Unity教程之-制作闪亮的星星Star（四）：Unity Editor编辑器实现Undo

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继续上篇文章《Unity教程之-制作闪亮的星星Star（三）：给Star创建Unity Editor编辑器》，在Unity中没有一种简单的方法来支持Undo事件，但我们可以做到接近支持。在我们的案例中，我们可以检查ValidateCommand事件是否发生，来判断Undo操作。当前被选中的对象这个事件的目标，我们假设它被修改过。

What’s a ValidateCommand?

ValidateCommand is a type of GUI event, which indicates that some special action happened, like undo or redo. So why isn’t it called something like ExecuteCommand? Actually, that command type exists as well. While they have a slightly different meaning, in practice you use them for the exact same purpose. Unfortunately, depening on exactly where you’re checking and how you’re constructing your GUI, either one or the other event happens, but not both. Why this is so, I do not know.
So to be perfectly safe, you have to check for both command types. In this case, however, you can suffice with checking ValidateCommand.

using UnityEditor;
using UnityEngine;[CustomEditor(typeof(Star))]
public class StarInspector : Editor {private static GUIContentinsertContent = new GUIContent("+", "duplicate this point"),deleteContent = new GUIContent("-", "delete this point"),pointContent = GUIContent.none,teleportContent = new GUIContent("T");private static GUILayoutOptionbuttonWidth = GUILayout.MaxWidth(20f),colorWidth = GUILayout.MaxWidth(50f);private SerializedObject star;private SerializedPropertypoints,frequency,centerColor;private int teleportingElement;void OnEnable () { … }public override void OnInspectorGUI () {star.Update();GUILayout.Label("Points");for(int i = 0; i < points.arraySize; i++){EditorGUILayout.BeginHorizontal();SerializedProperty point = points.GetArrayElementAtIndex(i);EditorGUILayout.PropertyField(point.FindPropertyRelative("offset"), pointContent);EditorGUILayout.PropertyField(point.FindPropertyRelative("color"), pointContent, colorWidth);if(GUILayout.Button(teleportContent, EditorStyles.miniButtonLeft, buttonWidth)){if(teleportingElement >= 0){points.MoveArrayElement(teleportingElement, i);teleportingElement = -1;teleportContent.tooltip = "start teleporting this point";}else{teleportingElement = i;teleportContent.tooltip = "teleport here";}}if(GUILayout.Button(insertContent, EditorStyles.miniButtonMid, buttonWidth)){points.InsertArrayElementAtIndex(i);}if(GUILayout.Button(deleteContent, EditorStyles.miniButtonRight, buttonWidth)){points.DeleteArrayElementAtIndex(i);}EditorGUILayout.EndHorizontal();}if(teleportingElement >= 0){GUILayout.Label("teleporting point " + teleportingElement);}EditorGUILayout.PropertyField(frequency);EditorGUILayout.PropertyField(centerColor);if(star.ApplyModifiedProperties() ||(Event.current.type == EventType.ValidateCommand &&Event.current.commandName == "UndoRedoPerformed")){((Star)target).UpdateStar();}}
}

最后，一个舒服的编辑过程！还有什么需要做吗？在编辑器的右上角有一个齿轮图标能够重置组件。当我们重置Star组件的时候我们的Mesh没有及时更新。

你可以定义Reset方法来监听一个组件的重置。这事Unity为Editor及其子类提供的一个方法。当这个事件发生，我们只要及时更新我们的星星就可以了。

using System;
using UnityEngine;[ExecuteInEditMode, RequireComponent(typeof(MeshFilter), typeof(MeshRenderer))]
public class Star : MonoBehaviour {[Serializable]public class Point { … }public Point[] points;public int frequency = 1;public Color centerColor;private Mesh mesh;private Vector3[] vertices;private Color[] colors;private int[] triangles;public void UpdateStar () { … }void OnEnable () { … }void OnDisable () { … }void Reset () {UpdateStar();}
}

OK我们开始写Reset。我们要做什么？我们来试试prefabs？

现在使用prefabs对于我们star并没有太多意义，因为每一个star都拥有自己的独立的Mesh。如果你想使用很多个一样的star，那在建立一个3D模型并且导入Mesh是一个好主意。这样所有的star就共享了同一个Mesh。但假设我们使用prefab，就可以实例化多个同样的star然后我们还能够调整它们。

你只要简单的拖拽一个star从层级视图到项目视图，就能建立一个prefab。对prefab的更新能够影响全部的prefab实例，因为每个prefab的修改都会触发OnDisable和OnEnable。将一个实例回复成prefab同样的状态它依然能够工作。

唯一我们没有完全做好的事情是prefab的MeshFilter会显示它的Mesh类型不匹配。这事因为prefab是一个实际的资源，而动态生成的Mesh不是。这不影响功能，但还是让我们解决它吧。

一个修改后提示类型不匹配的prefab

为了停止prefab生成它的Mesh，我们不能再调用UpdateStar方法。不幸的是，这代表我们将不能再看到预览了。我们可以用PrefabUtility.GetPrefabType方法来检测编辑窗口当前的对象是不是prefab。如果是，我们简单的不更新它就行了。

using UnityEditor;
using UnityEngine;[CustomEditor(typeof(Star))]
public class StarInspector : Editor {private static GUIContentinsertContent = new GUIContent("+", "duplicate this point"),deleteContent = new GUIContent("-", "delete this point"),pointContent = GUIContent.none,teleportContent = new GUIContent("T");private static GUILayoutOptionbuttonWidth = GUILayout.MaxWidth(20f),colorWidth = GUILayout.MaxWidth(50f);private SerializedObject star;private SerializedPropertypoints,frequency,centerColor;private int teleportingElement;void OnEnable () { … }public override void OnInspectorGUI () {star.Update();GUILayout.Label("Points");for(int i = 0; i < points.arraySize; i++){EditorGUILayout.BeginHorizontal();SerializedProperty point = points.GetArrayElementAtIndex(i);EditorGUILayout.PropertyField(point.FindPropertyRelative("offset"), pointContent);EditorGUILayout.PropertyField(point.FindPropertyRelative("color"), pointContent, colorWidth);if(GUILayout.Button(teleportContent, EditorStyles.miniButtonLeft, buttonWidth)){if(teleportingElement >= 0){points.MoveArrayElement(teleportingElement, i);teleportingElement = -1;teleportContent.tooltip = "start teleporting this point";}else{teleportingElement = i;teleportContent.tooltip = "teleport here";}}if(GUILayout.Button(insertContent, EditorStyles.miniButtonMid, buttonWidth)){points.InsertArrayElementAtIndex(i);}if(GUILayout.Button(deleteContent, EditorStyles.miniButtonRight, buttonWidth)){points.DeleteArrayElementAtIndex(i);}EditorGUILayout.EndHorizontal();}if(teleportingElement >= 0){GUILayout.Label("teleporting point " + teleportingElement);}EditorGUILayout.PropertyField(frequency);EditorGUILayout.PropertyField(centerColor);if(star.ApplyModifiedProperties() ||(Event.current.type == EventType.ValidateCommand &&Event.current.commandName == "UndoRedoPerformed")){if(PrefabUtility.GetPrefabType(target) != PrefabType.Prefab){((Star)target).UpdateStar();}}}
}

prefab没有了Mesh和预览

OK，我们完成了，真的？我没还没有对同时存在多个对象的情况进行支持。试试同时选择多个star。

还没有提供多对象编辑

让我们尝试多对象编辑功能吧。首先，我们需要给类添加一个属性让编辑器提供相应的支持。然后我们需要初始化所有target的SerializedObject，而不再只是一个。我们还需要把任何变化同步到全部的target上。

这样就能在编辑器中支持多个对象了，但如果一些star的point个数不一样，就会出错。因为在Unity的编辑器尝试读取全部点的资料的时候，有些点会不存在。我们可以在获得每个point的数据的时候检查一下这个point是否存在，如果不存在，就停止取值。所以我们只需要显示一个star所拥有的数量的point就可以了。

using UnityEditor;
using UnityEngine;[CanEditMultipleObjects, CustomEditor(typeof(Star))]
public class StarInspector : Editor {private static GUIContentinsertContent = new GUIContent("+", "duplicate this point"),deleteContent = new GUIContent("-", "delete this point"),pointContent = GUIContent.none,teleportContent = new GUIContent("T");private static GUILayoutOptionbuttonWidth = GUILayout.MaxWidth(20f),colorWidth = GUILayout.MaxWidth(50f);private SerializedObject star;private SerializedPropertypoints,frequency,centerColor;private int teleportingElement;void OnEnable () {star = new SerializedObject(targets);points = star.FindProperty("points");frequency = star.FindProperty("frequency");centerColor = star.FindProperty("centerColor");teleportingElement = -1;teleportContent.tooltip = "start teleporting this point";}public override void OnInspectorGUI () {star.Update();GUILayout.Label("Points");for(int i = 0; i < points.arraySize; i++){SerializedPropertypoint = points.GetArrayElementAtIndex(i),offset = point.FindPropertyRelative("offset");if(offset == null){break;}EditorGUILayout.BeginHorizontal();EditorGUILayout.PropertyField(offset, pointContent);EditorGUILayout.PropertyField(point.FindPropertyRelative("color"), pointContent, colorWidth);if(GUILayout.Button(teleportContent, EditorStyles.miniButtonLeft, buttonWidth)){if(teleportingElement >= 0){points.MoveArrayElement(teleportingElement, i);teleportingElement = -1;teleportContent.tooltip = "start teleporting this point";}else{teleportingElement = i;teleportContent.tooltip = "teleport here";}}if(GUILayout.Button(insertContent, EditorStyles.miniButtonMid, buttonWidth)){points.InsertArrayElementAtIndex(i);}if(GUILayout.Button(deleteContent, EditorStyles.miniButtonRight, buttonWidth)){points.DeleteArrayElementAtIndex(i);}EditorGUILayout.EndHorizontal();}if(teleportingElement >= 0){GUILayout.Label("teleporting point " + teleportingElement);}EditorGUILayout.PropertyField(frequency);EditorGUILayout.PropertyField(centerColor);if(star.ApplyModifiedProperties() ||(Event.current.type == EventType.ValidateCommand &&Event.current.commandName == "UndoRedoPerformed")){foreach(Star s in targets){if(PrefabUtility.GetPrefabType(s) != PrefabType.Prefab){s.UpdateStar();}}}}
}

多对象编辑

在场景中编辑 Editing in the Scene View

现在我们拥有了一个很不错的编辑器了，但如果我们能直接在场景里编辑这些point会不会更酷一些？用OnSceneGUI事件，我们可以做到。这个方法会在一个对象被选中即将赋予target时调用。我们不能在这个事件中使用SerializedObject。事实上，你可以认为这个方法与我们编辑器类中的其它部分是完全分离的。

Why does OnSceneGUI mess with target?

Probably for backwards compatibility. Multi-object editing was introduced in Unity 3.5. Versions before that only had the target variable.

using UnityEditor;
using UnityEngine;[CanEditMultipleObjects, CustomEditor(typeof(Star))]
public class StarInspector : Editor {private static GUIContentinsertContent = new GUIContent("+", "duplicate this point"),deleteContent = new GUIContent("-", "delete this point"),pointContent = GUIContent.none,teleportContent = new GUIContent("T");private static GUILayoutOptionbuttonWidth = GUILayout.MaxWidth(20f),colorWidth = GUILayout.MaxWidth(50f);private SerializedObject star;private SerializedPropertypoints,frequency,centerColor;private int teleportingElement;void OnEnable () { … }public override void OnInspectorGUI () { … }void OnSceneGUI () {}
}

让我们设置一个方形的小手柄在star全部的point上面。我们只要在这些point的第一个重复周期里显示手柄就可以了，不需要把全部的重复周期都显示出来。放置这些手柄就好象生成Mesh一样，除了我们使用的是世界坐标系，不是本地坐标系，所以我们要用到star的transform。

我们可以通过Handles.FreeMoveHandle方法来绘制我们的手柄。首先，需要一个世界坐标系的位置，手柄的位置。其次，需要一个绘制手柄的角度，但我们不需要旋转。然后，还需要手柄的尺寸，我们用一个很小的尺寸就够了。我们用一个vector来保存这个尺寸，可以设置成(0.1, 0.1 0.1)。最后一个参数是定义手柄的形状。

How do we convert to world space?

You convert a point from local to world space by appling all transformation matrices of its object hierarchy to it. Unity takes care of this when rendering the scene, but sometimes you need to do it yourself. You can use the Transform.TransformPoint method for this.

using UnityEditor;
using UnityEngine;[CanEditMultipleObjects, CustomEditor(typeof(Star))]
public class StarInspector : Editor {private static Vector3 pointSnap = Vector3.one * 0.1f;private static GUIContentinsertContent = new GUIContent("+", "duplicate this point"),deleteContent = new GUIContent("-", "delete this point"),pointContent = GUIContent.none,teleportContent = new GUIContent("T");private static GUILayoutOptionbuttonWidth = GUILayout.MaxWidth(20f),colorWidth = GUILayout.MaxWidth(50f);private SerializedObject star;private SerializedPropertypoints,frequency,centerColor;private int teleportingElement;void OnEnable () { … }public override void OnInspectorGUI () { … }void OnSceneGUI () {Star star = (Star)target;Transform starTransform = star.transform;float angle = -360f / (star.frequency * star.points.Length);for(int i = 0; i < star.points.Length; i++){Quaternion rotation = Quaternion.Euler(0f, 0f, angle * i);Vector3 oldPoint = starTransform.TransformPoint(rotation * star.points[i].offset);Handles.FreeMoveHandle(oldPoint, Quaternion.identity, 0.04f, pointSnap, Handles.DotCap);}}
}

在场景中添加了控制手柄

现在还有什么可以做到更好吗？你可以点击一个手柄，让它变成黄色。我们需要比较一个手柄的初始化位置和返回位置。如果不同，说明用户拖动了手柄，我们需要将改变同步到star。star的Mesh使用本地坐标系，在把坐标改变保存之前，不要忘记转换坐标。

How do we convert to local space?

You have to perform the exact opposite steps for converting to world space, in reverse order. You can use the Transform.InverseTransformPoint method for this. Note that when going to world space we rotated in local space first, then transformed. So to convert back, we inverse transform first, then inverse rotate in local space.

using UnityEditor;
using UnityEngine;[CanEditMultipleObjects, CustomEditor(typeof(Star))]
public class StarInspector : Editor {private static Vector3 pointSnap = Vector3.one * 0.1f;private static GUIContentinsertContent = new GUIContent("+", "duplicate this point"),deleteContent = new GUIContent("-", "delete this point"),pointContent = GUIContent.none,teleportContent = new GUIContent("T");private static GUILayoutOptionbuttonWidth = GUILayout.MaxWidth(20f),colorWidth = GUILayout.MaxWidth(50f);private SerializedObject star;private SerializedPropertypoints,frequency,centerColor;private int teleportingElement;void OnEnable () { … }public override void OnInspectorGUI () { … }void OnSceneGUI () {Star star = (Star)target;Transform starTransform = star.transform;float angle = -360f / (star.frequency * star.points.Length);for(int i = 0; i < star.points.Length; i++){Quaternion rotation = Quaternion.Euler(0f, 0f, angle * i);Vector3oldPoint = starTransform.TransformPoint(rotation * star.points[i].offset),newPoint = Handles.FreeMoveHandle(oldPoint, Quaternion.identity, 0.04f, pointSnap, Handles.DotCap);if(oldPoint != newPoint){star.points[i].offset = Quaternion.Inverse(rotation) *starTransform.InverseTransformPoint(newPoint);star.UpdateStar();}}}
}

我们可以在场景中编辑了

有用了！不过我们还没支持Undo！这里我们不能靠SerializedObject来解决问题，不过幸好这些手柄可以支持Undo。我们只需要告诉编辑器哪个对象被改变了，我们还应该为这次改变起一个名字。我们可以用Undo.SetSnapshotTarget来做这些事。

What’s a snapshot?

If an undo step would be created for each GUI event, dragging a handle would result in an undo history filled with dozens of tiny modifications. Instead, the handles make a copy – a snapshot – of the object when movement begins and only register a single undo step with the copy when movement ends. SetSnapshotTarget tells the handles which object to use for this.
All Unity editor GUI elements essentialy do the same thing, whether it’s for draggin handles, sliding numbers, typing text, or whatever.

using UnityEditor;
using UnityEngine;[CanEditMultipleObjects, CustomEditor(typeof(Star))]
public class StarInspector : Editor {private static Vector3 pointSnap = Vector3.one * 0.1f;private static GUIContentinsertContent = new GUIContent("+", "duplicate this point"),deleteContent = new GUIContent("-", "delete this point"),pointContent = GUIContent.none,teleportContent = new GUIContent("T");private static GUILayoutOptionbuttonWidth = GUILayout.MaxWidth(20f),colorWidth = GUILayout.MaxWidth(50f);private SerializedObject star;private SerializedPropertypoints,frequency,centerColor;private int teleportingElement;void OnEnable () { … }public override void OnInspectorGUI () { … }void OnSceneGUI () {Star star = (Star)target;Transform starTransform = star.transform;//Undo.SetSnapshotTarget(star, "Move Star Point");Undo.RecordObject(star, "Move star transform");float angle = -360f / (star.frequency * star.points.Length);for(int i = 0; i < star.points.Length; i++){Quaternion rotation = Quaternion.Euler(0f, 0f, angle * i);Vector3oldPoint = starTransform.TransformPoint(rotation * star.points[i].offset),newPoint = Handles.FreeMoveHandle(oldPoint, Quaternion.identity, 0.04f, pointSnap, Handles.DotCap);if(oldPoint != newPoint){star.points[i].offset = Quaternion.Inverse(rotation) *starTransform.InverseTransformPoint(newPoint);star.UpdateStar();}}}
}

<>使用Ctrl + z就可以使用了

这样，我们终于完成了！一个有趣的设计过程，不是吗？下面是工程下载地址！

star.txt (下载32 )

转自：http://www.unity.5helpyou.com/3131.html

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