当我不给它任何输入时，我将如何增加汽车的摩擦力使其不会滑行？

Question

每个人。我是 Unity 2D 和 C# 的新手，我想知道如何阻止我的车在我的游戏中滑行和向前滑动，因为如果我不希望它这样做，因为如果它滑得太厉害了。我希望这样，如果我不给汽车任何输入，或者给汽车几乎立即停止或开始向另一方向移动的计数器输入。我尝试过创建 Physics2D 材质并增加摩擦力，但它确实对游戏玩法没有影响。我也尝试过检查，如果没有玩家输入，则 rb.velocity 设置为 0，或当前值的 0.2 左右，因此它是一个更平滑的停止，但只有在玩家移动然后放开移动键，如果他们尝试向相反的方向移动，则不会。我还考虑过通过将先前位置与当前位置进行比较来检查汽车的移动方向，然后向相反方向增加力以停止汽车，但这似乎非常耗费性能，我真的不知道我会去哪里开始。如果有人对我将如何做这件事有任何建议，请告诉我如何做。这是我到目前为止的代码：

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

public class CarController : MonoBehaviour
{

public Rigidbody2D carRigidbody;
public Rigidbody2D backTire;
public Rigidbody2D frontTire;

private float movement;
public float fspeed = 100;
public float bspeed = 60;
public float carTorque = 10;
public float decVel = .9f;
private bool beganMoving;



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

}

// Update is called once per frame
void Update()
{
    movement = Input.GetAxis("Horizontal");
}

void FixedUpdate() {
    if (movement == 1 || movement == -1) {
        beganMoving = true;
    }
    if (movement == 0 && beganMoving) {
        backTire.velocity = new Vector2 (backTire.velocity.x * decVel * Time.fixedDeltaTime, backTire.velocity.y); 
        frontTire.velocity = new Vector2 (backTire.velocity.x * decVel * Time.fixedDeltaTime, backTire.velocity.y);
        
    }
    
    
    backTire.AddTorque(-movement * bspeed * Time.fixedDeltaTime);
    frontTire.AddTorque(-movement * fspeed * Time.fixedDeltaTime);
    carRigidbody.AddTorque(-movement * carTorque * Time.fixedDeltaTime);
}

}

Answer 1

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

public class CarController : MonoBehaviour
{

public Rigidbody2D carRigidbody;
public Rigidbody2D backTire;
public Rigidbody2D frontTire;

private float movement;
public float fspeed = 100;
public float bspeed = 60;
public float carTorque = 10;
public float decVel = .9f;
private bool beganMoving;


// Update is called once per frame
void Update()
{
    movement = Input.GetAxis("Horizontal");
}

void FixedUpdate() {
    if (movement == 1 || movement == -1) {
        beganMoving = true;
    }
    if (movement <= 0.1f)
    {
        beganMoving = false;
    }
    if (movement <= 0.8f && beganMoving) // If the movement is starting to decrease and it the car has already started moving, set the velocities to zero.
    {
        backTire.velocity = Vector3.zero;
        frontTire.velocity = Vector3.zero;
    }
    if (movement == 0 && beganMoving) {
        backTire.velocity = new Vector2 (backTire.velocity.x * decVel * Time.fixedDeltaTime, backTire.velocity.y); 
        frontTire.velocity = new Vector2 (backTire.velocity.x * decVel * Time.fixedDeltaTime, backTire.velocity.y);
        
    }
    
    
    backTire.AddTorque(-movement * bspeed * Time.fixedDeltaTime);
    frontTire.AddTorque(-movement * fspeed * Time.fixedDeltaTime);
    carRigidbody.AddTorque(-movement * carTorque * Time.fixedDeltaTime);
}

Answer 2

大家好，浏览过这个问题的人都有类似的问题。我最终解决这个问题的方法是在这里实现整个代码块：

isGrounded = Physics2D.OverlapCircle(groundCheck.position, checkRadius, whatIsGround);

    if (movement == 1 || movement == -1) {
        beganMoving = true;
    } // this makes sure we've started moving which will be used later
    if (movement == 0 && isGrounded) {
        backTire.velocity = new Vector2 (backTire.velocity.x * .8f * Time.fixedDeltaTime, backTire.velocity.y); 
        frontTire.velocity = new Vector2 (frontTire.velocity.x * .8f * Time.fixedDeltaTime, frontTire.velocity.y);  // this whole if statement is so that our car will stop or decelerate when no input is given to it as to stop  it from rolling all across the ground
    }
    if (movement > 0 && prevMove < 0) { // checks if we are moving forward (right) when we used to move backwards (left)
        backTire.velocity = new Vector2 (backTire.velocity.x * decVel * Time.fixedDeltaTime, backTire.velocity.y); 
        frontTire.velocity = new Vector2 (frontTire.velocity.x * decVel * Time.fixedDeltaTime, frontTire.velocity.y); //stops us if the if statement returns true
        prevMove = 1; // sets our previous movement to moving forward to make it not repeat itself and to check with later on
    } else if (movement < 0 && prevMove > 0 ) { // checks if we are moving backwards when we used to be moving forwards
        backTire.velocity = new Vector2 (backTire.velocity.x * decVel * Time.fixedDeltaTime, backTire.velocity.y); 
        frontTire.velocity = new Vector2 (frontTire.velocity.x * decVel * Time.fixedDeltaTime, frontTire.velocity.y); //stops car
        prevMove = -1; // sets previous movement to moving backwards
    } else {
        if (beganMoving == true) { // when we start moving we set the previous movement to which ever direction we decided to first move in
        prevMove = movement;
        beganMoving = false; // set began moving to false. This doesn't make sense logically since we did begin moving but it's so this if statement doesn't repeat itself again
        }
    }

我已将 cmets 包括在内，因此您有望了解我做了什么以及为什么这样做。我希望这可以帮助任何有类似问题的人。