Unity角色蹲伏恢复高度卡顿问题求助

问题现象 #

• 角色蹲伏时高度过渡流畅，但松开左Ctrl恢复原高度时，静止状态下会出现明显卡顿
• 仅当角色移动时，蹲伏和恢复高度的双向过渡都能保持平滑
• 当前使用的蹲伏逻辑代码片段：

if (Input.GetKey(KeyCode.LeftControl))
{
    characterController.height = Mathf.Lerp(characterController.height, 0.5f, 10f * Time.deltaTime);
    canRun = false;
    canJump = false;
    walkingSpeed = 2f;
}

else
{
    characterController.height = Mathf.Lerp(characterController.height, 2.0f, 10f * Time.deltaTime);
    canRun = true;
    canJump = true;
    walkingSpeed = 4f;
}

问题原因 #

卡顿的核心原因是CharacterController的isGrounded检测机制：

• 当角色静止且处于蹲伏状态时，CharacterController底部几乎贴合地面，松开左Ctrl恢复高度时，isGrounded会瞬间从true变为false，重力瞬间作用产生向下位移，打断高度平滑过渡的视觉效果
• 角色移动时，CharacterController会持续检测地面并调整自身位置，抵消了重力带来的突兀位移，因此过渡看起来平滑

解决方案 #

方案1：调整CharacterController的Skin Width #

在Inspector面板中，给CharacterController的Skin Width设置一个较小的非零值（比如0.01）。这个参数会让CharacterController在碰撞检测时保留微小缓冲空间，避免恢复高度时isGrounded瞬间切换，减少重力带来的突兀位移。

方案2：恢复高度时临时抵消重力影响 #

修改Update中的蹲伏逻辑，在恢复高度过程中，针对静止状态临时抵消重力，直到高度恢复完成：

// 新增变量跟踪目标高度
private float targetHeight = 2.0f;

void Update()
{
    // ... 原有其他代码 ...

    // 蹲伏逻辑重构
    if (Input.GetKey(KeyCode.LeftControl))
    {
        targetHeight = 0.5f;
        canRun = false;
        canJump = false;
        walkingSpeed = 2f;
    }
    else
    {
        targetHeight = 2.0f;
        canRun = true;
        canJump = true;
        walkingSpeed = 4f;
    }

    // 平滑过渡高度
    characterController.height = Mathf.Lerp(characterController.height, targetHeight, 10f * Time.deltaTime);

    // 静止恢复高度时临时抵消重力
    if (targetHeight == 2.0f && Mathf.Abs(characterController.height - 2.0f) < 0.1f 
        && Mathf.Abs(moveDirection.x) < 0.1f && Mathf.Abs(moveDirection.z) < 0.1f)
    {
        moveDirection.y = 0;
    }
    else if (!characterController.isGrounded)
    {
        moveDirection.y -= gravity * Time.deltaTime;
    }

    // ... 原有其他代码 ...
}

方案3：调整Controller的Center偏移替代直接修改Height #

通过调整CharacterController的center而非直接修改height，可以避免碰撞检测异常，过渡更稳定：

private Vector3 originalCenter;
private const float originalHeight = 2.0f;
private const float crouchHeight = 0.5f;

void Start()
{
    characterController = GetComponent<CharacterController>();
    originalCenter = characterController.center;

    // ... 原有其他代码 ...
}

void Update()
{
    // ... 原有其他代码 ...

    if (Input.GetKey(KeyCode.LeftControl))
    {
        // 计算目标center偏移：高度减少量的一半向下偏移
        float targetY = originalCenter.y - (originalHeight - crouchHeight) / 2;
        characterController.center = Vector3.Lerp(characterController.center, new Vector3(0, targetY, 0), 10f * Time.deltaTime);
        characterController.height = Mathf.Lerp(characterController.height, crouchHeight, 10f * Time.deltaTime);
        canRun = false;
        canJump = false;
        walkingSpeed = 2f;
    }
    else
    {
        characterController.center = Vector3.Lerp(characterController.center, originalCenter, 10f * Time.deltaTime);
        characterController.height = Mathf.Lerp(characterController.height, originalHeight, 10f * Time.deltaTime);
        canRun = true;
        canJump = true;
        walkingSpeed = 4f;
    }

    // ... 原有其他代码 ...
}

完整修复后的FirstPersonController代码 #

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

[RequireComponent(typeof(CharacterController))]
public class FirstPersonController : MonoBehaviour
{
    public float walkingSpeed = 4f;
    public float runningSpeed = 5.5f;
    public float jumpSpeed = 4.0f;
    public float gravity = 15.0f;

    public Camera playerCamera;
    public CharacterController Player;

    public float lookSpeed = 2.0f;
    public float lookXLimit = 90.0f;

    public static bool canRun = true;
    public static bool running = false;
    
    CharacterController characterController;
    Vector3 moveDirection = Vector3.zero;
    float rotationX = 0;

    [HideInInspector]
    public bool canMove = true;
    public bool canJump = true;

    // 蹲伏相关变量
    private float targetHeight = 2.0f;
    private const float originalHeight = 2.0f;
    private const float crouchHeight = 0.5f;

    void Start()
    {
        characterController = GetComponent<CharacterController>();
        targetHeight = originalHeight;

        // Lock cursor
        Cursor.lockState = CursorLockMode.Locked;
        Cursor.visible = false;
    }

    void Update()
    {
        Vector3 forward = transform.TransformDirection(Vector3.forward);
        Vector3 right = transform.TransformDirection(Vector3.right);

        bool isRunning = Input.GetKey(KeyCode.LeftShift) && canRun == true;
        float curSpeedX = canMove ? (isRunning ? runningSpeed : walkingSpeed) * Input.GetAxis("Vertical") : 0;
        float curSpeedY = canMove ? (isRunning ? runningSpeed : walkingSpeed) * Input.GetAxis("Horizontal") : 0;
        float movementDirectionY = moveDirection.y;

        if (isRunning)
        {
            moveDirection = Vector3.ClampMagnitude((forward * curSpeedX) + (right * curSpeedY), 5.5f);
            running = true;
            if (Input.GetKey(KeyCode.W) || Input.GetKey(KeyCode.A) || Input.GetKey(KeyCode.S) || Input.GetKey(KeyCode.D))
            {
                Camera.main.fieldOfView = Mathf.Lerp(Camera.main.fieldOfView, 65f, 10f * Time.deltaTime);
            }
        }
        else
        {
            moveDirection = Vector3.ClampMagnitude((forward * curSpeedX) + (right * curSpeedY), 4.0f);
            running = false;
            Camera.main.fieldOfView = Mathf.Lerp(Camera.main.fieldOfView, 60f, 10f * Time.deltaTime);
        }

        if (Input.GetButton("Jump") && canMove && characterController.isGrounded && canJump)
        {
            moveDirection.y = jumpSpeed;
        }
        else
        {
            moveDirection.y = movementDirectionY;
        }

        // 蹲伏逻辑
        if (Input.GetKey(KeyCode.LeftControl))
        {
            targetHeight = crouchHeight;
            canRun = false;
            canJump = false;
            walkingSpeed = 2f;
        }
        else
        {
            targetHeight = originalHeight;
            canRun = true;
            canJump = true;
            walkingSpeed = 4f;
        }

        // 平滑过渡高度
        characterController.height = Mathf.Lerp(characterController.height, targetHeight, 10f * Time.deltaTime);

        // 静止恢复高度时临时抵消重力
        if (targetHeight == originalHeight && Mathf.Abs(characterController.height - originalHeight) < 0.1f 
            && Mathf.Abs(moveDirection.x) < 0.1f && Mathf.Abs(moveDirection.z) < 0.1f)
        {
            moveDirection.y = 0;
        }
        else if (!characterController.isGrounded)
        {
            moveDirection.y -= gravity * Time.deltaTime;
        }

        characterController.Move(moveDirection * Time.deltaTime);

        if (canMove)
        {
            rotationX += -Input.GetAxis("Mouse Y") * lookSpeed;
            rotationX = Mathf.Clamp(rotationX, -lookXLimit, lookXLimit);
            playerCamera.transform.localRotation = Quaternion.Euler(rotationX, 0, 0);
            transform.rotation *= Quaternion.Euler(0, Input.GetAxis("Mouse X") * lookSpeed, 0);   
        }
    }
}

内容的提问来源于stack exchange，提问作者lunixd