01 | 易学教程

Unity AssetStore中关于Node节点编辑器相关的插件可是数不胜数，状态机，行为树，Shader 可视化等等。

Unity自己也有 Animator的窗口使用，还有新的Shader Graph。

现在Unity的编辑器代码已经开源了，还没有时间看。

第一部分，创建界面功能
在这篇博文中，我们将在Unity中创建我们自己的基于节点的编辑器。是一个简单的节点编辑器，您可以进行改进。

我们将在这篇文章中创建这个窗口（点击查看gif的动作）

创建窗口
我们先创建一个简单的编辑器窗口。代码的结构与我们在之前的文章中开发的控制台克隆类似：首先绘制元素，然后处理输入，并且如果由于输入事件而改变GUI，则强制窗口重绘。
using UnityEngine;
using UnityEditor;
using System.Collections.Generic;

public class NodeBasedEditor : EditorWindow
{
    [MenuItem("Window/Node Based Editor")]
    private static void OpenWindow()
    {
        NodeBasedEditor window = GetWindow<NodeBasedEditor>();
        window.titleContent = new GUIContent("Node Based Editor");
    }

    private void OnGUI()
    {
        DrawNodes();

        ProcessEvents(Event.current);

        if (GUI.changed) Repaint();
    }

    private void DrawNodes()
    {
    }

    private void ProcessEvents(Event e)
    {
    }
}
绘制节点
那么，因为这是一个节点编辑器，它应该包含一个节点列表，这就要求我们定义一个List<Node>。但首先我们应该定义Node类。节点将负责绘制自己并处理自己的事件。与NodeBasedEditor中的ProcessEvents(Event e) 不同，Node中的ProcessEvents(Event e) 将返回一个布尔值，以便我们检查是否应该重新绘制GUI。

using System;
using UnityEditor;
using UnityEngine;

public class Node
{
    public Rect rect;
    public string title;

    public GUIStyle style;

    public Node(Vector2 position, float width, float height, GUIStyle nodeStyle)
    {
        rect = new Rect(position.x, position.y, width, height);
        style = nodeStyle;
    }

    public void Drag(Vector2 delta)
    {
        rect.position += delta;
    }

    public void Draw()
    {
        GUI.Box(rect, title, style);
    }

    public bool ProcessEvents(Event e)
    {
        return false;
    }
}

using UnityEngine;
using UnityEditor;
using System.Collections.Generic;

public class NodeBasedEditor : EditorWindow
{
    private List<Node> nodes;

    [MenuItem("Window/Node Based Editor")]
    private static void OpenWindow()
    {
        NodeBasedEditor window = GetWindow<NodeBasedEditor>();
        window.titleContent = new GUIContent("Node Based Editor");
    }

    private void OnGUI()
    {
        DrawNodes();

        ProcessEvents(Event.current);

        if (GUI.changed) Repaint();
    }

    private void DrawNodes()
    {
        if (nodes != null)
        {
            for (int i = 0; i < nodes.Count; i++)
            {
                nodes[i].Draw();
            }
        }
    }

    private void ProcessEvents(Event e)
    {
    }
}

创建节点
节点现在在编辑器中绘制，但如果我们不创建节点，则无法看到它们。当用户在编辑器中点击右键时，我们应该显示一个带有“Add node”项的上下文菜单。当用户点击“Add node”时，我们将创建一个节点并将其添加到节点列表中，以便绘制它。节点需要位置，宽度，高度和样式; 位置将是鼠标的当前位置，宽度将是200，高度将是50（是的，我不喜欢在代码中使用magic numbers，但这将是一个简单的编辑器），我们将复制Animator窗口的节点样式进行造型。

using UnityEngine;
using UnityEditor;
using System.Collections.Generic;

public class NodeBasedEditor : EditorWindow
{
    private List<Node> nodes;

    private GUIStyle nodeStyle;

    [MenuItem("Window/Node Based Editor")]
    private static void OpenWindow()
    {
        NodeBasedEditor window = GetWindow<NodeBasedEditor>();
        window.titleContent = new GUIContent("Node Based Editor");
    }

    private void OnEnable()
    {
        nodeStyle = new GUIStyle();
        nodeStyle.normal.background = EditorGUIUtility.Load("builtin skins/darkskin/images/node1.png") as Texture2D;
        nodeStyle.border = new RectOffset(12, 12, 12, 12);
    }

    private void OnGUI()
    {
        DrawNodes();

        ProcessEvents(Event.current);

        if (GUI.changed) Repaint();
    }

    private void DrawNodes()
    {
        if (nodes != null)
        {
            for (int i = 0; i < nodes.Count; i++)
            {
                nodes[i].Draw();
            }
        }
    }

    private void ProcessEvents(Event e)
    {
        switch (e.type)
        {
            case EventType.MouseDown:
                if (e.button == 1)
                {
                    ProcessContextMenu(e.mousePosition);
                }
                break;
        }
    }

    private void ProcessContextMenu(Vector2 mousePosition)
    {
        GenericMenu genericMenu = new GenericMenu();
        genericMenu.AddItem(new GUIContent("Add node"), false, () => OnClickAddNode(mousePosition));
        genericMenu.ShowAsContext();
    }

    private void OnClickAddNode(Vector2 mousePosition)
    {
        if (nodes == null)
        {
            nodes = new List<Node>();
        }

        nodes.Add(new Node(mousePosition, 200, 50, nodeStyle));
    }
}

使节点可拖动
好的，现在我们可以添加节点了，但是我们不能拖动它们。正如我前面提到的，节点将处理它们自己的事件，因此我们将在Node类中处理拖动事件。这里需要注意的一点是，我们应该使用Use() 方法“using”拖动事件。稍后，我们将添加画布拖动，并且我们不希望同时拖动节点和整个画布（“using”一个事件阻止它被其他过程使用，即停止事件冒泡）。另请注意， ProcessNodeEvents(Event e)中的for循环向后遍历节点列表，因为最后一个节点位于顶部，所以它应该首先处理事件。

using System;
using UnityEditor;
using UnityEngine;

public class Node
{
    public Rect rect;
    public string title;
    public bool isDragged;

    public GUIStyle style;

    public Node(Vector2 position, float width, float height, GUIStyle nodeStyle)
    {
        rect = new Rect(position.x, position.y, width, height);
        style = nodeStyle;
    }

    public void Drag(Vector2 delta)
    {
        rect.position += delta;
    }

    public void Draw()
    {
        GUI.Box(rect, title, style);
    }

    public bool ProcessEvents(Event e)
    {
        switch (e.type)
        {
            case EventType.MouseDown:
                if (e.button == 0)
                {
                    if (rect.Contains(e.mousePosition))
                    {
                        isDragged = true;
                        GUI.changed = true;
                    }
                    else
                    {
                        GUI.changed = true;
                    }
                }
                break;

            case EventType.MouseUp:
                isDragged = false;
                break;

            case EventType.MouseDrag:
                if (e.button == 0 && isDragged)
                {
                    Drag(e.delta);
                    e.Use();
                    return true;
                }
                break;
        }

        return false;
    }
}
NodeBaseEditor.cs
    private void OnGUI()
    {
        DrawNodes();

        ProcessNodeEvents(Event.current);
        ProcessEvents(Event.current);

        if (GUI.changed) Repaint();
    }

    private void DrawNodes()
    {
        if (nodes != null)
        {
            for (int i = 0; i < nodes.Count; i++)
            {
                nodes[i].Draw();
            }
        }
    }

    private void ProcessEvents(Event e)
    {
        switch (e.type)
        {
            case EventType.MouseDown:
                if (e.button == 1)
                {
                    ProcessContextMenu(e.mousePosition);
                }
                break;
        }
    }

    private void ProcessNodeEvents(Event e)
    {
        if (nodes != null)
        {
            for (int i = nodes.Count - 1; i >= 0; i--)
            {
                bool guiChanged = nodes[i].ProcessEvents(e);

                if (guiChanged)
                {
                    GUI.changed = true;
                }
            }
        }
    }

    private void ProcessContextMenu(Vector2 mousePosition)
    {
        GenericMenu genericMenu = new GenericMenu();
        genericMenu.AddItem(new GUIContent("Add node"), false, () => OnClickAddNode(mousePosition));
        genericMenu.ShowAsContext();
    }

创建节点之间的连接
我们的节点编辑器现在有节点，但我们也应该能够连接它们。为了做到这一点，我们需要一个节点上的两个连接点（in和out）以及它们之间的连接。一个连接点有一个矩形（以便我们可以绘制它），有一个类型（in或out），有一个样式并引用它的父节点。因此，我们的ConnectionPoint 类将是一个非常简单的类。在特定位置绘制按钮并在点击该按钮时执行操作。

另一方面，连接有两个连接点和一个动作来删除它。 Connection类比ConnectionPoint简单得多，但它引入了一个新概念：Handles。该类实际上用于在场景视图中绘制3D GUI控件，但它是唯一具有贝塞尔绘图方法的类：Handles.DrawBezier(Vector3, Vector3, Vector3, Vector3, Color, Texture2D, float). 。它需要7个参数，前4个参数是位置控制（起始位置，结束位置，起始切线和终止切线），而其余的则决定贝塞尔的外观。（这个就太方便了，不需要引入第三方插件或者自己写了）
ConnectionPoint.cs
using System;
using UnityEngine;

public enum ConnectionPointType { In, Out }

public class ConnectionPoint
{
    public Rect rect;

    public ConnectionPointType type;

    public Node node;

    public GUIStyle style;

    public Action<ConnectionPoint> OnClickConnectionPoint;

    public ConnectionPoint(Node node, ConnectionPointType type, GUIStyle style, Action<ConnectionPoint> OnClickConnectionPoint)
    {
        this.node = node;
        this.type = type;
        this.style = style;
        this.OnClickConnectionPoint = OnClickConnectionPoint;
        rect = new Rect(0, 0, 10f, 20f);
    }

    public void Draw()
    {
        rect.y = node.rect.y + (node.rect.height * 0.5f) - rect.height * 0.5f;

        switch (type)
        {
            case ConnectionPointType.In:
                rect.x = node.rect.x - rect.width + 8f;
                break;

            case ConnectionPointType.Out:
                rect.x = node.rect.x + node.rect.width - 8f;
                break;
        }

        if (GUI.Button(rect, "", style))
        {
            if (OnClickConnectionPoint != null)
            {
                OnClickConnectionPoint(this);
            }
        }
    }
}
Connection.cs
using System;
using UnityEditor;
using UnityEngine;

public class Connection
{
    public ConnectionPoint inPoint;
    public ConnectionPoint outPoint;
    public Action<Connection> OnClickRemoveConnection;

    public Connection(ConnectionPoint inPoint, ConnectionPoint outPoint, Action<Connection> OnClickRemoveConnection)
    {
        this.inPoint = inPoint;
        this.outPoint = outPoint;
        this.OnClickRemoveConnection = OnClickRemoveConnection;
    }

    public void Draw()
    {
        Handles.DrawBezier(
            inPoint.rect.center,
            outPoint.rect.center,
            inPoint.rect.center + Vector2.left * 50f,
            outPoint.rect.center - Vector2.left * 50f,
            Color.white,
            null,
            2f
        );

        if (Handles.Button((inPoint.rect.center + outPoint.rect.center) * 0.5f, Quaternion.identity, 4, 8, Handles.RectangleCap))
        {
            if (OnClickRemoveConnection != null)
            {
                OnClickRemoveConnection(this);
            }
        }
    }
}

绘图连接
由于Connection 和ConnectionPoint类已准备就绪，我们所要做的就是在Node类中绘制连接点并在NodeBasedEditor中绘制连接。 Node类中的更改将最小化; 我们将定义两个连接点，修改构造函数，以便我们可以传递样式和动作，并使用 Draw() 方法绘制它们。

但是，NodeBasedEditor 需要进行重大修改。首先，我们需要为连接点定义样式。你可以为它们两个使用单一的样式，但我希望它们看起来不同，所以我将为每个样式使用不同的样式。我们将在OnEnable() 中初始化这些样式，就像我们初始化节点样式一样。

其次，我们需要跟踪点击的连接点，这样当用户选择一个进出时，我们应该在它们之间建立一个连接。这一步包括大部分增加：

OnClickInPoint(ConnectionPoint) 处理点击入点。
OnClickOutPoint(ConnectionPoint) 处理点击出点。
OnClickRemoveConnection(Connection) 处理单击连接上的删除按钮。
CreateConnection()  在选择入点和出点时创建连接。
ClearConnectionSelection()  清除选定的点。
最后，我们需要在 OnGUI() 中绘制连接，就像我们绘制节点一样。
using System;
using UnityEditor;
using UnityEngine;

public class Node
{
    public Rect rect;
    public string title;
    public bool isDragged;

    public ConnectionPoint inPoint;
    public ConnectionPoint outPoint;

    public GUIStyle style;

    public Node(Vector2 position, float width, float height, GUIStyle nodeStyle, GUIStyle inPointStyle, GUIStyle outPointStyle, Action<ConnectionPoint> OnClickInPoint, Action<ConnectionPoint> OnClickOutPoint)
    {
        rect = new Rect(position.x, position.y, width, height);
        style = nodeStyle;
        inPoint = new ConnectionPoint(this, ConnectionPointType.In, inPointStyle, OnClickInPoint);
        outPoint = new ConnectionPoint(this, ConnectionPointType.Out, outPointStyle, OnClickOutPoint);
    }

    public void Drag(Vector2 delta)
    {
        rect.position += delta;
    }

    public void Draw()
    {
        inPoint.Draw();
        outPoint.Draw();
        GUI.Box(rect, title, style);
    }

    public bool ProcessEvents(Event e)
    {
        switch (e.type)
        {
            case EventType.MouseDown:
                if (e.button == 0)
                {
                    if (rect.Contains(e.mousePosition))
                    {
                        isDragged = true;
                        GUI.changed = true;
                    }
                    else
                    {
                        GUI.changed = true;
                    }
                }
                break;

            case EventType.MouseUp:
                isDragged = false;
                break;

            case EventType.MouseDrag:
                if (e.button == 0 && isDragged)
                {
                    Drag(e.delta);
                    e.Use();
                    return true;
                }
                break;
        }

        return false;
    }
}

using UnityEngine;
using UnityEditor;
using System.Collections.Generic;

public class NodeBasedEditor : EditorWindow
{
    private List<Node> nodes;
    private List<Connection> connections;

    private GUIStyle nodeStyle;
    private GUIStyle inPointStyle;
    private GUIStyle outPointStyle;

    private ConnectionPoint selectedInPoint;
    private ConnectionPoint selectedOutPoint;

    [MenuItem("Window/Node Based Editor")]
    private static void OpenWindow()
    {
        NodeBasedEditor window = GetWindow<NodeBasedEditor>();
        window.titleContent = new GUIContent("Node Based Editor");
    }

    private void OnEnable()
    {
        nodeStyle = new GUIStyle();
        nodeStyle.normal.background = EditorGUIUtility.Load("builtin skins/darkskin/images/node1.png") as Texture2D;
        nodeStyle.border = new RectOffset(12, 12, 12, 12);

        inPointStyle = new GUIStyle();
        inPointStyle.normal.background = EditorGUIUtility.Load("builtin skins/darkskin/images/btn left.png") as Texture2D;
        inPointStyle.active.background = EditorGUIUtility.Load("builtin skins/darkskin/images/btn left on.png") as Texture2D;
        inPointStyle.border = new RectOffset(4, 4, 12, 12);

        outPointStyle = new GUIStyle();
        outPointStyle.normal.background = EditorGUIUtility.Load("builtin skins/darkskin/images/btn right.png") as Texture2D;
        outPointStyle.active.background = EditorGUIUtility.Load("builtin skins/darkskin/images/btn right on.png") as Texture2D;
        outPointStyle.border = new RectOffset(4, 4, 12, 12);
    }

    private void OnGUI()
    {
        DrawNodes();
        DrawConnections();

        ProcessNodeEvents(Event.current);
        ProcessEvents(Event.current);

        if (GUI.changed) Repaint();
    }

    private void DrawNodes()
    {
        if (nodes != null)
        {
            for (int i = 0; i < nodes.Count; i++)
            {
                nodes[i].Draw();
            }
        }
    }

    private void DrawConnections()
    {
        if (connections != null)
        {
            for (int i = 0; i < connections.Count; i++)
            {
                connections[i].Draw();
            }
        }
    }

    private void ProcessEvents(Event e)
    {
        switch (e.type)
        {
            case EventType.MouseDown:
                if (e.button == 0)
                {
                    ClearConnectionSelection();
                }

                if (e.button == 1)
                {
                    ProcessContextMenu(e.mousePosition);
                }
                break;
        }
    }

    private void ProcessNodeEvents(Event e)
    {
        if (nodes != null)
        {
            for (int i = nodes.Count - 1; i >= 0; i--)
            {
                bool guiChanged = nodes[i].ProcessEvents(e);

                if (guiChanged)
                {
                    GUI.changed = true;
                }
            }
        }
    }

    private void ProcessContextMenu(Vector2 mousePosition)
    {
        GenericMenu genericMenu = new GenericMenu();
        genericMenu.AddItem(new GUIContent("Add node"), false, () => OnClickAddNode(mousePosition));
        genericMenu.ShowAsContext();
    }

    private void OnClickAddNode(Vector2 mousePosition)
    {
        if (nodes == null)
        {
            nodes = new List<Node>();
        }

        nodes.Add(new Node(mousePosition, 200, 50, nodeStyle, inPointStyle, outPointStyle, OnClickInPoint, OnClickOutPoint));
    }

    private void OnClickInPoint(ConnectionPoint inPoint)
    {
        selectedInPoint = inPoint;

        if (selectedOutPoint != null)
        {
            if (selectedOutPoint.node != selectedInPoint.node)
            {
                CreateConnection();
                ClearConnectionSelection();
            }
            else
            {
                ClearConnectionSelection();
            }
        }
    }

    private void OnClickOutPoint(ConnectionPoint outPoint)
    {
        selectedOutPoint = outPoint;

        if (selectedInPoint != null)
        {
            if (selectedOutPoint.node != selectedInPoint.node)
            {
                CreateConnection();
                ClearConnectionSelection();
            }
            else
            {
                ClearConnectionSelection();
            }
        }
    }

    private void OnClickRemoveConnection(Connection connection)
    {
        connections.Remove(connection);
    }

    private void CreateConnection()
    {
        if (connections == null)
        {
            connections = new List<Connection>();
        }

        connections.Add(new Connection(selectedInPoint, selectedOutPoint, OnClickRemoveConnection));
    }

    private void ClearConnectionSelection()
    {
        selectedInPoint = null;
        selectedOutPoint = null;
    }
}

选择节点
当用户点击一个节点时，我们应该提供反馈，以便他们知道他们选择了哪个节点（或者是否有节点被选中）。这在用户想要删除节点时很有用。

    private void OnClickAddNode(Vector2 mousePosition)
    {
        if (nodes == null)
        {
            nodes = new List<Node>();
        }

        nodes.Add(new Node(mousePosition, 200, 50, nodeStyle, selectedNodeStyle, inPointStyle, outPointStyle, OnClickInPoint, OnClickOutPoint));
    }

删除节点
一些节点编辑喜欢将节点按钮放在节点本身上，但在我们的情况下，这可能是危险的：用户可能会意外地删除节点。所以，我们要做下一件最好的事情：将该按钮放在上下文菜单上。用户应该首先选择节点，然后右键单击它以访问删除节点按钮。当用户点击删除节点时，我们将从节点列表中删除该节点。但是，该节点可能会连接到其他节点，所以我们应该首先删除这些连接。

using System;
using UnityEditor;
using UnityEngine;

public class Node
{
    public Rect rect;
    public string title;
    public bool isDragged;
    public bool isSelected;

    public ConnectionPoint inPoint;
    public ConnectionPoint outPoint;

    public GUIStyle style;
    public GUIStyle defaultNodeStyle;
    public GUIStyle selectedNodeStyle;

    public Action<Node> OnRemoveNode;

    public Node(Vector2 position, float width, float height, GUIStyle nodeStyle, GUIStyle selectedStyle, GUIStyle inPointStyle, GUIStyle outPointStyle, Action<ConnectionPoint> OnClickInPoint, Action<ConnectionPoint> OnClickOutPoint, Action<Node> OnClickRemoveNode)
    {
        rect = new Rect(position.x, position.y, width, height);
        style = nodeStyle;
        inPoint = new ConnectionPoint(this, ConnectionPointType.In, inPointStyle, OnClickInPoint);
        outPoint = new ConnectionPoint(this, ConnectionPointType.Out, outPointStyle, OnClickOutPoint);
        defaultNodeStyle = nodeStyle;
        selectedNodeStyle = selectedStyle;
        OnRemoveNode = OnClickRemoveNode;
    }

    public void Drag(Vector2 delta)
    {
        rect.position += delta;
    }

    public void Draw()
    {
        inPoint.Draw();
        outPoint.Draw();
        GUI.Box(rect, title, style);
    }

    public bool ProcessEvents(Event e)
    {
        switch (e.type)
        {
            case EventType.MouseDown:
                if (e.button == 0)
                {
                    if (rect.Contains(e.mousePosition))
                    {
                        isDragged = true;
                        GUI.changed = true;
                        isSelected = true;
                        style = selectedNodeStyle;
                    }
                    else
                    {
                        GUI.changed = true;
                        isSelected = false;
                        style = defaultNodeStyle;
                    }
                }

                if (e.button == 1 && isSelected && rect.Contains(e.mousePosition))
                {
                    ProcessContextMenu();
                    e.Use();
                }
                break;

            case EventType.MouseUp:
                isDragged = false;
                break;

            case EventType.MouseDrag:
                if (e.button == 0 && isDragged)
                {
                    Drag(e.delta);
                    e.Use();
                    return true;
                }
                break;
        }

        return false;
    }

    private void ProcessContextMenu()
    {
        GenericMenu genericMenu = new GenericMenu();
        genericMenu.AddItem(new GUIContent("Remove node"), false, OnClickRemoveNode);
        genericMenu.ShowAsContext();
    }

    private void OnClickRemoveNode()
    {
        if (OnRemoveNode != null)
        {
            OnRemoveNode(this);
        }
    }
}
NodeBasedEditor.cs
    private void OnClickAddNode(Vector2 mousePosition)
    {
        if (nodes == null)
        {
            nodes = new List<Node>();
        }

        nodes.Add(new Node(mousePosition, 200, 50, nodeStyle, selectedNodeStyle, inPointStyle, outPointStyle, OnClickInPoint, OnClickOutPoint, OnClickRemoveNode));
    }

    private void OnClickRemoveNode(Node node)
    {
        if (connections != null)
        {
            List<Connection> connectionsToRemove = new List<Connection>();

            for (int i = 0; i < connections.Count; i++)
            {
                if (connections[i].inPoint == node.inPoint || connections[i].outPoint == node.outPoint)
                {
                    connectionsToRemove.Add(connections[i]);
                }
            }

            for (int i = 0; i < connectionsToRemove.Count; i++)
            {
                connections.Remove(connectionsToRemove[i]);
            }

            connectionsToRemove = null;
        }

        nodes.Remove(node);
    }

最后的接触
节点编辑器在这一点上是完整的，但它缺少一些可以提升用户体验的重要功能：

可拖动的画布，
从所选连接点到鼠标位置的贝塞尔曲线，
背景中的网格。
让我们的画布可以拖动是最简单的，所以让我们从这个开始。我们所要做的只是将鼠标拖放到节点列表中的每个节点。

NodeBasedEditor.cs
public class NodeBasedEditor : EditorWindow
{
    private List<Node> nodes;
    private List<Connection> connections;

    private GUIStyle nodeStyle;
    private GUIStyle selectedNodeStyle;
    private GUIStyle inPointStyle;
    private GUIStyle outPointStyle;

    private ConnectionPoint selectedInPoint;
    private ConnectionPoint selectedOutPoint;

    private Vector2 drag;

    ...

    private void ProcessEvents(Event e)
    {
        drag = Vector2.zero;

        switch (e.type)
        {
            case EventType.MouseDown:
                if (e.button == 0)
                {
                    ClearConnectionSelection();
                }

                if (e.button == 1)
                {
                    ProcessContextMenu(e.mousePosition);
                }
            break;

            case EventType.MouseDrag:
                if (e.button == 0)
                {
                    OnDrag(e.delta);
                }
            break;
        }
    }

    private void OnDrag(Vector2 delta)
    {
        drag = delta;

        if (nodes != null)
        {
            for (int i = 0; i < nodes.Count; i++)
            {
                nodes[i].Drag(delta);
            }
        }

        GUI.changed = true;
    }
接下来，从所选连接点绘制贝塞尔到鼠标位置。通过绘制这个贝塞尔曲线，我们将让用户知道选择了哪个连接点以及它们的连接将如何。
NodeBasedEditor.cs
    private void OnGUI()
    {
        DrawNodes();
        DrawConnections();

        DrawConnectionLine(Event.current);

        ProcessNodeEvents(Event.current);
        ProcessEvents(Event.current);

        if (GUI.changed) Repaint();
    }

    private void DrawConnectionLine(Event e)
    {
        if (selectedInPoint != null && selectedOutPoint == null)
        {
            Handles.DrawBezier(
                selectedInPoint.rect.center,
                e.mousePosition,
                selectedInPoint.rect.center + Vector2.left * 50f,
                e.mousePosition - Vector2.left * 50f,
                Color.white,
                null,
                2f
            );

            GUI.changed = true;
        }

        if (selectedOutPoint != null && selectedInPoint == null)
        {
            Handles.DrawBezier(
                selectedOutPoint.rect.center,
                e.mousePosition,
                selectedOutPoint.rect.center - Vector2.left * 50f,
                e.mousePosition + Vector2.left * 50f,
                Color.white,
                null,
                2f
            );

            GUI.changed = true;
        }
    }

最后，绘制网格：
public class NodeBasedEditor : EditorWindow
{
    private List<Node> nodes;
    private List<Connection> connections;

    private GUIStyle nodeStyle;
    private GUIStyle selectedNodeStyle;
    private GUIStyle inPointStyle;
    private GUIStyle outPointStyle;

    private ConnectionPoint selectedInPoint;
    private ConnectionPoint selectedOutPoint;

    private Vector2 offset;
    private Vector2 drag;

    ...

    private void OnGUI()
    {
        DrawGrid(20, 0.2f, Color.gray);
        DrawGrid(100, 0.4f, Color.gray);

        DrawNodes();
        DrawConnections();

        DrawConnectionLine(Event.current);

        ProcessNodeEvents(Event.current);
        ProcessEvents(Event.current);

        if (GUI.changed) Repaint();
    }

    private void DrawGrid(float gridSpacing, float gridOpacity, Color gridColor)
    {
        int widthDivs = Mathf.CeilToInt(position.width / gridSpacing);
        int heightDivs = Mathf.CeilToInt(position.height / gridSpacing);

        Handles.BeginGUI();
        Handles.color = new Color(gridColor.r, gridColor.g, gridColor.b, gridOpacity);

        offset += drag * 0.5f;
        Vector3 newOffset = new Vector3(offset.x % gridSpacing, offset.y % gridSpacing, 0);

        for (int i = 0; i < widthDivs; i++)
        {
            Handles.DrawLine(new Vector3(gridSpacing * i, -gridSpacing, 0) + newOffset, new Vector3(gridSpacing * i, position.height, 0f) + newOffset);
        }

        for (int j = 0; j < heightDivs; j++)
        {
            Handles.DrawLine(new Vector3(-gridSpacing, gridSpacing * j, 0) + newOffset, new Vector3(position.width, gridSpacing * j, 0f) + newOffset);
        }

        Handles.color = Color.white;
        Handles.EndGUI();
    }

结论
结束。您可以开发它并创建自己的自定义节点编辑器。这是我在制作原型时编写的任务编辑器：

和往常一样，下面是完整的脚本。直到下一次。
using UnityEngine;
using UnityEditor;
using System.Collections.Generic;

public class NodeBasedEditor : EditorWindow
{
private List<Node> nodes;
private List<Connection> connections;

private GUIStyle nodeStyle;
private GUIStyle selectedNodeStyle;
private GUIStyle inPointStyle;
private GUIStyle outPointStyle;

private ConnectionPoint selectedInPoint;
private ConnectionPoint selectedOutPoint;

private Vector2 offset;
private Vector2 drag;

[MenuItem("Window/Node Based Editor")]
private static void OpenWindow()
{
NodeBasedEditor window = GetWindow<NodeBasedEditor>();
window.titleContent = new GUIContent("Node Based Editor");
}

private void OnEnable()
{
nodeStyle = new GUIStyle();
nodeStyle.normal.background = EditorGUIUtility.Load("builtin skins/darkskin/images/node1.png") as Texture2D;
nodeStyle.border = new RectOffset(12, 12, 12, 12);

selectedNodeStyle = new GUIStyle();
selectedNodeStyle.normal.background = EditorGUIUtility.Load("builtin skins/darkskin/images/node1 on.png") as Texture2D;
selectedNodeStyle.border = new RectOffset(12, 12, 12, 12);

inPointStyle = new GUIStyle();
inPointStyle.normal.background = EditorGUIUtility.Load("builtin skins/darkskin/images/btn left.png") as Texture2D;
inPointStyle.active.background = EditorGUIUtility.Load("builtin skins/darkskin/images/btn left on.png") as Texture2D;
inPointStyle.border = new RectOffset(4, 4, 12, 12);

outPointStyle = new GUIStyle();
outPointStyle.normal.background = EditorGUIUtility.Load("builtin skins/darkskin/images/btn right.png") as Texture2D;
outPointStyle.active.background = EditorGUIUtility.Load("builtin skins/darkskin/images/btn right on.png") as Texture2D;
outPointStyle.border = new RectOffset(4, 4, 12, 12);
}

private void OnGUI()
{
DrawGrid(20, 0.2f, Color.gray);
DrawGrid(100, 0.4f, Color.gray);

DrawNodes();
DrawConnections();

DrawConnectionLine(Event.current);

ProcessNodeEvents(Event.current);
ProcessEvents(Event.current);

if (GUI.changed) Repaint();
}

private void DrawGrid(float gridSpacing, float gridOpacity, Color gridColor)
{
int widthDivs = Mathf.CeilToInt(position.width / gridSpacing);
int heightDivs = Mathf.CeilToInt(position.height / gridSpacing);

Handles.BeginGUI();
Handles.color = new Color(gridColor.r, gridColor.g, gridColor.b, gridOpacity);

offset += drag * 0.5f;
Vector3 newOffset = new Vector3(offset.x % gridSpacing, offset.y % gridSpacing, 0);

for (int i = 0; i < widthDivs; i++)
{
Handles.DrawLine(new Vector3(gridSpacing * i, -gridSpacing, 0) + newOffset, new Vector3(gridSpacing * i, position.height, 0f) + newOffset);
}

for (int j = 0; j < heightDivs; j++)
{
Handles.DrawLine(new Vector3(-gridSpacing, gridSpacing * j, 0) + newOffset, new Vector3(position.width, gridSpacing * j, 0f) + newOffset);
}

Handles.color = Color.white;
Handles.EndGUI();
}

private void DrawNodes()
{
if (nodes != null)
{
for (int i = 0; i < nodes.Count; i++)
{
nodes[i].Draw();
}
}
}

private void DrawConnections()
{
if (connections != null)
{
for (int i = 0; i < connections.Count; i++)
{
connections[i].Draw();
}
}
}

private void ProcessEvents(Event e)
{
drag = Vector2.zero;

switch (e.type)
{
case EventType.MouseDown:
if (e.button == 0)
{
ClearConnectionSelection();
}

if (e.button == 1)
{
ProcessContextMenu(e.mousePosition);
}
break;

case EventType.MouseDrag:
if (e.button == 0)
{
OnDrag(e.delta);
}
break;
}
}

private void ProcessNodeEvents(Event e)
{
if (nodes != null)
{
for (int i = nodes.Count - 1; i >= 0; i--)
{
bool guiChanged = nodes[i].ProcessEvents(e);

if (guiChanged)
{
GUI.changed = true;
}
}
}
}

GUI.changed = true;
}

if (selectedOutPoint != null && selectedInPoint == null)
{
Handles.DrawBezier(
selectedOutPoint.rect.center,
e.mousePosition,
selectedOutPoint.rect.center - Vector2.left * 50f,
e.mousePosition + Vector2.left * 50f,
Color.white,
null,
2f
);

GUI.changed = true;
}
}

private void ProcessContextMenu(Vector2 mousePosition)
{
GenericMenu genericMenu = new GenericMenu();
genericMenu.AddItem(new GUIContent("Add node"), false, () => OnClickAddNode(mousePosition));
genericMenu.ShowAsContext();
}

private void OnDrag(Vector2 delta)
{
drag = delta;

if (nodes != null)
{
for (int i = 0; i < nodes.Count; i++)
{
nodes[i].Drag(delta);
}
}

GUI.changed = true;
}

private void OnClickAddNode(Vector2 mousePosition)
{
if (nodes == null)
{
nodes = new List<Node>();
}

nodes.Add(new Node(mousePosition, 200, 50, nodeStyle, selectedNodeStyle, inPointStyle, outPointStyle, OnClickInPoint, OnClickOutPoint, OnClickRemoveNode));
}

private void OnClickInPoint(ConnectionPoint inPoint)
{
selectedInPoint = inPoint;

if (selectedOutPoint != null)
{
if (selectedOutPoint.node != selectedInPoint.node)
{
CreateConnection();
ClearConnectionSelection();
}
else
{
ClearConnectionSelection();
}
}
}

private void OnClickOutPoint(ConnectionPoint outPoint)
{
selectedOutPoint = outPoint;

if (selectedInPoint != null)
{
if (selectedOutPoint.node != selectedInPoint.node)
{
CreateConnection();
ClearConnectionSelection();
}
else
{
ClearConnectionSelection();
}
}
}

private void OnClickRemoveNode(Node node)
{
if (connections != null)
{
List<Connection> connectionsToRemove = new List<Connection>();

for (int i = 0; i < connections.Count; i++)
{
if (connections[i].inPoint == node.inPoint || connections[i].outPoint == node.outPoint)
{
connectionsToRemove.Add(connections[i]);
}
}

for (int i = 0; i < connectionsToRemove.Count; i++)
{
connections.Remove(connectionsToRemove[i]);
}

connectionsToRemove = null;
}

nodes.Remove(node);
}

private void OnClickRemoveConnection(Connection connection)
{
connections.Remove(connection);
}

private void CreateConnection()
{
if (connections == null)
{
connections = new List<Connection>();
}

connections.Add(new Connection(selectedInPoint, selectedOutPoint, OnClickRemoveConnection));
}

private void ClearConnectionSelection()
{
selectedInPoint = null;
selectedOutPoint = null;
}
}

using System;
using UnityEditor;
using UnityEngine;

public class Node
{
public Rect rect;
public string title;
public bool isDragged;
public bool isSelected;

public ConnectionPoint inPoint;
public ConnectionPoint outPoint;

public GUIStyle style;
public GUIStyle defaultNodeStyle;
public GUIStyle selectedNodeStyle;

public Action<Node> OnRemoveNode;

public Node(Vector2 position, float width, float height, GUIStyle nodeStyle, GUIStyle selectedStyle, GUIStyle inPointStyle, GUIStyle outPointStyle, Action<ConnectionPoint> OnClickInPoint, Action<ConnectionPoint> OnClickOutPoint, Action<Node> OnClickRemoveNode)
{
rect = new Rect(position.x, position.y, width, height);
style = nodeStyle;
inPoint = new ConnectionPoint(this, ConnectionPointType.In, inPointStyle, OnClickInPoint);
outPoint = new ConnectionPoint(this, ConnectionPointType.Out, outPointStyle, OnClickOutPoint);
defaultNodeStyle = nodeStyle;
selectedNodeStyle = selectedStyle;
OnRemoveNode = OnClickRemoveNode;
}

public void Drag(Vector2 delta)
{
rect.position += delta;
}

public void Draw()
{
inPoint.Draw();
outPoint.Draw();
GUI.Box(rect, title, style);
}

public bool ProcessEvents(Event e)
{
switch (e.type)
{
case EventType.MouseDown:
if (e.button == 0)
{
if (rect.Contains(e.mousePosition))
{
isDragged = true;
GUI.changed = true;
isSelected = true;
style = selectedNodeStyle;
}
else
{
GUI.changed = true;
isSelected = false;
style = defaultNodeStyle;
}
}

if (e.button == 1 && isSelected && rect.Contains(e.mousePosition))
{
ProcessContextMenu();
e.Use();
}
break;

case EventType.MouseUp:
isDragged = false;
break;

case EventType.MouseDrag:
if (e.button == 0 && isDragged)
{
Drag(e.delta);
e.Use();
return true;
}
break;
}

return false;
}

private void ProcessContextMenu()
{
GenericMenu genericMenu = new GenericMenu();
genericMenu.AddItem(new GUIContent("Remove node"), false, OnClickRemoveNode);
genericMenu.ShowAsContext();
}

private void OnClickRemoveNode()
{
if (OnRemoveNode != null)
{
OnRemoveNode(this);
}
}
}

using System;
using UnityEditor;
using UnityEngine;

public class Connection
{
public ConnectionPoint inPoint;
public ConnectionPoint outPoint;
public Action<Connection> OnClickRemoveConnection;

public Connection(ConnectionPoint inPoint, ConnectionPoint outPoint, Action<Connection> OnClickRemoveConnection)
{
this.inPoint = inPoint;
this.outPoint = outPoint;
this.OnClickRemoveConnection = OnClickRemoveConnection;
}

public void Draw()
{
Handles.DrawBezier(
inPoint.rect.center,
outPoint.rect.center,
inPoint.rect.center + Vector2.left * 50f,
outPoint.rect.center - Vector2.left * 50f,
Color.white,
null,
2f
);

if (Handles.Button((inPoint.rect.center + outPoint.rect.center) * 0.5f, Quaternion.identity, 4, 8, Handles.RectangleCap))
{
if (OnClickRemoveConnection != null)
{
OnClickRemoveConnection(this);
}
}
}
}

using System;
using UnityEngine;

public enum ConnectionPointType { In, Out }

public class ConnectionPoint
{
public Rect rect;

public ConnectionPointType type;

public Node node;

public GUIStyle style;

public Action<ConnectionPoint> OnClickConnectionPoint;

public ConnectionPoint(Node node, ConnectionPointType type, GUIStyle style, Action<ConnectionPoint> OnClickConnectionPoint)
{
this.node = node;
this.type = type;
this.style = style;
this.OnClickConnectionPoint = OnClickConnectionPoint;
rect = new Rect(0, 0, 10f, 20f);
}

public void Draw()
{
rect.y = node.rect.y + (node.rect.height * 0.5f) - rect.height * 0.5f;

switch (type)
{
case ConnectionPointType.In:
rect.x = node.rect.x - rect.width + 8f;
break;

case ConnectionPointType.Out:
rect.x = node.rect.x + node.rect.width - 8f;
break;
}

if (GUI.Button(rect, "", style))
{
if (OnClickConnectionPoint != null)
{
OnClickConnectionPoint(this);
}
}
}
}

————————————————
版权声明：本文为CSDN博主「u010019717」的原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/u010019717/article/details/80300136

来源：CSDN

作者：Rick__

链接：https://blog.csdn.net/Rick__/article/details/103970896

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