Unity 2Dアクションの作り方【敵・当たり判定編】

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

 public class Player : MonoBehaviour
 {
     #region//インスペクターで設定する
     [Header("移動速度")] public float speed;
     [Header("重力")] public float gravity;
     [Header("ジャンプ速度")] public float jumpSpeed;
     [Header("ジャンプする高さ")] public float jumpHeight;
     [Header("ジャンプする長さ")] public float jumpLimitTime;
     [Header("接地判定")] public GroundCheck ground;
     [Header("天井判定")] public GroundCheck head;
     [Header("ダッシュの速さ表現")] public AnimationCurve dashCurve;
     [Header("ジャンプの速さ表現")] public AnimationCurve jumpCurve;
     #endregion

     #region//プライベート変数 
     private Animator anim = null; 
     private Rigidbody2D rb = null; 
     private bool isGround = false; 
     private bool isJump = false; 
     private bool isRun = false; 
     private bool isHead = false; 
     private bool isDown = false; 
     private float jumpPos = 0.0f; 
     private float dashTime = 0.0f;
     private float jumpTime = 0.0f;
     private float beforeKey = 0.0f;
     private string enemyTag = "Enemy";
     #endregion 

     void Start() 
     {
          //コンポーネントのインスタンスを捕まえる
          anim = GetComponent<Animator>();
          rb = GetComponent<Rigidbody2D>();
     } 

     void FixedUpdate()
     {
         if (!isDown)
         {
              //接地判定を得る
              isGround = ground.IsGround();
              isHead = head.IsGround(); 
         
              //各種座標軸の速度を求める
              float xSpeed = GetXSpeed();
              float ySpeed = GetYSpeed();

              //アニメーションを適用
              SetAnimation();

              //移動速度を設定
              rb.velocity = new Vector2(xSpeed, ySpeed);
         }
         else
         {
              rb.velocity = new Vector2(0, -gravity);
         }
     }

     /// <summary>
     /// Y成分で必要な計算をし、速度を返す。
     /// </summary> 
     /// <returns>Y軸の速さ</returns> 
     private float GetYSpeed() 
     {
          float verticalKey = Input.GetAxis("Vertical");
          float ySpeed = -gravity;

          if (isGround)
          {
              if (verticalKey > 0)
              {
                  ySpeed = jumpSpeed;
                  jumpPos = transform.position.y; //ジャンプした位置を記録する
                  isJump = true;
                  jumpTime = 0.0f;
              }
              else
              {
                  isJump = false;
              }
          }
          else if (isJump)
          {
             //上方向キーを押しているか
　　　　　　　bool pushUpKey = verticalKey > 0;
　　　　　　　//現在の高さが飛べる高さより下か
　　　　　　　bool canHeight = jumpPos + jumpHeight > transform.position.y;
　　　　　　　//ジャンプ時間が長くなりすぎてないか
　　　　　　　bool canTime = jumpLimitTime > jumpTime;

　　　　　　　if (pushUpKey && canHeight && canTime && !isHead)
              {
                  ySpeed = jumpSpeed;
                  jumpTime += Time.deltaTime;
              }
              else
              {
                  isJump = false;
                  jumpTime = 0.0f;
              }
          }

          if (isJump)
          {
              ySpeed *= jumpCurve.Evaluate(jumpTime);
          }
          return ySpeed;
     } 

     /// <summary> 
     /// X成分で必要な計算をし、速度を返す。 
     /// </summary> 
     /// <returns>X軸の速さ</returns> 
     private float GetXSpeed() 
     {
          float horizontalKey = Input.GetAxis("Horizontal");
          float xSpeed = 0.0f;
          if (horizontalKey > 0)
          {
              transform.localScale = new Vector3(1, 1, 1);
              isRun = true;
              dashTime += Time.deltaTime;
              xSpeed = speed;
          }
          else if (horizontalKey < 0)
          {
              transform.localScale = new Vector3(-1, 1, 1);
              isRun = true;
              dashTime += Time.deltaTime;
              xSpeed = -speed;
          }
          else
          {
              isRun = false;
              xSpeed = 0.0f;
              dashTime = 0.0f;
          }

          //前回の入力からダッシュの反転を判断して速度を変える
          if (horizontalKey > 0 && beforeKey < 0)
          {
              dashTime = 0.0f;
          }
          else if (horizontalKey < 0 && beforeKey > 0)
          {
              dashTime = 0.0f;
          }
          beforeKey = horizontalKey;

          xSpeed *= dashCurve.Evaluate(dashTime);
          beforeKey = horizontalKey;
          return xSpeed; 
     } 

     /// <summary> 
     /// アニメーションを設定する 
     /// </summary> 
     private void SetAnimation() 
     {
          anim.SetBool("jump", isJump);
          anim.SetBool("ground", isGround);
          anim.SetBool("run", isRun); 
     }

     #region//接触判定      
     private void OnCollisionEnter2D(Collision2D collision) 
     {
          if (collision.collider.tag == enemyTag)
          {
               anim.Play("player_down");
               isDown = true;
          }
     }
     #endregion
 }