3D CharacterController 이동, 카메라 기준 방향 변환 및 경사면(Slope) 제어

using UnityEngine;

[RequireComponent(typeof(CharacterController))]
public class PlayerController3D : MonoBehaviour
{
    [Header("이동 및 회전")]
    [SerializeField] private float walkSpeed = 6f;
    [SerializeField] private float runSpeed = 10f;
    [SerializeField] private float rotationSmoothTime = 0.08f;

    [Header("중력 및 점프")]
    [SerializeField] private float gravity = -20f;
    [SerializeField] private float jumpHeight = 1.8f;
    [SerializeField] private float groundedGravity = -2f;

    [Header("경사면 접지")]
    [SerializeField] private float slopeRayLength = 1.2f;

    private CharacterController _controller;
    private Transform _camTransform;
    private float _verticalVelocity;
    private float _currentRotationVelocity;

    private void Awake()
    {
        _controller = GetComponent<CharacterController>();
        if (Camera.main != null) _camTransform = Camera.main.transform;
    }

    private void Update()
    {
        // 1. 카메라 기준 입력 변환
        float h = Input.GetAxisRaw("Horizontal");
        float v = Input.GetAxisRaw("Vertical");
        Vector3 inputDir = new Vector3(h, 0f, v).normalized;

        Vector3 moveDir = Vector3.zero;

        if (inputDir.magnitude > 0.01f && _camTransform != null)
        {
            // 카메라 Y 회전각을 더해 이동 방향 회전
            float targetAngle = Mathf.Atan2(inputDir.x, inputDir.z) * Mathf.Rad2Deg + _camTransform.eulerAngles.y;
            float angle = Mathf.SmoothDampAngle(transform.eulerAngles.y, targetAngle, ref _currentRotationVelocity, rotationSmoothTime);
            transform.rotation = Quaternion.Euler(0f, angle, 0f);

            moveDir = Quaternion.Euler(0f, targetAngle, 0f) * Vector3.forward;
        }

        // 2. 경사면 보정 벡터 계산
        if (OnSlope(out Vector3 slopeNormal))
        {
            // 경사면 평면에 평행하게 이동 벡터 투영
            moveDir = Vector3.ProjectOnPlane(moveDir, slopeNormal).normalized;
        }

        // 3. 중력 및 점프 처리
        bool isGrounded = _controller.isGrounded;

        if (isGrounded)
        {
            _verticalVelocity = groundedGravity;

            if (Input.GetButtonDown("Jump"))
            {
                _verticalVelocity = Mathf.Sqrt(jumpHeight * -2f * gravity);
            }
        }
        else
        {
            _verticalVelocity += gravity * Time.deltaTime;
        }

        // 4. 최종 이동 적용
        float currentSpeed = Input.GetKey(KeyCode.LeftShift) ? runSpeed : walkSpeed;
        Vector3 finalMotion = (moveDir * currentSpeed) + (Vector3.up * _verticalVelocity);

        _controller.Move(finalMotion * Time.deltaTime);
    }

    private bool OnSlope(out Vector3 hitNormal)
    {
        hitNormal = Vector3.up;
        if (!_controller.isGrounded) return false;

        if (Physics.Raycast(transform.position, Vector3.down, out RaycastHit hit, slopeRayLength))
        {
            hitNormal = hit.normal;
            float angle = Vector3.Angle(Vector3.up, hitNormal);
            // 경사각이 0보다 크고 최대 등반각보다 작은지 검사
            return angle > 0f && angle <= _controller.slopeLimit;
        }
        return false;
    }
}