Unity斜坡移动脚本故障：角色穿透Ground层斜坡问题

已将场景内所有斜坡的Layer设置为Ground，同时把斜坡检测器的目标检测Layer也设为Ground，预期触发斜坡专属移动逻辑，让角色正常上下斜坡。但使用《Rigidbody FPS Controller Tutorial #3 | Slope Handling + FIXES!》中的PlayerMovement脚本后，角色直接穿透斜坡掉落，无法定位问题。

使用的代码如下：

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

public class PlayerMovement : MonoBehaviour
{
    float playerHeight = 2f;

    [SerializeField] Transform orientation;

    [Header("Movement")]
    public float moveSpeed = 6f;
    public float movementMultiplier = 10f;
    [SerializeField] float airMultiplier = 0.4f;


    [Header("Keybinds")]
    [SerializeField] KeyCode jumpKey = KeyCode.Space;

    [Header("Jumping")]
    public float jumpForce = 5f;

    [Header("Drag")]
    float groundDrag = 6f;
    float airDrag = 2f;

    float rbDrag = 6f;

    float horizontalMovement;
    float verticalMovement;

    [Header("Ground Detection")]
    [SerializeField] LayerMask groundMask;
    bool isGrounded;
    float groundDistance = 0.4f;
     

    Vector3 moveDirection;
    Vector3 slopeMoveDirection;

    Rigidbody rb;

    RaycastHit slopeHit;
    private bool OnSlope()
    {
        if (Physics.Raycast(transform.position, Vector3.down, out slopeHit, playerHeight /2 + 0.5f))
        {
            if (slopeHit.normal != Vector3.up)
            {
                return true;
            }
            else
            {
                return false;
            }
        }
        return false;
    }

    private void Start()
    {
        rb = GetComponent<Rigidbody>();
        rb.freezeRotation = true;
    }

    private void Update()
    {
        isGrounded = Physics.CheckSphere(transform.position - new Vector3(0, 1, 0), groundDistance, groundMask);

        MyInput();
        ControlDrag();

        if (Input.GetKeyDown(jumpKey) && isGrounded)
        {
            Jump();
        }

        slopeMoveDirection = Vector3.ProjectOnPlane(moveDirection, slopeHit.normal);
    }

    void MyInput()
    {
        horizontalMovement = Input.GetAxisRaw("Horizontal");
        verticalMovement = Input.GetAxisRaw("Vertical");

        moveDirection = orientation.forward * verticalMovement + orientation.right * horizontalMovement;
    }

    void Jump()
    {
        rb.AddForce(transform.up * jumpForce, ForceMode.Impulse);
    }

    void ControlDrag()
    {
        if (isGrounded)
        {
            rb.drag = groundDrag;
        }
        else
        {
            rb.drag = airDrag;
        }
    }

    private void FixedUpdate()
    {
        MovePlayer();
    }

    void MovePlayer()
    {
        if (isGrounded && !OnSlope())
        {
            rb.AddForce(moveDirection.normalized * moveSpeed * movementMultiplier, ForceMode.Acceleration);
        }
        else if (isGrounded && OnSlope())
        {
            rb.AddForce(slopeMoveDirection.normalized * moveSpeed * movementMultiplier, ForceMode.Acceleration);
        }
        else if (!isGrounded)
        {
            rb.AddForce(moveDirection.normalized * moveSpeed * movementMultiplier * airMultiplier, ForceMode.Acceleration);
        }

    }
}

1. 地面检测Sphere位置偏移问题 #

代码中isGrounded的检测Sphere位置是transform.position - new Vector3(0,1,0)，若角色碰撞体中心与transform.position不重合（比如胶囊体碰撞体中心偏移），会导致检测点未触碰到斜坡，isGrounded误判为false，角色进入空中移动逻辑进而穿透斜坡。

• 修复：将检测位置改为角色碰撞体底部，比如：

  isGrounded = Physics.CheckSphere(transform.position - new Vector3(0, playerHeight/2, 0), groundDistance, groundMask);
  

2. 斜坡检测Raycast长度不足 #

OnSlope()中Raycast长度为playerHeight/2 +0.5f（1.5f），若斜坡碰撞体位置较低或角色碰撞体较大，可能无法检测到斜坡，导致OnSlope()返回false，走平地移动逻辑穿透斜坡。

• 修复：调整Raycast长度为playerHeight/2 + groundDistance，确保覆盖地面检测范围：

  if (Physics.Raycast(transform.position, Vector3.down, out slopeHit, playerHeight /2 + groundDistance))
  

3. 斜坡移动方向计算时机错误 #

当前slopeMoveDirection在Update()中计算，但OnSlope()未提前更新slopeHit数据，可能使用旧的法线计算方向；且MovePlayer()中重复调用OnSlope()会导致数据不一致。

• 修复：在Update()中先更新斜坡检测数据，再计算移动方向，避免重复Raycast：

  // 类内新增变量
  bool onSlope;
  
  private void Update()
  {
      isGrounded = Physics.CheckSphere(transform.position - new Vector3(0, playerHeight/2, 0), groundDistance, groundMask);
      onSlope = OnSlope(); // 先更新slopeHit数据
  
      MyInput();
      ControlDrag();
  
      if (Input.GetKeyDown(jumpKey) && isGrounded)
      {
          Jump();
      }
  
      slopeMoveDirection = Vector3.ProjectOnPlane(moveDirection, slopeHit.normal);
  }
  
  void MovePlayer()
  {
      if (isGrounded && !onSlope)
      {
          rb.AddForce(moveDirection.normalized * moveSpeed * movementMultiplier, ForceMode.Acceleration);
      }
      else if (isGrounded && onSlope)
      {
          rb.AddForce(slopeMoveDirection.normalized * moveSpeed * movementMultiplier, ForceMode.Acceleration);
      }
      else if (!isGrounded)
      {
          rb.AddForce(moveDirection.normalized * moveSpeed * movementMultiplier * airMultiplier, ForceMode.Acceleration);
      }
  }
  

4. Rigidbody碰撞设置问题 #

检查角色Rigidbody组件：

• 将Collision Detection设为Continuous或Continuous Dynamic，避免高速移动穿透；
• 确认Constraints中三个旋转轴均勾选冻结（代码已设置，但需检查组件面板）；
• 确保斜坡碰撞体未开启Is Trigger，否则会导致碰撞失效。

5. LayerMask赋值错误 #

检查Inspector面板中groundMask是否仅勾选Ground层，若误选其他层或未勾选Ground，会导致地面检测失效。

内容的提问来源于stack exchange，提问作者Big Glasses