Unity获取摄像机在某个平面上的视野范围

这是已知平面上的一个点和平面的法线的情况下，求摄像机在平面看到的视野范围，下图绿色的框框就是了。

效果:

代码：

  1 using UnityEngine;
  2 using System.Collections;
  3 using System;
  4
  5 public class CameraPlaneView : MonoBehaviour
  6 {
  7     #region for debug
  8     public Camera viewCamera;
  9
 10     void Update()
 11     {
 12         Vector3[] corners;
 13         if(GetPlaneCorners(Vector3.up, Vector3.zero, viewCamera, out corners))
 14         {
 15             Debug.DrawLine(corners[0], corners[1], Color.green);    // bottom
 16             Debug.DrawLine(corners[1], corners[2], Color.green);    // right
 17             Debug.DrawLine(corners[2], corners[3], Color.green);    // top
 18             Debug.DrawLine(corners[3], corners[0], Color.green);    // left
 19         }
 20     }
 21     #endregion
 22
 23
 24     /// <summary>
 25     /// 获取摄像机在平面上的视野范围的4个角的顶点
 26     /// </summary>
 27     /// <param name="normal">平面法线</param>
 28     /// <param name="planePoint">平面上的一点</param>
 29     /// <param name="camera">摄像机</param>
 30     /// <param name="corners">返回4个角的顺序：左下、右下、右上、左上</param>
 31     /// <returns>摄像机与平面是否完全相交</returns>
 32     public static bool GetPlaneCorners(Vector3 normal, Vector3 planePoint,Camera camera, out Vector3[] corners)
 33     {
 34         Plane plane = new Plane(normal, planePoint);
 35         return GetPlaneCorners(ref plane, camera, out corners);
 36     }
 37
 38     /// <summary>
 39     /// 获取摄像机在平面上的视野范围的4个角的顶点
 40     /// </summary>
 41     /// <param name="plane">平面结构体</param>
 42     /// <param name="camera">摄像机</param>
 43     /// <param name="corners">返回4个角的顺序：左下、右下、右上、左上</param>
 44     /// <returns>摄像机与平面是否完全相交</returns>
 45     public static bool GetPlaneCorners(ref Plane plane, Camera camera, out Vector3[] corners)
 46     {
 47         Ray rayBL = camera.ViewportPointToRay(new Vector3(0, 0, 1));     // bottom left
 48         Ray rayBR = camera.ViewportPointToRay(new Vector3(1, 0, 1));     // bottom right
 49         Ray rayTL = camera.ViewportPointToRay(new Vector3(0, 1, 1));     // top left
 50         Ray rayTR = camera.ViewportPointToRay(new Vector3(1, 1, 1));     // top right
 51
 52         corners = new Vector3[4];
 53         if (!GetRayPlaneIntersection(ref plane, rayBL, out corners[0])
 54             || !GetRayPlaneIntersection(ref plane, rayBR, out corners[1])
 55             || !GetRayPlaneIntersection(ref plane, rayTR, out corners[2])
 56             || !GetRayPlaneIntersection(ref plane, rayTL, out corners[3]))
 57         {
 58             return false;
 59         }
 60         else
 61         {
 62             return true;
 63         }
 64     }
 65
 66     /// <summary>
 67     /// 获取平面与射线的交点
 68     /// </summary>
 69     /// <param name="plane">平面结构体</param>
 70     /// <param name="ray">射线</param>
 71     /// <param name="intersection">返回交点</param>
 72     /// <returns>是否相交</returns>
 73     public static bool GetRayPlaneIntersection(ref Plane plane, Ray ray, out Vector3 intersection)
 74     {
 75         float enter;
 76         if(!plane.Raycast(ray, out enter))
 77         {
 78             intersection = Vector3.zero;
 79             return false;
 80         }
 81
 82         // 下面是获取t的公式
 83         // 注意，你需要先判断射线与平面是否平行，如果平面和射线平行，那么平面法线和射线方向的点积为0，即除数为0.
 84         //float t = (Vector3.Dot(normal, planePoint) - Vector3.Dot(normal, ray.origin)) / Vector3.Dot(normal, ray.direction.normalized);
 85         if (enter >= 0)
 86         {
 87             intersection = ray.origin + enter * ray.direction.normalized;
 88             return true;
 89         }
 90         else
 91         {
 92             intersection = Vector3.zero;
 93             return false;
 94         }
 95     }
 96
 97     /// <summary>
 98     /// 获取平面与射线的交点
 99     /// </summary>
100     /// <param name="normal">平面法线</param>
101     /// <param name="planePoint">平面上的一点</param>
102     /// <param name="ray">射线</param>
103     /// <param name="intersection">返回交点</param>
104     /// <returns>是否相交</returns>
105     public static bool GetRayPlaneIntersection(Vector3 normal, Vector3 planePoint, Ray ray, out Vector3 intersection)
106     {
107         Plane plane = new Plane(normal, planePoint);
108         return GetRayPlaneIntersection(ref plane, ray, out intersection);
109     }
110 }