判斷對象是否在視野内,有兩種方式:
第一種:
- 不設定固定的目标,
- 使用LayerMask,設定尋找對象的Layer,
- 使用Physics.OverlapSphere方法,以給定的位置為圓心,按照設定距離投射一個球體,傳回與投射的球體相交的碰撞器。
第二種:
- 設定固定的目标,
- 計算目前對象與目标對象的距離direction.magnitude小于設定視野距離,
- 計算目前對象的位置到目标點的方向與目前對象的前進方向的夾角Vector3.Angle(direction, transform.forward)小于設定視野角度,
- 使用Physics.Linecast,如果有任何碰撞器與起始點與終點之間的射線相交,傳回true。如果在視野内,傳回目标對象。
using UnityEngine;
public class CanSeeObjectScript : MonoBehaviour
{
public Transform targetObject;
public Vector3 positionOffset;
public LayerMask objectLayerMask;
private Transform objectInSight;
public float fieldOfViewAngle;
public float viewDistance;
private void Update()
{
if (CanSeeObject())
{
Debug.Log("找到目标");
}
else
{
Debug.Log("沒有找到目标");
}
}
private bool CanSeeObject()
{
if (targetObject == null)
{
// 如果目标對象為空,按照設定距離投射一個球體,檢查在視野内與投射的球體相交的碰撞器
objectInSight = WithinSight(transform, positionOffset, fieldOfViewAngle, viewDistance, objectLayerMask);
}
else
{
// 如果目标對象不為空,則确定目标對象在視野内
objectInSight = WithinSight(transform, positionOffset, fieldOfViewAngle, viewDistance, targetObject);
}
if (objectInSight != null)
{
return true;
}
return false;
}
public static Transform WithinSight(Transform transform, Vector3 positionOffset, float fieldOfViewAngle, float viewDistance, LayerMask objectLayerMask)
{
Transform objectFound = null;
// Physics.OverlapSphere 檢測場景中與投射的球體相交的碰撞器
var hitColliders = Physics.OverlapSphere(transform.position, viewDistance, objectLayerMask);
if (hitColliders != null)
{
float minAngle = Mathf.Infinity;
for (int i = 0; i < hitColliders.Length; ++i)
{
float angle;
Transform obj;
if ((obj = WithinSight(transform, positionOffset, fieldOfViewAngle, viewDistance, hitColliders[i].transform, false, out angle)) != null)
{
// 這個對象在視野内,并且角度小于任何其他的對象,設定位于目前對象最前面的對象到objectFound
if (angle < minAngle)
{
minAngle = angle;
objectFound = obj;
}
}
}
}
return objectFound;
}
public static Transform WithinSight(Transform transform, Vector3 positionOffset, float fieldOfViewAngle, float viewDistance, Transform targetObject)
{
float angle;
return WithinSight(transform, positionOffset, fieldOfViewAngle, viewDistance, targetObject, false, out angle);
}
private static Transform WithinSight(Transform transform, Vector3 positionOffset, float fieldOfViewAngle, float viewDistance, Transform targetObject, bool usePhysics2D, out float angle)
{
// 計算目前對象的位置到目标點的方向
var direction = targetObject.position - (transform.position + positionOffset);
// 計算目前對象的位置到目标點的方向與目前對象的前進方向的夾角
angle = Vector3.Angle(direction, transform.forward);
if (direction.magnitude < viewDistance && angle < fieldOfViewAngle * 0.5f)
{
// 目标對象需要在目前對象的視野内
if (LineOfSight(transform, positionOffset, targetObject, usePhysics2D) != null)
{
//如果在視野内,傳回目标對象
return targetObject;
}
else if (targetObject.GetComponent<Collider>() == null)
{
// 如果linecast沒有碰撞到任何對象,并且目标對象沒有collider,沒有什麼阻礙
if (targetObject.gameObject.activeSelf)
return targetObject;
}
}
// 如果目标對象沒有在視野内,傳回空
return null;
}
public static Transform LineOfSight(Transform transform, Vector3 positionOffset, Transform targetObject, bool usePhysics2D)
{
RaycastHit hit;
// transform.TransformPoint方法,在原來位置的基礎上加上偏移位置
// Physics.Linecast 如果有任何碰撞器與起始點與終點之間的射線相交,傳回true
if (Physics.Linecast(transform.TransformPoint(positionOffset), targetObject.position, out hit))
{
if (hit.transform.Equals(targetObject))
{
//如果在視野内,傳回目标對象
return targetObject;
}
}
return null;
}
}