2D 플랫포머 캐릭터 이동과 코요테 타임(Coyote Time) · 점프 버퍼링

using UnityEngine;

[RequireComponent(typeof(Rigidbody2D), typeof(Collider2D))]
public class PlatformerController2D : MonoBehaviour
{
    [Header("이동 설정")]
    [SerializeField] private float moveSpeed = 9f;
    [SerializeField] private float acceleration = 50f;
    [SerializeField] private float deceleration = 60f;

    [Header("점프 & 조작 보정")]
    [SerializeField] private float jumpForce = 14f;
    [SerializeField] private float coyoteTimeDuration = 0.12f;
    [SerializeField] private float jumpBufferDuration = 0.1f;
    [SerializeField] private float fallMultiplier = 2.5f;
    [SerializeField] private float lowJumpMultiplier = 2.0f;

    [Header("지면 판정")]
    [SerializeField] private Transform groundCheckPoint;
    [SerializeField] private Vector2 groundCheckSize = new Vector2(0.6f, 0.1f);
    [SerializeField] private LayerMask groundLayer;

    private Rigidbody2D _rb;
    private float _horizontalInput;
    private float _coyoteTimeCounter;
    private float _jumpBufferCounter;
    private bool _isGrounded;

    private void Awake()
    {
        _rb = GetComponent<Rigidbody2D>();
    }

    private void Update()
    {
        // 입력 수집
        _horizontalInput = Input.GetAxisRaw("Horizontal");

        // 지면 판정
        _isGrounded = Physics2D.OverlapBox(groundCheckPoint.position, groundCheckSize, 0f, groundLayer);

        // 코요테 타임 카운터
        if (_isGrounded)
            _coyoteTimeCounter = coyoteTimeDuration;
        else
            _coyoteTimeCounter -= Time.deltaTime;

        // 점프 버퍼링 카운터
        if (Input.GetButtonDown("Jump"))
            _jumpBufferCounter = jumpBufferDuration;
        else
            _jumpBufferCounter -= Time.deltaTime;

        // 점프 실행 조건
        if (_jumpBufferCounter > 0f && _coyoteTimeCounter > 0f)
        {
            ExecuteJump();
        }

        // 가변 점프 높이: 버튼을 일찍 떼면 중력 증가
        ApplyJumpGravityModifiers();
    }

    private void FixedUpdate()
    {
        ApplyHorizontalMovement();
    }

    private void ExecuteJump()
    {
        // Unity 6 linearVelocity (구버전 velocity)
        _rb.linearVelocity = new Vector2(_rb.linearVelocity.x, jumpForce);
        _jumpBufferCounter = 0f;
        _coyoteTimeCounter = 0f;
    }

    private void ApplyHorizontalMovement()
    {
        float targetSpeed = _horizontalInput * moveSpeed;
        float speedDiff = targetSpeed - _rb.linearVelocity.x;
        float accelRate = (Mathf.Abs(targetSpeed) > 0.01f) ? acceleration : deceleration;
        float movement = speedDiff * accelRate * Time.fixedDeltaTime;

        _rb.linearVelocity = new Vector2(_rb.linearVelocity.x + movement, _rb.linearVelocity.y);
    }

    private void ApplyJumpGravityModifiers()
    {
        if (_rb.linearVelocity.y < 0f)
        {
            // 하강 시 더 빠른 속도로 떨어져 묵직한 조작감 제공
            _rb.gravityScale = fallMultiplier;
        }
        else if (_rb.linearVelocity.y > 0f && !Input.GetButton("Jump"))
        {
            // 점프 키를 살짝 탭했을 때 낮은 점프
            _rb.gravityScale = lowJumpMultiplier;
        }
        else
        {
            _rb.gravityScale = 1f;
        }
    }

    private void OnDrawGizmosSelected()
    {
        if (groundCheckPoint == null) return;
        Gizmos.color = Color.green;
        Gizmos.DrawWireCube(groundCheckPoint.position, groundCheckSize);
    }
}