原理：
用相机拍摄预制体，生成一张预览图
需要注意：
1) GameObject.Instantiate实例化预制体后，要等待几帧才能获取到正确的Transform参数，刚创建就获取可能是不对的。
2) 预制体预览有两种实现方式，一种是继承Editor然后重写OnPreviewGUI；另一种是继承ObjectPreview然后重写OnPreviewGUI；
这边选择后面这种，因为第1种，对于场景下的嵌套预制体，预览界面不起作用。
3) 如果预制体的根节点有Image组件，只有在Project窗口中选择预制体时才能预览；其他方式只有Image图片的预览，目前未找到解决方式，猜测可能ImageEditor的OnPreviewGUI优先级更高?
#if UNITY_EDITOR
using System.IO;
using UnityEditor;
using UnityEditor.Experimental.SceneManagement;
using UnityEngine;
[CustomPreview(typeof(GameObject))]
public class PrefabPreview : ObjectPreview
{
private string m_UGUIPrefabPath;
private int m_Frame = -1;
private string m_PreviewFilePath;
private void OnEditorUpdate()
{
if (m_Frame > 0)
{
m_Frame--;
if (0 == m_Frame)
{
var previewGo = GameObject.Find("___preview");
if (null != previewGo)
{
if (string.IsNullOrEmpty(m_PreviewFilePath))
{
Debug.LogError($"m_PreviewFilePath none, PreviewEditor Change?");
GameObject.DestroyImmediate(previewGo);
}
else
{
previewGo.name = "preview_ready";
var tex = AssetPreviewHelper.GetAssetPreview(previewGo);
AssetPreviewHelper.SaveTexture2D(tex, m_PreviewFilePath);
}
}
m_Frame = -1;
EditorApplication.update -= OnEditorUpdate;
AssetPreviewHelper.RepaintInspector();
}
}
}
private bool IsUGUIPrefab()
{
m_UGUIPrefabPath = "";
var prefabPath = AssetDatabase.GetAssetPath(target);
var targetGo = (GameObject)target;
if (string.IsNullOrEmpty(prefabPath))
{
if (PrefabUtility.IsAnyPrefabInstanceRoot(targetGo)) //场景中的嵌套预制体
prefabPath = PrefabUtility.GetPrefabAssetPathOfNearestInstanceRoot(targetGo);
else
{
var stage = PrefabStageUtility.GetCurrentPrefabStage();
if (null != stage) //预制体编辑界面
prefabPath = stage.prefabAssetPath;
}
}
if (string.IsNullOrEmpty(prefabPath))
return false;
var rtf = targetGo.GetComponent<RectTransform>();
if (null != rtf)
{
m_UGUIPrefabPath = prefabPath;
return true;
}
return false;
}
public override bool HasPreviewGUI()
{
if (IsUGUIPrefab())
return true;
return base.HasPreviewGUI();
}
public override void OnPreviewGUI(Rect r, GUIStyle background)
{
if (string.IsNullOrEmpty(m_UGUIPrefabPath))
{
base.OnPreviewGUI(r, background);
return;
}
var preview = AssetPreview.GetAssetPreview(target);
if (null == preview)
{
var guid = AssetDatabase.AssetPathToGUID(m_UGUIPrefabPath);
var previewFilePath = Path.Combine("_Preview", $"{guid}.png");
if (File.Exists(previewFilePath))
{
var imgBytes = File.ReadAllBytes(previewFilePath);
Texture2D tex = new Texture2D(2, 2);
tex.LoadImage(imgBytes);
preview = tex;
}
}
if (preview)
PreviewEditor.OnGUI_PreviewImage(r, preview);
}
//生成预览图
private void RefreshPreviewImage(string previewFilePath)
{
var previewGo = GameObject.Find("___preview");
if (null != previewGo)
{
Debug.LogWarning("last preview not finish, force terminate!");
GameObject.DestroyImmediate(previewGo);
}
previewGo = GameObject.Instantiate((GameObject)target);
//previewGo.hideFlags = HideFlags.HideAndDontSave;
previewGo.name = "___preview";
previewGo.transform.position = new Vector3(-1000, -1000, -1000); //远一点, 这样才看不到
m_Frame = 2; //等待几帧
m_PreviewFilePath = previewFilePath;
EditorApplication.update -= OnEditorUpdate;
EditorApplication.update += OnEditorUpdate;
}
public override void OnPreviewSettings()
{
base.OnPreviewSettings();
if (GUILayout.Button("刷新", "preButton"))
{
var guid = AssetDatabase.AssetPathToGUID(m_UGUIPrefabPath);
var previewFilePath = Path.Combine("_Preview", $"{guid}.png");
RefreshPreviewImage(previewFilePath);
}
}
}
#endif
场景嵌套预制体
预制体编辑界面
资源管理其中选择预制体时
#if UNITY_EDITOR
using System;
using System.IO;
using System.Reflection;
using UnityEngine;
using UnityEngine.UI;
public static class AssetPreviewHelper
{
public static Texture2D GetAssetPreview(GameObject cloneGo)
{
GameObject rootGo = null;
var cameraGo = new GameObject("render camera", typeof(Camera));
var cameraTransform = cameraGo.transform;
var renderCamera = cameraGo.GetComponent<Camera>();
renderCamera.backgroundColor = new Color(0.8f, 0.8f, 0.8f, 0.1f);
renderCamera.clearFlags = CameraClearFlags.Color;
renderCamera.cameraType = CameraType.SceneView;
renderCamera.cullingMask = 1 << 31;
Bounds bounds;
var cloneTransform = cloneGo.transform;
bool isUINode = false;
if (cloneTransform is RectTransform)
{
//如果是UGUI节点的话就要把它们放在Canvas下了
var canvasGo = new GameObject("render canvas", typeof(Canvas));
var canvasRtf = canvasGo.GetComponent<RectTransform>();
SetAsDesignSize(canvasRtf);
canvasRtf.position = new Vector3(-1000, -1000, -1000); //远一点, 这样才看不到
canvasGo.layer = 31;//放在31层，摄像机也只渲染此层的，避免混入了奇怪的东西
rootGo = canvasGo;
var canvas = canvasGo.GetComponent<Canvas>();
canvas.renderMode = RenderMode.WorldSpace;
canvas.worldCamera = renderCamera;
cameraTransform.SetParent(canvasRtf, false);
cloneTransform.SetParent(canvasRtf, false);
cloneTransform.localPosition = Vector3.zero;
if (cloneTransform.GetComponent<Canvas>()) //根节点有Canvas组件, 只考虑根节点的大小
{
var cloneRtf = (RectTransform)cloneTransform;
var anchorDiff = cloneRtf.anchorMax - cloneRtf.anchorMin;
bool haveStretch = !Mathf.Approximately(anchorDiff.sqrMagnitude, float.Epsilon);
if (haveStretch)
{
var cavs = cloneTransform.GetComponent<CanvasScaler>();
if (cavs && cavs.uiScaleMode == CanvasScaler.ScaleMode.ScaleWithScreenSize)
{
var size = cavs.referenceResolution;
cloneRtf.SetSizeWithCurrentAnchors(RectTransform.Axis.Horizontal, size.x);
cloneRtf.SetSizeWithCurrentAnchors(RectTransform.Axis.Vertical, size.y);
}
}
var tempWorldCorners = new Vector3[4];
cloneRtf.GetWorldCorners(tempWorldCorners);
bounds = new Bounds(tempWorldCorners[0], Vector3.zero); //左下
bounds.Encapsulate(tempWorldCorners[2]); //右上
}
else
{
bounds = GetBounds(cloneGo);
}
isUINode = true;
}
else
{
rootGo = cloneGo;
cameraTransform.SetParent(cloneTransform, false);
bounds = GetBounds(cloneGo);
}
var allTransforms = cloneGo.GetComponentsInChildren<Transform>();
foreach (Transform trans in allTransforms)
trans.gameObject.layer = 31;
var vMin = bounds.min;
var vMax = bounds.max;
float texWidth = 128;
float texHeight = 128;
var center = bounds.center;
var pos = cameraTransform.position;
pos.x = center.x;
pos.y = center.y;
if (isUINode)
{
pos.z -= 100;
cameraTransform.position = pos;
renderCamera.orthographic = true;
float width = vMax.x - vMin.x;
float height = vMax.y - vMin.y;
if (width > height) //宽不变, 调整高
{
if (width < 64) //原来就比64小, 直接用原大小
texWidth = width;
else
texWidth = Mathf.Max(64, width * 0.5f); //最小64
texWidth = Mathf.Min(768, texWidth); //最大768
renderCamera.orthographicSize = height * 0.5f;
texHeight = texWidth * height / width;
}
else
{
if (height < 64) //原来就比64小, 直接用原大小
texHeight = height;
else
texHeight = Mathf.Max(64, height * 0.5f); //最小64
texHeight = Mathf.Min(768, texHeight); //最大768
renderCamera.orthographicSize = height * 0.5f;
texWidth = texHeight * width / height;
}
Debug.Log($"ui:{width}x{height}, tex:{texWidth}x{texHeight}");
}
else
{
pos.z -= vMax.z + (vMax.z - vMin.z); //z往前一点
cameraTransform.position = pos;
cameraTransform.LookAt(center);
var size = bounds.size;
int angle = (int)(Mathf.Atan2(size.y * 0.5f, size.z) * Mathf.Rad2Deg * 2); //Camera在(0,0,0)处, 拍摄Bounds包围盒
renderCamera.fieldOfView = angle;
}
var camRT = new RenderTexture((int)texWidth, (int)texHeight, 0, RenderTextureFormat.Default);
renderCamera.targetTexture = camRT;
renderCamera.Render();
var tex = RTToTexture2D(camRT);
UnityEngine.Object.DestroyImmediate(rootGo);
return tex;
}
public static Texture2D RTToTexture2D(RenderTexture rt)
{
var oldActiveRT = RenderTexture.active;
RenderTexture.active = rt;
var tex = new Texture2D(rt.width, rt.height, TextureFormat.RGBAHalf, false);
tex.ReadPixels(new Rect(0, 0, rt.width, rt.height), 0, 0);
tex.Apply();
RenderTexture.active = oldActiveRT;
return tex;
}
public static Bounds GetBounds(GameObject go)
{
var vMin = new Vector3(float.MaxValue, float.MaxValue, float.MaxValue);
var vMax = new Vector3(float.MinValue, float.MinValue, float.MinValue);
var renders = go.GetComponentsInChildren<MeshRenderer>();
if (renders.Length > 0)
{
for (int i = 0; i < renders.Length; i++)
{
var bounds = renders[i].bounds;
vMin = Vector3.Min(vMin, bounds.min);
vMax = Vector3.Max(vMax, bounds.max);
}
}
else
{
var rectTrans = go.GetComponentsInChildren<RectTransform>();
var tempWorldCorners = new Vector3[4];
for (int i = 0; i < rectTrans.Length; i++)
{
var rtf = rectTrans[i];
var s = rtf.lossyScale;
//if (s.x <= 3 && s.y <= 3 && s.z <= 3)
{
//获取节点的四个角的世界坐标，分别按顺序为左下, 左上, 右上, 右下
rtf.GetWorldCorners(tempWorldCorners);
vMin = Vector3.Min(vMin, tempWorldCorners[0]);
vMax = Vector3.Max(vMax, tempWorldCorners[2]);
}
}
}
var bounds_2 = new Bounds(vMin, Vector3.zero);
bounds_2.Encapsulate(vMax);
//Debug.Log($"vMin:{vMin}, vMax:{vMax}, size:{bounds_2.size}");
return bounds_2;
}
public static void SaveTexture2D(Texture2D tex, string filePath)
{
var dirPath = Path.GetDirectoryName(filePath);
if (!Directory.Exists(dirPath))
Directory.CreateDirectory(dirPath);
byte[] texBytes = tex.EncodeToPNG();
File.WriteAllBytes(filePath, texBytes);
}
//设置为设计分辨率
private static void SetAsDesignSize(RectTransform rtf)
{
var cavs = GameObject.FindObjectOfType<CanvasScaler>();
if (cavs && cavs.uiScaleMode == CanvasScaler.ScaleMode.ScaleWithScreenSize)
{
var size = cavs.referenceResolution;
rtf.sizeDelta = size;
return;
}
rtf.sizeDelta = GetGameViewSize();
}
public static Vector2 GetGameViewSize()
{
try
{
var type_GameView = System.Type.GetType("UnityEditor.GameView,UnityEditor");
var mi_GetMainGameView = type_GameView.GetMethod("GetMainGameView", BindingFlags.NonPublic | BindingFlags.Static);
var gameView = (UnityEditor.EditorWindow)mi_GetMainGameView.Invoke(null, null);
var prop_currentGameViewSize = gameView.GetType().GetProperty("currentGameViewSize", BindingFlags.NonPublic | BindingFlags.Instance);
object[] emptyObjArr = null; // new object[0] { };
var gameViewSize = prop_currentGameViewSize.GetValue(gameView, emptyObjArr);
var type_GameViewSize = gameViewSize.GetType();
var w = (int)type_GameViewSize.GetProperty("width", BindingFlags.Public | BindingFlags.Instance).GetValue(gameViewSize, emptyObjArr);
var h = (int)type_GameViewSize.GetProperty("height", BindingFlags.Public | BindingFlags.Instance).GetValue(gameViewSize, emptyObjArr);
return new Vector2(w, h);
}
catch (Exception ex)
{
}
return new Vector2(Screen.width, Screen.height);
}
public static void RepaintInspector()
{
var windows = UnityEngine.Resources.FindObjectsOfTypeAll<UnityEditor.EditorWindow>();
foreach (var win in windows)
{
if (win.titleContent.text == "Inspector")
win.Repaint();
}
}
}
#endif
参考
[Unity 3d] UGUI-Editor（UGUI编辑器增强工具） - GitHub - 简书 (jianshu.com)
GitHub - liuhaopen/UGUI-Editor: Unity UGUI editor tools,improve the efficiency of ui development.
获取unity prefab的预览图像 - 露夕逝 - 博客园 (cnblogs.com)
为Unity的新版ugui的Prefab生成预览图_unity ui prefab 预览图-CSDN博客
Unity3D 在 Inspector 中预览场景_unity3d怎么预览-CSDN博客
GitHub - liuhaopen/UGUI-Editor: Unity UGUI editor tools,improve the efficiency of ui development.
标签：预览,GameObject,height,tex,var,预制,new,Inspector From： https://www.cnblogs.com/sailJs/p/17746235.html