Unity) RayCast

 

RayCasting 이란?

 

레이저를 쏴서 오브젝트를 인식하는 시스템이다.

화면상에서 특정 오브젝트를 인식하기 위해 레이저를 쏴서 만나는 오브젝트들을 인식하여 활용하는 시스템으로 상당히 많은 물리연산을 동반하므로 유니티에서는 RaycastHit 이라는 함수를 제공하고 있다.

 

정적 변수

AllLayers	Layer mask constant to select all layers.
bounceThreshold	Two colliding objects with a relative velocity below this will not bounce (default 2). Must be positive.
defaultContactOffset	The default contact offset of the newly created colliders.
DefaultRaycastLayers	Layer mask constant to select default raycast layers.
gravity	The gravity applied to all rigid bodies in the scene.
IgnoreRaycastLayer	Layer mask constant to select ignore raycast layer.
queriesHitTriggers	Specifies whether queries (raycasts, spherecasts, overlap tests, etc.) hit Triggers by default.
sleepThreshold	The mass-normalized energy threshold, below which objects start going to sleep.
solverIterationCount	The default solver iteration count permitted for any rigid bodies (default 7). Must be positive.

정적 함수

BoxCast	Casts the box along a ray and returns detailed information on what was hit.
BoxCastAll	Like Physics.BoxCast, but returns all hits.
BoxCastNonAlloc	Cast the box along the direction, and store hits in the provided buffer.
CapsuleCast	Casts a capsule against all colliders in the scene and returns detailed information on what was hit.
CapsuleCastAll	Like Physics.CapsuleCast, but this function will return all hits the capsule sweep intersects.
CapsuleCastNonAlloc	Casts a capsule against all colliders in the scene and returns detailed information on what was hit into the buffer.
CheckBox	Check whether the given box overlaps with other colliders or not.
CheckCapsule	Checks if any colliders overlap a capsule-shaped volume in world space.
CheckSphere	Returns true if there are any colliders overlapping the sphere defined by position and radius in world coordinates.
GetIgnoreLayerCollision	Are collisions between layer1 and layer2 being ignored?
IgnoreCollision	Makes the collision detection system ignore all collisions between collider1 and collider2.
IgnoreLayerCollision	Makes the collision detection system ignore all collisions between any collider in layer1 and any collider in layer2.Note that IgnoreLayerCollision will reset the trigger state of affected colliders, so you might receive OnTriggerExit and OnTriggerEnter messages in response to calling this.
Linecast	Returns true if there is any collider intersecting the line between start and end.
OverlapBox	Find all colliders touching or inside of the given box.
OverlapBoxNonAlloc	Find all colliders touching or inside of the given box, and store them into the buffer.
OverlapSphere	Returns an array with all colliders touching or inside the sphere.
OverlapSphereNonAlloc	Computes and stores colliders touching or inside the sphere into the provided buffer.
Raycast	Casts a ray, from point origin, in direction direction, of length maxDistance, against all colliders in the scene.
RaycastAll	Casts a ray through the scene and returns all hits. Note that order is not guaranteed.
RaycastNonAlloc	Cast a ray through the scene and store the hits into the buffer.
SphereCast	Casts a sphere along a ray and returns detailed information on what was hit.
SphereCastAll	Like Physics.SphereCast, but this function will return all hits the sphere sweep intersects.
SphereCastNonAlloc	Cast sphere along the direction and store the results into buffer.

위 표처럼 수많은 도구들이 존재하는데 몇가지만 잘 사용해도 우리가 원하는 효과를 대부분 구현할 수 있다고 한다.

 

 

실제로 총을 발사하는 과정을 구현해보았다.

효과를 위한 Prefab들이 몇가지 필요하긴 하지만 손쉽게 구현할 수 있었다.

 

 

#관련코드

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Weapon : MonoBehaviour
{
    [SerializeField] Camera FPCamera;
    [SerializeField] float range = 100f;
    [SerializeField] float damage = 30f;
    [SerializeField] ParticleSystem muzzleFlash;
    [SerializeField] GameObject hitEffect;

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

    private void Shoot()
    {
        PlayMuzzleFlash();
        ProcessRaycast();
    }

    private void PlayMuzzleFlash()
    {
        muzzleFlash.Play();
    }

    private void ProcessRaycast()
    {
        RaycastHit hit;
        if (Physics.Raycast(FPCamera.transform.position, FPCamera.transform.forward, out hit, range))
        {
            CreateHitImpact(hit);
            Enemy_Health target = hit.transform.GetComponent<Enemy_Health>();
            if (target == null) return;
            target.TakeDamage(damage);
        }
        else
        {
            return;
        }
    }

    private void CreateHitImpact(RaycastHit hit)
    {
        GameObject impact = Instantiate(hitEffect, hit.point, Quaternion.LookRotation(hit.normal));
        Destroy(impact, 0.1f);
    }
}

 

#기타

 

위 코드에서 RaycastHit.point과 RaycastHit.normal을 사용했는데 모두 RaycastHit 함수의 프로퍼티들이다.

(1) collider

ray가 충돌한 충돌체(Collider) 이다.

 

(2) point

Collider와 충돌한 지점이다.

 

(3) normal

충돌한 지점에서 면에 수직인 법선벡터이다.

법선벡터의 길이는 1이다.

우리가 충돌한 지점을 바라보는 방향에 수직인 방향이므로 효과를 생성할때 참고한다.

 

(4) distance

ray의 origin으로부터 충돌한 지점까지의 거리이다./

 

(5) transform

충돌체의 Transform 컴포넌트이다.

 

(6) rigidbody

충돌체의 RigidBody 컴포넌트이다.

 

사실 Raycast 를 위해 어떠한 물리연산을 사용했는지도 궁금해서 기회가 된다면 좀 더 상세히 다뤄보려고 한다. 

 

 

#참조

https://docs.unity3d.com/ScriptReference/Physics.Raycast.html

Unity - Scripting API: Physics.Raycast

https://coding-of-today.tistory.com/175

[유니티] 레이캐스트 총정리 - Unity Raycast

https://m.blog.naver.com/happybaby56/221370502930

[유니티] RaycastHit 구조체