using UnityEngine;  
   
             using System.Collections; 
   
             public class DrawMesh : MonoBehaviour { 
   
                  GameObject gameobj; //绘制mesh的物体，如果是多个可以动态的生成      
   
                  public Camera cameraObj;   //NGUI中的摄像机     
   
                  public GameObject lookObject;//被指向的物体   
   
                  // Use this for initialization      
   
                  float x = 0;//屏幕的宽      
   
                  float y = 0;//屏蔽的高      
   
                  Color color;   
   
                  void Start () {          
   
                        color = Color.white;         
   
                        x = Screen.currentResolution.width;  //屏幕分辨率          
   
                        y = Screen.currentResolution.height;          
   
                       //这个地方我是动态获得的一个空的物体对象。用来创建三角形指示面片的。          
   
                       gameobj = (GameObject)Instantiate(Resources.Load("GameObject"));  
   
                }     
   
               // Update is called once per frame   
   
               void Update () {          
   
                      GetPositon();   
   
               } 
   
               //绘制三角面片      
   
               void DrawTrianglesEX(GameObject triangles, Vector3 port1, Vector3 port2, Vector3 port3, Color color)      
   
              {          
   
                    color.a = 0.8f;//面片的透明度          
   
                    if (triangles.GetComponent() == null)          
   
                   {             
   
                            triangles.AddComponent();  //添加MeshFilter             
   
                            triangles.AddComponent();//添加MeshRenderer              
   
                           //获得着色器              
   
                          triangles.renderer.material.shader = Shader.Find("Transparent/Diffuse");          
   
                   }  //Unity3D:www.unitymanual.com        
   
                  //实时改变颜色          
   
                  triangles.renderer.material.color = color;          
   
                  Mesh mesh = triangles.GetComponent().mesh;          
   
                  mesh.Clear(); 
   
                  //这个是主要的点的转换，在视窗位置转换成时间坐标位置。          
   
                  Vector3 v1 = triangles.transform.InverseTransformPoint(port1);          
   
                 Vector3 v2 = triangles.transform.InverseTransformPoint(Camera.main.ViewportToWorldPoint(port2));          
   
                 Vector3 v3 = triangles.transform.InverseTransformPoint(Camera.main.ViewportToWorldPoint(port3));          
   
                 mesh.vertices = new Vector3[] { v1, v2, v3 };          
   
                 mesh.triangles = new int[] { 0, 1, 2 };      
   
                } 
   
               //获得三个点的位置，并且转化为屏幕坐标      
   
              void GetPositon()     {          
   
                    Vector3 po = cameraObj.WorldToScreenPoint(transform.position);      
   
    　　　　　　//在这个地方是生算的，这边完全可以算出面板的宽与高。注意的是2D摄相机与主摄像机的关系。建议不要去生算。     
   
                    Vector3 po1 = new Vector3(po.x / x+0.075f, po.y / y, 1f);          
   
                    Vector3 po2 = po1 - new Vector3(0, 0.1f, 0);         
   
                    Vector3 v = lookObject.renderer.bounds.size;          
   
                    Vector3 equPosScreen = lookObject.transform.position+ new Vector3(0, v.y, 0);          
   
                    Vector3 po3 = equPosScreen;    
   
                    DrawTrianglesEX(gameobj, po3, po2, po1, color);      
   
               }  
   
            }