code
│   ├── BaseGraphView.cs            # Core GraphView canvas (zoom, pan, CRUD, clipboard)
│   ├── GraphNodeEditor.cs          # Visual node element with port rendering
│   ├── GraphEditorWindow.cs        # EditorWindow host for the graph canvas
│   ├── GraphAssetEditor.cs         # Custom Inspector for GraphAssetSO
│   ├── GraphWindowSearchProvider.cs# Searchable node creation popup
│   ├── NodeInspector.cs            # Per-node property inspector panel
│   ├── MenuManager.cs              # Editor menu items
│   ├── PortTypes.cs                # Port type definitions
│   ├── SceneObjectPickerDrawer.cs  # Custom property drawer for SceneObject
│   ├── SceneObjectPropertyDrawer.cs
│   ├── Resources/                  # Editor resources (icons, USS styles)
│   └── USS/                        # Unity Style Sheets for graph theming
│
└── Runtime/                        # Runtime execution code
    ├── GraphAssetSO.cs             # ScriptableObject graph data model
    ├── BaseGraphNode.cs            # Base class for all nodes
    ├── GraphConnection.cs          # Port connection data model
    ├── INode.cs                    # Node interface
    ├── INodeLifeCycle.cs           # Lifecycle hooks (OnNodeEnter, OnNodeExit)
    ├── EventGraphViewController.cs # Event-driven graph execution controller
    ├── LinearGraphViewController.cs# Sequential graph execution controller
    ├── EventManager.cs             # Central graph event dispatcher
    ├── InputEventManager.cs        # Input event bridging for graphs
    ├── SceneObject.cs              # Serializable in-scene object reference
    ├── SceneObjectManager.cs       # Scene object registration & lookup
    ├── Attributes/                 # Custom C# attributes for node authoring
    │   ├── NodeInfoAttribute.cs    # [NodeInfo] — title, menu path, port config
    │   ├── ExposedPropertyAttribute.cs # [ExposedProperty] — show field in node
    │   ├── ExposedInNodeAttribute.cs   # [ExposedInNode] — render as input port
    │   └── SceneObjectPickerAttribute.cs
    ├── Properties/                 # Serializable property wrapper types
    └── Types/                      # Built-in node implementations
        ├── EntryNode.cs
        ├── ParallelNode.cs
        ├── TimerNode.cs
        ├── WaitForSecondsNode.cs
        ├── MoveNode.cs
        ├── RotateNode.cs
        ├── DebugLogNode.cs
        ├── OnEnableNode.cs
        ├── OnFrameUpdateNode.cs
        ├── OnKeyPressNode.cs
        ├── OnMouseClickNode.cs
        ├── OnCollisionEnterNode.cs
        └── OnTriggerEnterNode.cs

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Creating Custom Nodes

Extend BaseGraphNode and annotate it with [NodeInfo] to register it in the editor.

using NodeGraph;
using UnityEngine;

[NodeInfo(
    title: "My Custom Node",
    menuItem: "Custom/My Custom Node",
    hasFlowInputs: true,
    hasFlowOutputs: true
)]
public class MyCustomNode : BaseGraphNode, INodeLifeCycle
{
    [ExposedProperty]
    [DisplayName("Message")]
    public string message = "Hello!";

    public void OnNodeEnter()
    {
        Debug.Log(message);
    }

    public void OnNodeExit() { }
}

Attribute	Description
[NodeInfo]	Registers title, search menu path, and flow port configuration
[ExposedProperty]	Exposes a field in the node body and inspector
[DisplayName]	Overrides the display label of a field
[ExposedInNode]	Renders an exposed field as a dedicated input port
[ExposedOutNode]	Renders an exposed field as a dedicated output port
INodeLifeCycle	Provides OnNodeEnter() and OnNodeExit() callbacks

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Keyboard Shortcuts

Shortcut	Action
Space / Right-click	Open node search window
F	Frame all nodes in view
Ctrl/Cmd + C	Copy selected nodes
Ctrl/Cmd + V	Paste copied nodes
Delete	Delete selected nodes and connections

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Acknowledgements

This project was inspired by and built upon concepts from the following YouTube live series:

🎬 Building A Node Editor Tool In Unity — Graph View (Live Session)

A huge thanks to the author of this live session for a clear, in-depth walkthrough of Unity's GraphView API. This series laid the conceptual foundation for the node graph architecture used in this package.

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License

This project is licensed under the GNU Affero General Public License v3.0 (AGPL-3.0) — see the LICENSE file for details.

Key implications of AGPL-3.0:

• You may use, modify, and distribute this software freely
• Any modified version must also be released under AGPL-3.0
• If you run a modified version over a network, you must make the source code available to users

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Author

Selvaraj Balakrishnan

• 📧 bselva1910@gmail.com
• 🌐 selva1910.github.io
• 🐙 github.com/Selva1910