C# 脚本导致 Unity 编辑器崩溃

Question

我的统一脚本中有一个非常简单或非常复杂的问题。简单地说，当尝试在下面显示的方法中使用打开列表上的 .Add 或 .Insert 方法时，Unity 编辑器停止响应任何输入并挂起，直到在任务管理器中强制关闭。

有问题的方法：

    private void addToOpen(location l){ //causes editor crash
        int fScore = l.getF (); //f score of the location to add
        int count = open.Count; //number of values in the list
        int index = 0; //index to insert the location

        Debug.Log ("count " + count);
        while (index < count) {
            if(fScore >= open[index].getF()){
                break;
            }
            index++;
        }

        open.Insert(index, temp);
    }

代码正在尝试实现 A* 寻路算法。
我正在尝试将下面网页中的代码翻译成 C#。

http://www.raywenderlich.com/4970/how-to-implement-a-pathfinding-with-cocos2d-tutorial

我的脚本的较大部分在下面提供上下文：

    using UnityEngine;
    using System.Collections;
    using System.Collections.Generic; //for lists
    using System; //for broad use of "Exception"

    public class MouseBasedMovement : MonoBehaviour {

public GameObject map; //Holds the map object
private MapDataA mapdataa; //stores reference to data script
public Camera mainCamera;
void Awake(){
    mapdataa = map.GetComponent<MapDataA> (); //Links variable with component
}

//object for storing tile locations
public class location{
    public int xCoor;
    public int yCoor;
    //methods rarely interact with f as it is usually ignored, I tried to keep it isolated from extra interactions and assignments
    public int f;
    location parent; //location the object came from in A* algorithm
    public int g;
    public int h;

    public location(){
        xCoor = 0;
        yCoor = 0;
    }

    public location(int x, int y){
        xCoor = x;
        yCoor = y;
    }

    public location(location l){
        //constructor creates a copy of the location but does not copy the F value
        xCoor = l.getX ();
        yCoor = l.getY ();
    }

    public location(int x, int y, location a, location b){ //constructor for a*
        //x is x coordinate
        //y is y coordinate
        //a is starting position in algorithm ("from" tile)
        //b is target position in algorithm ("to" tile)

        xCoor = x;
        yCoor = y; 

        //g , h , f
        //g = getD(a, new location (x,y));
        //h = getD(new location(x,y), b);
        //f = getD(a, new location (x,y)) + getD(new location(x,y), b);
        //--- seems I can not nest constructors, going to simply do the same job by not using the getD method and using the method's logic + code instead.

        //private int getD(location a, location b){ //used for calculating g and h
            //if G,
            //a is the start point
            //b is the current square

            //if H, 
            //a is the current square
            //b is the endpoint

        //  int total = Math.Abs (a.getY () - b.getY ()) + Math.Abs (a.getX () - b.getX ());
        //  return total;
        //}

        g = Math.Abs (a.getY () - y) + Math.Abs (a.getX () - x);
        h = Math.Abs (y - b.getY ()) + Math.Abs (x - b.getX ());
        f = (Math.Abs (a.getY () - y) + Math.Abs (a.getX () - x)) + (Math.Abs (y - b.getY ()) + Math.Abs (x - b.getX ()));


    }

    public void setX(int x){
        xCoor = x;
    }

    public void setY(int y){
        yCoor = y;
    }

    public int getX(){
        return xCoor;
    }

    public int getY(){
        return yCoor;
    }

    public void setParent(location p){
        parent = p;
    }

    public location getParent(){
        return parent;
    }

    public void setF(int i){
        f = i;
    }

    public int getF(){
        return f;
    }

    public void setG(int gset){
        g = gset;
    }

    public int getG(){
        return g;
    }

    public void setH(int hset){
        h = hset;
    }

    public int getH(){
        return h;
    }

    public bool compareTo(location c){
        if ((c.getX () == this.getX ()) && (c.getY () == this.getY ())){
            return true;
        }else{
            return false;
        }
    }

    public string toString(){
        string str = "x: " + xCoor + " y: " + yCoor;
        return str;
    }
}

List<location> open = new List<location> (); //A* open list
List<location> closed = new List<location> (); //A* closed list
//method for the A* pathfinding algorithm's implementation in player movement
//Helped greatly in writing this section:
//http://www.raywenderlich.com/4946/introduction-to-a-pathfinding
//http://www.raywenderlich.com/4970/how-to-implement-a-pathfinding-with-cocos2d-tutorial
public void aStar(location a, location b){
    //a is starting position
    //b is ending position

    //checks to see if the destination is the same as the current position
    if (a.compareTo (b) == true) {
        Debug.Log ("Already There");
        return;
    }

    //Checks to see if the id of the destination tile is 1, and thus innacessable
    Debug.Log (mapdataa.mapData.GetLength (0));
    Debug.Log (mapdataa.mapData.GetLength (1));
    Debug.Log (b.getY ());
    Debug.Log (b.getX ());
    if (mapdataa.mapData[b.getY(), b.getX ()].getId () == 1){
        Debug.Log ("Destination tile is inaccessable");
        return;
    }

    //checks to see if the tile is highlighted (aka in range)
    GameObject[] inRange = GameObject.FindGameObjectsWithTag ("moveTransparent");
    bool found = false;
    foreach (GameObject trans in inRange) {
        if (trans.transform.position.x == b.getX () && trans.transform.position.y == b.getY ()){
            //tile is within range
            found = true;
        }
    }
    if (found == false) { //This section has worked in testing.
        //tile was never found to be within range
        Debug.Log ("Tile not in range/Tile not highlighted");
        return;
    }

    //begin A* actual algorithm implementation here
    bool pathFound = false;
    open.Add(new location ((int)transform.position.x, (int)transform.position.y, a, b)); //adds initial location of playable to open list 

    //testing
    Debug.Log ("open[0]: " + open[0].toString ());
    Debug.Log (open.Count);
    //end testing

    //above was previously an addToOpen method call, but I changed it to add, it SHOULD not affect logic, and may fix bugs
    location current = new location ();
    location temp = new location ();

    //Something in here (main algorithmic loop) is causing the crash
    do{
        //Get the lowest F score step
        //Because the list is ordered, the first step always has the lowest F score
        current = open[0];

        //add the current step to the closed list
        closed.Add (current);

        //remove the current step from the open list
        open.RemoveAt (0);

        //if current is the desired tile coordinate, the algorithm is complete
        if(current.compareTo (b)){
            pathFound = true;
            temp = current;
            Debug.Log ("Path Found");
            //LOOK INTO THIS! PARENT CHILD STRUCTURE NEEDS TO BE CONSIDERED
            do{
                Debug.Log (temp);
                temp = temp.getParent();
            }while(temp != null);
            break;
        }

        //get the adjacent tiles to the current step
        location[] adjSteps = getAdjacent (current,a,b);

        foreach (location loc in adjSteps){
            //check if the step isn't already in the closed set
            if (closed.Contains (loc)){
                continue; //effectively ignores it
            }

            //check if the step is already in the open list
            //NOTE: the line here in the source material is iffy, there might be functionality that I am not implementing
            if (open.Contains (loc) == false){
                //aka, not in the open list

                //set current step as the parent
                loc.setParent (current);                                                     //3

                //G score is parent g score + 1 (cost to move from parent to it)
                loc.setG (current.getG () + 1);                                              //4

                //compute H score
                loc.setH (getD (loc, b));                                                    //5

                //adding it to the open list
                addToOpen(loc);

            }else{
                //aka, already in the open list
                int index = open.IndexOf (loc); 
                //loc = open[index];

                //check to see if the G score is equal to the parent g score + cost to move(1)
                if(current.getG () + 1 < open[index].getG ()){
                    //The G score is equal to the parent G score + the cost to move to it
                    open[index].setG (current.getG () + 1);

                    //because the G score changed, f may change too
                    //so to keep the open list ordered, we have to remove and reinsert it

                    location locB = new location(open[index]); //added to circumvent bug

                    //remove from the list
                    open.RemoveAt (index);

                    //reinsert it
                    addToOpen (locB); //replaced loc with locB to circumvent bug
                }
            }

        }

    }while(open.Count > 0);

    if (!pathFound) { //no path found
        Debug.Log ("The algorithm failed to discover a path");
    }

}


    private void addToOpen(location l){ //causes editor crash
        int fScore = l.getF (); //f score of the location to add
        int count = open.Count; //number of values in the list
        int index = 0; //index to insert the location

        Debug.Log ("count " + count);
        while (index < count) {
            if(fScore >= open[index].getF()){
                break;
            }
            index++;
        }

        open.Insert(index, temp);
    }

//majorly reworked to prohibit returning null values to avoid editor crash while fixing bugs
private location[] getAdjacent(location l, location a, location b){
    location[] adjacents = new location[4];
    GameObject[] inRange = GameObject.FindGameObjectsWithTag ("moveTransparent");
    bool found = false;
    int counter = 0;

    //up 
    location up = new location (l.getX (), l.getY () + 1,a ,b);
    foreach (GameObject trans in inRange) {
        if (trans.transform.position.x == up.getX () && trans.transform.position.y == up.getY ()){
            //tile is within range
            found = true;
        }
    }
    if ((found == true) && (mapdataa.mapData [up.getY (), up.getX ()].getId () == 0)) { //if tile is within range and is acessable
        adjacents [counter] = up; //add it to the list
        counter++;
    }
    found = false; //reset found variable

    //down
    location down = new location (l.getX (), l.getY () -1,a,b);
    foreach (GameObject trans in inRange) {
        if (trans.transform.position.x == down.getX () && trans.transform.position.y == down.getY ()){
            //tile is within range
            found = true;
        }
    }
    if ((found == true) && (mapdataa.mapData [down.getY (), down.getX ()].getId () == 0)) { //if tile is within range and is acessable
        adjacents [counter] = down; //add it to the list
        counter++;
    }
    found = false; //reset found variable

    //left
    location left = new location (l.getX () -1, l.getY (),a,b);
    foreach (GameObject trans in inRange) {
        if (trans.transform.position.x == left.getX () && trans.transform.position.y == left.getY ()){
            //tile is within range
            found = true;
        }
    }
    if ((found == true) && (mapdataa.mapData [left.getY (), left.getX ()].getId () == 0)) { //if tile is within range and is acessable
        adjacents [counter] = left; //add it to the list
        counter++;
    }
    found = false; //reset found variable

    //right
    location right = new location (l.getX () +1, l.getY (),a,b);
    foreach (GameObject trans in inRange) {
        if (trans.transform.position.x == right.getX () && trans.transform.position.y == right.getY ()){
            //tile is within range
            found = true;
        }
    }
    if ((found == true) && (mapdataa.mapData [right.getY (), right.getX ()].getId () == 0)) { //if tile is within range and is acessable
        adjacents [counter] = right; //add it to the list
        counter++;
    }
    found = false; //reset found variable

    if (counter < 4) { //if statement is logically useless, but for the sake of trying to get to work, I'm leaving it as is.  Once it runs, try removing the if statement and test again.
        adjacents = retract (adjacents, 4-counter);
    }

    return adjacents;
}

private int getD(location a, location b){ //used for calculating g and h
    //implements the "Manhatten method" of determining total vertical and horizontal distance on a grid

    //if G,
    //a is the start point
    //b is the current square

    //if H, 
    //a is the current square
    //b is the endpoint

    int total = Math.Abs (a.getY () - b.getY ()) + Math.Abs (a.getX () - b.getX ());
    return total;
}

bool ran = false;
public void Update(){
    if (ran == false) {
        highlight ();
        ran = true;
    }
    if (Input.GetMouseButtonDown (0)) { //if left click
        Debug.Log ("Begin Update method A* implementation testing");
        aStar (new location((int)transform.position.x,(int)transform.position.y),new location((int)((((mainCamera.transform.position.x * 64) - (.5 * Screen.width)) + Input.mousePosition.x) / 64),(int)((((mainCamera.transform.position.y * 64) - (.5 * Screen.height)) + Input.mousePosition.y) / 64)));
        Debug.Log ("End Update method A* implementation testing");
    }
}

}

Answer 1

我无法真正调试它，因为我没有完整的上下文，但这是我查看源代码的猜测

//This line seems to cause the editor crash
open.Insert (index, l);

我们来看看这里用到的变量：

• open: 存储元素的列表（计数可能为零）
• index：一个索引，从 1 开始（并且保持在一个 if open.Count==0）

也许您已经发现了问题：列表有 0 个元素，而您正试图在位置 1 插入一个元素。C#（或 CLR，更确切地说）不太喜欢这个，只是抛出一个异常（在至少在 Visual Studio 中）。

崩溃的部分很有趣。由于您使用的是 Unity，我假设您使用 MonoDevelop 作为您的编辑器。每次异常时编辑器都会崩溃吗？ （尝试int a=1/0 或类似的测试）。如果没有，很可能您在 MonoDevelop 中发现了一个错误（在这种情况下，您应该提交错误报告）。当然也可能是其他原因导致崩溃（例如算法中的无限循环）。

Answer 2

首先，open.InsertRange(index, temp) 是错误的。改回open.Insert(index, l)。

其次，当您添加相邻的图块时，您不会更新 F 分数。如果它是一个新图块，你设置 G 和 H 但不是 F。如果它已经在打开列表中，你甚至可以评论“因为 G 分数改变了，f 也可能改变”但你不更新 F。而且 F 将永远改变，因为 F = G + H。

也许退后一步，想想算法应该如何工作。在您的教程中使用introduction 或来自Wikipedia 的文章以及一些伪代码。

如果它仍然卡在某个地方，添加一些 Debug.Log() 到你的 aStar 循环中，这样你就可以跟踪你的算法在做什么。建议测试一个小世界，否则你会迷路;)