[Unity基础]RenderTexture

参考链接：

https://www.cnblogs.com/Jimm/p/5951362.html

一.相关API

1.Texture2D.ReadPixels

从RenderTexture.active中复制像素，以左下角为原点。

2.MonoBehaviour.OnPostRender

当相机渲染完所有物体就会调用该方法，并且只有当这个脚本挂在相机时才会调用。

二.测试

新建一个场景，新建一个camera和一个go，把go设置为一个单独的层，让camera单独照这个层，主camera不要照这个层。调整camera的深度和targetTexture。

 using UnityEngine;
 using System.Collections;
 using UnityEngine.UI;
 using System.IO;

 public class TestRenderTexture : MonoBehaviour {

     public Camera camera;
     public RawImage rawImage;
     bool isScreenShot = false;

     void Update()
     {
         //将镜头的画面保存到本地
         if (Input.GetKeyDown(KeyCode.Q))
         {
             Texture2D tex = RenderTexture2Texture2D(camera.targetTexture);

             //展示
             rawImage.texture = tex;

             //保存到本地
             byte[] bytes = tex.EncodeToPNG();
             File.WriteAllBytes(Application.dataPath + "/RenderTexture/Test.png", bytes);
             UnityEditor.AssetDatabase.Refresh();
         }

         //屏幕截图(方法1)
         if (Input.GetKeyDown(KeyCode.W))
         {
             StartCoroutine(ScreenShotIEnumerator());
         }

         //屏幕截图(方法2)
         if (Input.GetKeyDown(KeyCode.E))
         {
             isScreenShot = true;
         }
     }

     public IEnumerator ScreenShotIEnumerator()
     {
         yield return new WaitForEndOfFrame();
         rawImage.texture = ScreenShot();
     }

     private void OnPostRender()
     {
         //Debug.Log("OnPostRender");
         if (isScreenShot)
         {
             isScreenShot = false;
             rawImage.texture = ScreenShot();
         }
     }

     //屏幕截图
     public Texture2D ScreenShot()
     {
         Texture2D tex = new Texture2D(Screen.width, Screen.height, TextureFormat.ARGB32, false);
         tex.ReadPixels(new Rect(, , Screen.width, Screen.height), , );
         tex.Apply();
         return tex;
     }

     //RenderTexture转Texture2D
     public Texture2D RenderTexture2Texture2D(RenderTexture rt)
     {
         RenderTexture preRT = RenderTexture.active;
         RenderTexture.active = rt;
         Texture2D tex = new Texture2D(rt.width, rt.height, TextureFormat.ARGB32, false);
         tex.ReadPixels(new Rect(, , rt.width, rt.height), , );
         tex.Apply();
         RenderTexture.active = preRT;
         return tex;
     }
 }