Raycasting

using UnityEngine;

public class HitscanGun : MonoBehaviour
{
  public float range = 50f;
  public int damage = 25;
  public LayerMask shootMask;
  public ParticleSystem muzzleFlash;

  Camera cam;
  RaycastHit hit; // Khai báo ngoài để tránh GC

  void Start() => cam = Camera.main;

  void Update()
  {
      if (Input.GetButtonDown("Fire1")) Fire();
  }

  void Fire()
  {
      muzzleFlash.Play();

      // Bắn ray từ tâm camera về phía trước
      if (Physics.Raycast(cam.transform.position,
                         cam.transform.forward,
                         out hit, range, shootMask))
      {
          Debug.Log("Bắn trúng: " + hit.collider.name +
                     " cách " + hit.distance.ToString("F1") + "m");

          hit.collider.GetComponent<Health>()
             ?.TakeDamage(damage);
      }
  }
}

using UnityEngine;

public class RaycastUtils : MonoBehaviour
{
  [Header("Ground Check")]
  public float groundCheckDist = 1.2f;
  public LayerMask groundLayer;
  bool isGrounded;

  [Header("Mouse Picking")]
  public LayerMask clickable;

  Camera cam;
  RaycastHit hit;

  void Awake() => cam = Camera.main;

  void Update()
  {
      // Ground check mỗi frame — SphereCast mịn hơn Raycast
      isGrounded = Physics.SphereCast(
          transform.position, 0.4f,
          Vector3.down, out hit,
          groundCheckDist, groundLayer
      );

      // Click chuột → chuyển sang toạ độ 3D
      if (Input.GetMouseButtonDown(0))
      {
          Ray ray = cam.ScreenPointToRay(Input.mousePosition);
          if (Physics.Raycast(ray, out hit, 100f, clickable))
          {
              Debug.Log("Click vào: " + hit.collider.name);
              // Di chuyển nhân vật đến hit.point
              MoveTo(hit.point);
          }
      }
  }

  void OnDrawGizmosSelected()
  {
      Gizmos.color = isGrounded ? Color.green : Color.red;
      Gizmos.DrawLine(transform.position,
          transform.position + Vector3.down * groundCheckDist);
  }
}