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 GUIContent
insertContent = new GUIContent("+", "duplicate this point"),
deleteContent = new GUIContent("-", "delete this point"),
pointContent = GUIContent.none,
teleportContent = new GUIContent("T");
private static GUILayoutOption
buttonWidth = GUILayout.MaxWidth(20f),
colorWidth = GUILayout.MaxWidth(50f);
private SerializedObject star;
private SerializedProperty
points,
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 GUIContent
insertContent = new GUIContent("+", "duplicate this point"),
deleteContent = new GUIContent("-", "delete this point"),
pointContent = GUIContent.none,
teleportContent = new GUIContent("T");
private static GUILayoutOption
buttonWidth = GUILayout.MaxWidth(20f),
colorWidth = GUILayout.MaxWidth(50f);
private SerializedObject star;
private SerializedProperty
points,
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.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 GUIContent
insertContent = new GUIContent("+", "duplicate this point"),
deleteContent = new GUIContent("-", "delete this point"),
pointContent = GUIContent.none,
teleportContent = new GUIContent("T");
private static GUILayoutOption
buttonWidth = GUILayout.MaxWidth(20f),
colorWidth = GUILayout.MaxWidth(50f);
private SerializedObject star;
private SerializedProperty
points,
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.offset),
newPoint = Handles.FreeMoveHandle
(oldPoint, Quaternion.identity, 0.04f, pointSnap, Handles.DotCap);
if(oldPoint != newPoint){
star.points.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 GUIContent
insertContent = new GUIContent("+", "duplicate this point"),
deleteContent = new GUIContent("-", "delete this point"),
pointContent = GUIContent.none,
teleportContent = new GUIContent("T");
oints");