unity3d 的区域截图

在Unity3D中，你可以使用RenderTexture来实现区域截图。以下是一个简单的示例代码：

using UnityEngine;
using System.Collections;

public class Screenshot : MonoBehaviour
{
    public int captureWidth = 256;
    public int captureHeight = 256;
    public Camera camera;

    private RenderTexture rt;

    void Start()
    {
        rt = new RenderTexture(captureWidth, captureHeight, 24);
    }

    void OnGUI()
    {
        if (GUI.Button(new Rect(10, 10, 100, 30), "Capture"))
        {
            StartCoroutine(CaptureScreenshot());
        }
    }

    IEnumerator CaptureScreenshot()
    {
        // Set the target texture of the camera to the render texture we created
        camera.targetTexture = rt;
        camera.Render();

        // Create a new Texture2D and read the pixels from the render texture into it
        Texture2D texture = new Texture2D(captureWidth, captureHeight, TextureFormat.RGB24, false);
        RenderTexture.active = rt;
        texture.ReadPixels(new Rect(0, 0, captureWidth, captureHeight), 0, 0);
        texture.Apply();

        // Reset the camera's target texture and active render texture
        camera.targetTexture = null;
        RenderTexture.active = null;

        // Save the screenshot as a PNG file
        byte[] bytes = texture.EncodeToPNG();
        System.IO.File.WriteAllBytes(Application.dataPath + "/Screenshot.png", bytes);

        // Destroy the temporary objects we created
        DestroyImmediate(rt);
        DestroyImmediate(texture);

        yield return null;
    }
}

该示例代码将在屏幕上显示一个按钮，“Capture”，当用户点击该按钮时，它将使用RenderTexture来截取摄像机视野中的特定区域，并将其保存为PNG文件。你可以根据自己的需求调整截图的大小和位置。