双击打开SampleScene

创建一个Sprite——Square，命名为Ground，挂载Box Collider 2D，放在场景的下面，缩放至适合宽度

再创建一个Sprite，命名为Player，挂载Box Collider 2D和Rigidbody 2D，并且锁定Z旋转。

角色和地面

角色移动

新建Scripts文件夹，从中新建一个脚本，命名为Player

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using UnityEngine;

namespace ShootingEditor2D
{
    public class Player : MonoBehaviour
    {
        Rigidbody2D m_rigidbody;
        private void Awake()
        {
            m_rigidbody = GetComponent<Rigidbody2D>(); 
        }
        private void FixedUpdate()
        {
            var horizontalAxis = Input.GetAxis("Horizontal");

            m_rigidbody.velocity = new Vector2(horizontalAxis * 5, m_rigidbody.velocity.y);
        }
    }
}

挂载在Player上面

角色跳跃

首先我们在角色上创建空子对象，命名为“GroundCheck”；在上面挂载Circle Collider 2D组件，打开“is Trigger”并且把Radius设为0.1，将GroundCheck位置往下移到合适的位置

添加GroundCheck

教程中将Radius设为了0.01，这里为了截图方便暂用0.1半径，上图的is Trigger没有打开，别忘了打开

在Scripts文件夹中新建脚本，命名为Trigger2DCheck，挂载在GroundCheck上，并将TargetLayer设为“Default”

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using UnityEngine;

namespace ShootingEditor2D
{
    public class Trigger2DCheck : MonoBehaviour
    {
        public LayerMask TargetLayer;

        public int EnterCount;

        public bool Triggered
        {
            get
            {
                return EnterCount > 0;
            }
        }

        private void OnTriggerEnter2D(Collider2D collision)
        {
            if (IsInLayerMask(collision.gameObject, TargetLayer))
            {
                EnterCount++;
            }
        }

        private void OnTriggerExit2D(Collider2D collision)
        {
            if (IsInLayerMask(collision.gameObject, TargetLayer))
            {
                EnterCount--;
            }
        }

        bool IsInLayerMask(GameObject obj, LayerMask mask)
        {
            //obj的layer属性是一个int值，通过移位运算将它转化成运行时物理计算需要的LayerMask值
            //比如obj.layer = 7，则对应的layerMask值为：00000000000000000000000010000000
            var layerMaskofObj = 1 << obj.layer;
            //然后通过逻辑位运算来进行匹配，如果相同则为1，否则为0
            return (layerMaskofObj & mask) > 0;
        }
    }
}

这是一个比较通用的Tirgger脚本，并且包含了一些计数器的思路。

修改Palyer脚本

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using UnityEngine;

namespace ShootingEditor2D
{
    public class Player : MonoBehaviour
    {
        private bool m_JumpPressed;

        private Trigger2DCheck m_GroundCheck;//...

        Rigidbody2D m_Rigidbody2D;
        
        private void Awake()
        {
            m_Rigidbody2D = GetComponent<Rigidbody2D>(); 
            m_GroundCheck = transform.Find("GroundCheck").GetComponent<Trigger2DCheck>();//...
        }

        private void Update()
        {
            if(Input.GetButtonDown("Jump"))
                m_JumpPressed = true;
        }

        private void FixedUpdate()
        {
            var horizontalAxis = Input.GetAxis("Horizontal");

            m_Rigidbody2D.velocity = new Vector2(horizontalAxis * 5, m_Rigidbody2D.velocity.y);

            var isOnGround = m_GroundCheck.Triggered;//...

            if (m_JumpPressed && isOnGround)//...
            {
                m_Rigidbody2D.velocity = new Vector2(m_Rigidbody2D.velocity.x, 5);
            }

            m_JumpPressed = false;

        }
    }
}

这样就可以正常跳跃了