如何在 Unity2D 中检查我的 2D 角色是否在空中？

Question

所以我试图让我的 2D 角色跳跃。 如果我在地面上跑步，它可以完美运行，但是当我撞到墙壁时，它就会出现问题：我什至可以在空中跳跃。 我试过用 bool 变量解决这个问题，但没有奏效。 我想过检查玩家是否在空中，然后将 is_on_ground 变量设置为 false。 显然，玩家只有在地面上时才应该跳跃。 我的代码如下：

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

public class PlayerMovement : MonoBehaviour
{
    private bool canJump = false;
    public SpriteRenderer sr;
    private bool facingRight;
    private Animator animator;
    private bool is_on_ground;
    public Button leftBtn;
    public Button rightBtn;
    public Button jumpBtn;
    public float max_velocity;
    public float velocity;
    public float jump_scalar;
    private Rigidbody2D rb;
    private float x_movement;
    private Vector2 movement;
    void Start() {
        canJump = true;
        facingRight = true;
        animator = gameObject.GetComponent<Animator>();
        leftBtn.onClick.AddListener(moveLeft);
        rightBtn.onClick.AddListener(moveRight);
        jumpBtn.onClick.AddListener(jump);
        rb = gameObject.GetComponent<Rigidbody2D>();
    }
    private void FixedUpdate() {
        if (rb.velocity.magnitude < max_velocity) {
            movement = new Vector2(x_movement, 0);
            rb.AddForce(movement * velocity);
        }
    }
    private void OnCollisionEnter2D(Collision2D collision) {
        if (CollisionIsWithGround(collision)) {
            animator.SetBool("isJumping", false);
            canJump = true;
        }
        if (collision.collider.tag == "wall") {
            canJump = false;
        }
        is_on_ground = true;

    }
    private void OnCollisionExit2D(Collision2D collision) {
        if (!CollisionIsWithGround(collision)) {
            is_on_ground = false;
        }
        if (collision.collider.tag == "wall") {
            is_on_ground = true;
            canJump = true;
        }
    }
    private bool CollisionIsWithGround(Collision2D collision) {
        bool is_with_ground = false;
        foreach (ContactPoint2D c in collision.contacts) {
            Vector2 collision_direction_vector = c.point - rb.position;
            if(collision_direction_vector.y < 0) {
                is_with_ground = true;
            }
        }
        return is_with_ground;
    }
    public void moveLeft() {
        if (is_on_ground) {
            animator.SetBool("isJumping", false);
        }
        animator.SetBool("isRunning", true);
        sr.flipX = true;
        facingRight = false;
        x_movement = -1;
    }
    public void onRelease() {
        animator.SetBool("isRunning", false);
        x_movement = 0;
        if(is_on_ground) {
            animator.SetBool("isJumping", false);
            rb.velocity = Vector3.zero;
        }
    }
    public void moveRight() {
        if (is_on_ground) {
            animator.SetBool("isJumping", false);
        }
        if (!facingRight) {
            sr.flipX = false;
            facingRight = true;
            animator.SetBool("isRunning", true);
        } else {
            animator.SetBool("isRunning", true);
        }
        x_movement = 1;
    }
    public void jump() {
        if(is_on_ground) {
            if (canJump) {
                animator.SetBool("isJumping", true);
                Vector2 jumpForce = new Vector2(0, jump_scalar * 100);
                rb.AddForce(jumpForce);
            }
        }
    }
}

the problem looks like this

Answer 1

除了直接向下进行光线投射，您还可以在玩家的脚周围投射一个圆圈。

您需要添加一个空的地面检查游戏对象作为玩家的子对象，并将其变换放置在玩家的脚下。接下来，您需要在检查器中为m_WhatIsGround LayerMask 定义哪些层算作地面。

然后在FixedUpdate() 中检查地面检查变换是否在到地面的某个半径范围内。

// A mask determining what is ground to the character
[SerializeField] private LayerMask m_WhatIsGround;

// A position marking where to check if the player is grounded.
[SerializeField] private Transform m_GroundCheck;

// Radius of the overlap circle to determine if grounded
const float k_GroundedRadius = 0.3f;

private void FixedUpdate() {
    is_on_ground = false;

    // The player is grounded if a circlecast to the groundcheck position hits anything designated as ground
    // This can be done using layers instead but Sample Assets will not overwrite your project settings.
    Collider2D[] colliders = Physics2D.OverlapCircleAll(m_GroundCheck.position, k_GroundedRadius, m_WhatIsGround);
    for (int i = 0; i < colliders.Length; i++) {
        if (colliders[i].gameObject != gameObject) {
            is_on_ground = true;
        }
    }
}

这个方法的教程可以在Brackey's video找到。

Answer 2

您可以在每个FixedUpdate 中对地板执行Physics2d.Raycast。当到最近对象的范围小于 0.01 或类似的值时，您将测试它是否是地板，如果是，则设置 is_on_ground = true，如果不是，则执行 is_on_ground = false

示例：

float raycastDistance = 0.05f;
RaycastHit2D hit = Physics2D.Raycast(transform.position, -Vector2.up, raycastDistance);
if (hit.collider != null && hit.transform.gameObject.layer == LayerMask.NameToLayer("ground"))
    is_on_ground = true;
} else {
    is_on_ground = false;
}

这应该可行。您显然必须在本例中定义一个名为 ground 的层并将其添加到每个 ground。