摄像机分为两种，一种是正交摄像机还有一种是透视摄像机。正交摄像机无论远近它的视口范围永远是固定的，但是透视摄像机是由原点向外扩散性发射，也就是距离越远它的视口区域也就越大。那么我们如何获取距离摄像机任意距离的视口区域呢？如下图所示，分别用红色和黄色两种颜色将计算出来的视口区域标记了出来。
下面上代码，把如下脚本挂在摄像机出直接运行游戏即可看到。
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using UnityEngine;
using System.Collections;
public class CameraView : MonoBehaviour {
private Camera theCamera;
//距离摄像机8.5米 用黄色表示
public float upperDistance = 8.5f;
//距离摄像机12米 用红色表示
public float lowerDistance = 12.0f;
private Transform tx;
void Start (){
if ( !theCamera )
{
theCamera = Camera.main;
}
tx = theCamera.transform;
}
void Update (){
FindUpperCorners();
FindLowerCorners();
}
void FindUpperCorners (){
Vector3[] corners = GetCorners( upperDistance );
// for debugging
Debug.DrawLine( corners[0], corners[1], Color.yellow ); // UpperLeft -> UpperRight
Debug.DrawLine( corners[1], corners[3], Color.yellow ); // UpperRight -> LowerRight
Debug.DrawLine( corners[3], corners[2], Color.yellow ); // LowerRight -> LowerLeft
Debug.DrawLine( corners[2], corners[0], Color.yellow ); // LowerLeft -> UpperLeft
}
void FindLowerCorners (){
Vector3[] corners = GetCorners( lowerDistance );
// for debugging
Debug.DrawLine( corners[0], corners[1], Color.red );
Debug.DrawLine( corners[1], corners[3], Color.red );
Debug.DrawLine( corners[3], corners[2], Color.red );
Debug.DrawLine( corners[2], corners[0], Color.red );
}
Vector3[] GetCorners ( float distance ){
Vector3[] corners = new Vector3[ 4 ];
float halfFOV = ( theCamera.fieldOfView * 0.5f ) * Mathf.Deg2Rad;
float aspect = theCamera.aspect;
float height = distance * Mathf.Tan( halfFOV );
float width = height * aspect;
// UpperLeft
corners[ 0 ] = tx.position - ( tx.right * width );
corners[ 0 ] += tx.up * height;
corners[ 0 ] += tx.forward * distance;
// UpperRight
corners[ 1 ] = tx.position + ( tx.right * width );
corners[ 1 ] += tx.up * height;
corners[ 1 ] += tx.forward * distance;
// LowerLeft
corners[ 2 ] = tx.position - ( tx.right * width );
corners[ 2 ] -= tx.up * height;
corners[ 2 ] += tx.forward * distance;
// LowerRight
corners[ 3 ] = tx.position + ( tx.right * width );
corners[ 3 ] -= tx.up * height;
corners[ 3 ] += tx.forward * distance;
return corners;
}
}
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这个脚本是我在逛国外网站无意间发现的，我这里翻译成了C#语言。http://answers.unity3d.com/questions/509466/scale-box-collider-to-camera-view-1.html?sort=oldest
我们可以根据文章里的算法计算出视口3D的坐标点，有了坐标信息那么想干什么都好干了，呵呵。
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