Unity中截图只渲染有像素的区域，并且压缩保存到本地

需求如标题，话不多说，上代码。

  void Start()    {        cam = gameObject.GetComponent<Camera>();        ScreenHeight = 1024;        ScreenWidth = 1024;    }    public void StartGetCapture()    {        CaptureCamera(cam, rect);    }     Texture2D CaptureCamera(Camera camera)    {        // 创建一个RenderTexture对象          RenderTexture rt = new RenderTexture(ScreenWidth, ScreenHeight, 1);        // 设置相关相机的targetTexture为rt, 并手动渲染相机          camera.targetTexture = rt;        camera.Render();        // 激活这个rt, 并从中中读取像素。          RenderTexture.active = rt;        Texture2D screenShot = new Texture2D(ScreenWidth, ScreenHeight, TextureFormat.ARGB32, false);//TextureFormat设置成ARGB32，只渲染有像素的区域。        float vx = (v1.x > v2.x) ? v2.x : v1.x;      //取较小的x,y作为起始点        float vy = (v1.y > v2.y) ? v2.y : v1.y;        screenShot.ReadPixels(new Rect(0, 0, 1024, 1024), 0, 0, false);//读取像素        screenShot.Apply();        // 重置相关参数，让camera继续在屏幕上显示          camera.targetTexture = null;        RenderTexture.active = null; // JC: added to avoid errors           GameObject.Destroy(rt);        //压缩纹理的尺寸        int targetWidth = (int)(ScreenWidth*0.5f);//压缩的比率        int targetHeight =(int)(ScreenHeight*0.5f);//压缩的比率        Texture2D result = new Texture2D(targetWidth, targetHeight, screenShot.format, false);        float incX = (1.0f / (float)targetWidth);        float incY = (1.0f / (float)targetHeight);        for (int i = 0; i < result.height; ++i)        {            for (int j = 0; j < result.width; ++j)            {                Color newColor = screenShot.GetPixelBilinear((float)j / (float)result.width, (float)i / (float)result.height);                result.SetPixel(j, i, newColor);            }        }        result.Apply();        // 最后将这些纹理数据，保存到一个png图片文件         byte[] bytes = result.EncodeToPNG();        string filename = Application.dataPath + "/Screenshot.png";        System.IO.File.WriteAllBytes(filename, bytes);        return screenShot;    }