untiy Physics2D.GetRayIntersectionNonAlloc 介绍

原创于 2025-07-18 10:13:36 发布 · 385 阅读

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Physics2D.GetRayIntersectionNonAlloc 是 Unity 中一个用于 2D 物理射线检测的高性能方法。它可以检测射线与 2D 碰撞器的交点，但不会分配新的内存（非分配版本）。

方法签名

public static int GetRayIntersectionNonAlloc(Ray ray, RaycastHit2D[] results, float distance = Mathf.Infinity, int layerMask = DefaultRaycastLayers)

参数说明

ray: 要投射的射线（Ray对象）
results: 用于存储结果的 RaycastHit2D 数组（需要预先分配）
distance: 射线的最大距离（可选，默认为无限远）
layerMask: 层级掩码，指定要检测的层级（可选）

返回值

返回检测到的碰撞数量（int类型）

使用示例

using UnityEngine;

public class RaycastExample : MonoBehaviour
{
    // 预分配结果数组，避免运行时分配内存
    private RaycastHit2D[] raycastResults = new RaycastHit2D[10];
    
    void Update()
    {
        // 创建从鼠标位置向右的射线
        Vector3 mousePos = Camera.main.ScreenToWorldPoint(Input.mousePosition);
        mousePos.z = 0f;
        
        Ray ray = new Ray(mousePos, Vector2.right);
        
        // 执行射线检测
        int hitCount = Physics2D.GetRayIntersectionNonAlloc(
            ray, 
            raycastResults, 
            10f,  // 最大距离
            LayerMask.GetMask("Default", "Enemy")  // 只检测特定层级
        );
        
        // 处理检测结果
        for (int i = 0; i < hitCount; i++)
        {
            RaycastHit2D hit = raycastResults[i];
            Debug.Log($"击中物体: {hit.collider.name}, 距离: {hit.distance}");
            
            // 在击中点绘制标记
            Debug.DrawLine(ray.origin, hit.point, Color.red, 0.1f);
        }
        
        // 绘制射线
        Debug.DrawRay(ray.origin, ray.direction * 10f, Color.blue, 0.1f);
    }
}

实际应用场景

1. 激光武器系统

public class LaserWeapon : MonoBehaviour
{
    [SerializeField] private LineRenderer laserLine;
    [SerializeField] private LayerMask targetLayers;
    [SerializeField] private float maxRange = 50f;
    
    private RaycastHit2D[] hits = new RaycastHit2D[5];
    
    void Update()
    {
        FireLaser();
    }
    
    void FireLaser()
    {
        Ray ray = new Ray(transform.position, transform.right);
        int hitCount = Physics2D.GetRayIntersectionNonAlloc(ray, hits, maxRange, targetLayers);
        
        Vector3 endPoint = transform.position + transform.right * maxRange;
        
        if (hitCount > 0)
        {
            // 使用最近的击中点
            RaycastHit2D closestHit = hits[0];
            for (int i = 1; i < hitCount; i++)
            {
                if (hits[i].distance < closestHit.distance)
                    closestHit = hits[i];
            }
            
            endPoint = closestHit.point;
            
            // 对击中的目标造成伤害
            if (closestHit.collider.TryGetComponent<IDamageable>(out var target))
            {
                target.TakeDamage(10f);
            }
        }
        
        // 更新激光线渲染
        laserLine.SetPosition(0, transform.position);
        laserLine.SetPosition(1, endPoint);
    }
}

2. 视线检测系统

public class VisionSystem : MonoBehaviour
{
    [SerializeField] private LayerMask obstacleLayers;
    [SerializeField] private LayerMask targetLayers;
    
    private RaycastHit2D[] visionHits = new RaycastHit2D[10];
    
    public bool CanSeeTarget(Transform target)
    {
        Vector2 direction = (target.position - transform.position).normalized;
        float distance = Vector2.Distance(transform.position, target.position);
        
        Ray ray = new Ray(transform.position, direction);
        int hitCount = Physics2D.GetRayIntersectionNonAlloc(ray, visionHits, distance, obstacleLayers | targetLayers);
        
        for (int i = 0; i < hitCount; i++)
        {
            // 如果先击中障碍物，则视线被阻挡
            if (((1 << visionHits[i].collider.gameObject.layer) & obstacleLayers) != 0)
            {
                return false;
            }
            
            // 如果击中目标且没有障碍物阻挡
            if (visionHits[i].collider.transform == target)
            {
                return true;
            }
        }
        
        return false;
    }
}