unity 2D，角色不会移动

Question

So i have followed this guide https://learn.unity.com/tutorial/live-session-2d-platformer-character-controller#5c7f8528edbc2a002053b695

And i've basically followed everything step by step.

Here is the code.

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

public class PhysicsObject : MonoBehaviour
{
    public float minGroundNormalY = .65f;
    public float gravityModifier = 1f;
    protected Vector2 targetVelocity;
    protected bool grounded;
    protected Vector2 groundNormal;

    protected Rigidbody2D rb2d;
    protected Vector2 velocity;
    protected ContactFilter2D contactFilter;
    protected RaycastHit2D[] hitBuffer = new RaycastHit2D[16];
    protected List<RaycastHit2D> hitBufferList = new List<RaycastHit2D>(16);

    protected const float minMoveDistance = 0.001f;
    protected const float shellRadius = 0.01f;

    void OnEnable()
    {
        rb2d = GetComponent<Rigidbody2D>();
    }

    // Start is called before the first frame update
    void Start()
    {
        contactFilter.useTriggers = false;
        contactFilter.SetLayerMask(Physics2D.GetLayerCollisionMask (gameObject.layer));
        contactFilter.useLayerMask = true;
    }

    // Update is called once per frame
    void Update()
    {
        targetVelocity = Vector2.zero;
        ComputeVelocity();
    }

    protected virtual void ComputeVelocity()
    {
    }

    void FixedUpdate()
    {
        velocity += gravityModifier * Physics2D.gravity * Time.deltaTime;
        velocity.x = targetVelocity.x;

        grounded = false;

        Vector2 deltaPosition = velocity * Time.deltaTime;
        Vector2 moveAlongGround = new Vector2(groundNormal.y, -groundNormal.x);
        Vector2 move = moveAlongGround * deltaPosition.x;
        Movement(move, false);

        move = Vector2.up * deltaPosition.y;
        Movement(move, true);
    }

    void Movement(Vector2 move, bool yMovement)
    {
        float distance = move.magnitude;
        if (distance > minMoveDistance)
        {
           int count =  rb2d.Cast(move, contactFilter, hitBuffer, distance + shellRadius);
            hitBufferList.Clear();
            for (int i = 0; i < count; i++)
            {
                hitBufferList.Add(hitBuffer[i]);
            }

            for (int i = 0; i < hitBufferList.Count; i++)
            {
                Vector2 currentNormal = hitBufferList[i].normal;
                if (currentNormal.y < minGroundNormalY)
                {
                    grounded = true;
                    if (yMovement)
                    {
                        groundNormal = currentNormal;
                        currentNormal.x = 0;
                    }
                }
                float projection = Vector2.Dot(velocity, currentNormal);

                if (projection < 0)
                {
                    velocity = velocity - projection * currentNormal;
                }
                float modifiedDistance = hitBufferList[i].distance - shellRadius;
                distance = modifiedDistance < distance ? modifiedDistance : distance;
            }
        }
        rb2d.position = rb2d.position + move.normalized * distance;
    }
}

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

public class PlayerPlatformerController : PhysicsObject
{
    public float jumpTakeOffSpeed = 7;
    public float maxSpeed = 7;

    // Start is called before the first frame update
    void Start()
    {
    }

    protected override void ComputeVelocity()
    {
        Vector2 move = Vector2.zero;
        move.x = Input.GetAxis("Horizontal");

        if (Input.GetButtonDown("Jump") && grounded)
        {
            velocity.y = jumpTakeOffSpeed;
        }
        else if (Input.GetButtonUp("Jump"))
        {
            if (velocity.y > 0)
            {
                velocity.y = velocity.y * 0.5f;
            }
        }
        targetVelocity = move * maxSpeed;
    }
}

If you check that link it will probably have some animations added to it, i have not gotten that far yet.

So atm my char just stands completly still and does not move. Below is the picture.

Answer 1

When inheriting from Unity objects (MonoBehaviours in general), if you create a new Unity lifecycle function (Start, Awake, Update, etc), it will ignore the inheriting class' implementation.

In this case, PlayerPlatformerController is implementing an empty Start , which means Start won't be called on PhysicsObject .

This means this code will not run :

contactFilter.useTriggers = false;
contactFilter.SetLayerMask(Physics2D.GetLayerCollisionMask (gameObject.layer));
contactFilter.useLayerMask = true;

Which could be a game breaking issue since you are modifying physics related arguments there.