为什么会出现此错误：Assets\\Character2DController.cs(35,21): error CS0103: The name 'Physics2d' does not exist in the current context

Question

so for context I'm trying to make the controller of the character, and I'm learning c# so, if you guys have some more tips for te code, please tell code:

using UnityEngine;

public class Character2DController : MonoBehaviour
{
    public float MovementSpeed = 10;
    public float JumpForce;
    bool isGrounded;
    public Transform GroundCheck;
    public LayerMask groundLayer;

    private Rigidbody2D _rigidbody;

    private void Start()
    {
        _rigidbody = GetComponent<Rigidbody2D>();
       
    }

     void Update()
    {
        var movement = Input.GetAxis("Horizontal");
        transform.position  += new Vector3 (movement, 0 ,0) * Time.deltaTime * MovementSpeed;
 
        if (Input.GetKeyDown(KeyCode.Space))
        {
            if (isGrounded)
            {
            _rigidbody.velocity = Vector2.up * JumpForce;
            }
        }
    }
    private void FixedUpdate()
    {
       isGrounded = Physics2d.OverlapCircle(GroundCheck.position, 0.2f, groundLayer);

    }
}

Answer 1

Unity provides you lots of Physics function APIs for 2D and 3D.

To access the 2D functions use Physics2D static class, not Physics2d. To access the 3D functions use Physics3D static class, not Physics3d.