Unity 2D项目3个编译错误修复求助（附C#代码）

错误根源分析 #

你的代码里包含了HTML转义字符（比如=>、<、&&），这些字符会被C#编译器识别为无效语法，直接导致编译失败。另外需确认你的Unity项目使用的C#版本支持表达式体成员（=>语法），Unity 2018及以上版本默认支持，若版本过低需在项目设置中调整脚本运行时版本。

修复后的完整代码 #

PlayerMovement 类

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

public class PlayerMovement : MonoBehaviour
{
    private Camera camera;
    private new Rigidbody2D rigidbody;

    private Vector2 velocity;
    private float inputAxis;

    public float moveSpeed = 8f;
    public float maxJumpHeight = 5f;
    public float maxJumpTime = 1f;

    public float jumpForce => (2f * maxJumpHeight) / (maxJumpTime / 2f);
    public float gravity => (-2f * maxJumpHeight) / Mathf.Pow((maxJumpTime / 2f), 2);

    public bool grounded { get; private set; }
    public bool jumping { get; private set; }

    private void Awake()
    {
        rigidbody = GetComponent<Rigidbody2D>();
        camera = Camera.main;
    }

    private void Update()
    {
        HorizontalMovement();
        grounded = rigidbody.Raycast(Vector2.down);

        if (grounded)
        {
            GroundedMovement();
        }

        ApplyGravity();
    }

    private void HorizontalMovement()
    {
        inputAxis = Input.GetAxis("Horizontal");
        velocity.x = Mathf.MoveTowards(velocity.x, inputAxis * moveSpeed, moveSpeed * Time.deltaTime);
    }

    private void GroundedMovement()
    {
        velocity.y = Mathf.Max(velocity.y, 0f);
        jumping = velocity.y > 0f;

        if (Input.GetButtonDown("Jump"))
        {
            velocity.y = jumpForce;
            jumping = true;
        }
    }

    private void ApplyGravity()
    {
        bool falling = velocity.y < 0f;
        float multiplier = falling ? 2f : 1f;

        velocity.y += gravity * multiplier * Time.deltaTime;
        velocity.y = Mathf.Max(velocity.y, gravity / 2f);
    }

    private void FixedUpdate()
    {
        Vector2 position = rigidbody.position;
        position += velocity * Time.fixedDeltaTime;

        Vector2 leftEdge = camera.ScreenToWorldPoint(Vector2.zero);
        Vector2 rightEdge = camera.ScreenToWorldPoint(new Vector2(Screen.width, Screen.height));
        position.x = Mathf.Clamp(position.x, leftEdge.x + 0.5f, rightEdge.x - 0.5f);
        rigidbody.MovePosition(position);
    }
}

Extensions 类

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

public static class Extensions
{
    private static LayerMask layerMask = LayerMask.GetMask("Default");
    public static bool Raycast(this Rigidbody2D rigidbody, Vector2 direction)
    {
        if (rigidbody.isKinematic)
        {
            return false;
        }
        float radius = 0.25f;
        float distance = 0.375f;

        RaycastHit2D hit = Physics2D.CircleCast(rigidbody.position, radius, direction, distance, layerMask);
        return hit.collider != null && hit.rigidbody != rigidbody;
    }
}

额外运行注意事项 #

1. 确保Player对象上挂载了Rigidbody2D组件，且Gravity Scale设为0（代码中已手动处理重力逻辑）。
2. 场景中必须存在标记为MainCamera的相机，否则Camera.main会返回null导致报错。
3. 地面对象的Layer需设置为Default，否则扩展方法中的射线检测无法识别地面。

内容的提问来源于stack exchange，提问作者Alan Lienhard