webplayer中截屏

因为webplayer的限制，在webplayer上运行unity程序的时候，截屏并不像本地运行程序那样。基本思路是：
1、通过相应的接口把屏幕像素读取到内存，并且encode成png格式；
2、通过wwwform类把png格式的流由服务器接收，并且存在服务器上，做成链接，然用户下载；


unity官方相关的代码例子：

1. // Grab a screen shot and upload it to a CGI script.
   
2. // The CGI script must be able to hande form uploads.
   
3. var screenShotURL= "http://www.my-server.com/cgi-bin/screenshot.pl";
   
4. // Take a screen shot immediately
   
5. function Start() {
   
6.     UploadPNG();
   
7. }
   
8. function UploadPNG() {
   
9.     // We should only read the screen after all rendering is complete
   
10.     yield WaitForEndOfFrame();
    
11.     // Create a texture the size of the screen, RGB24 format
    
12.     var width = Screen.width;
    
13.     var height = Screen.height;
    
14.     var tex = new Texture2D( width, height, TextureFormat.RGB24, false );
    
15.     // Read screen contents into the texture
    
16.     tex.ReadPixels( Rect(0, 0, width, height), 0, 0 );
    
17.     tex.Apply();
    
18.     // Encode texture into PNG
    
19.     var bytes = tex.EncodeToPNG();
    
20.     Destroy( tex );
    
21.     // Create a Web Form
    
22.     var form = new WWWForm();
    
23.     form.AddField("frameCount", Time.frameCount.ToString());
    
24.     form.AddBinaryData("fileUpload", bytes, "screenShot.png", "image/png");
    
25.     // Upload to a cgi script
    
26.     var w = WWW(screenShotURL, form);
    
27.     yield w;
    
28.     if (!String.IsNullOrEmpty(w.error))
    
29.         print(w.error);
    
30.     else
    
31.         print("Finished Uploading Screenshot");
    
32. }

复制代码

上面的代码段是用在unity程序中的：截取屏幕并生成png格式的流；访问服务器脚本，让改代码接收png格式的流。screenShotURL是wwwform访问的服务器脚本。