【发布时间】：2015-12-15 14:36:19
【问题描述】：
我正在尝试在我的 Unity 项目中以程序方式在随机位置生成恒定数量的建筑物。但是，我得到一个无限循环。
这是我的代码（C#）：
using UnityEngine;
using System.Collections;
using System.Collections.Generic;
public class GenerateMap : MonoBehaviour {
public GameObject plane;
public LayerMask unwalkableMask;
Node[,] Map;
public Vector2 gridWorldSize;
GameObject thisBuilding;
public float nodeRadius;
float nodeDiameter;
int gridSizeX, gridSizeY;
int scale;
public int numBuildings = 5;
public int numPrefabs;
public List<Vector3> positions = new List<Vector3> ();
public List<GameObject> buildingPrefabs = new List<GameObject>();
void Awake(){
plane = GameObject.CreatePrimitive(PrimitiveType.Plane);
scale = 15; // scaling the plane gives an 5*scale x 5*scale (x-axis x z-axis) plane, set to 50
plane.transform.localScale = new Vector3 (scale, 1, scale); //scales only in x and z dimensions
}
// Use this for initialization
void Start () {
//GameObject building1 = Resources.Load("Buildings/building1") as GameObject;
//GameObject building2 = (GameObject)Resources.Load ("Buildings/building2");
//GameObject building3 = (GameObject)Resources.Load ("Buildings/building3");
nodeDiameter = nodeRadius*2;
gridSizeX = Mathf.RoundToInt(gridWorldSize.x/nodeDiameter);
gridSizeY = Mathf.RoundToInt(gridWorldSize.y/nodeDiameter);
Generate();
}
//int i = 0;
void Generate(){
for(int i =0; i<numBuildings; i++){
//while(i < numBuildings){
CreateGrid();
List<Node> unwalkables = getUnwalkables();
thisBuilding =(GameObject)InstantiatePrefab(); i++;
CreateGrid();
List<Node> unwalkables2 = getUnwalkables(thisBuilding);
foreach(Node n in unwalkables){
//Debug.Log(n.worldPosition);
bool breaking = false;
foreach(Node m in unwalkables2){
if(n.worldPosition==m.worldPosition){
Destroy(thisBuilding);
i=i-1;
Debug.Log("i after fail " + i);
breaking = true;
break;
}
if(breaking)
break;
}
}
}
}
Object InstantiatePrefab() {
int number = Random.Range (0, numPrefabs);
Vector3 position = new Vector3 (Random.Range (-scale*5, scale*5), 0, Random.Range (-scale*5, scale*5)); //random position in the x,z-plane
positions.Add (position);
position.y = buildingPrefabs [number].transform.position.y; //make sure they spawn on top of the plane instead of y=0 w.r.t. their pivot point
Object building;
if (number != 2) {
building = Instantiate (buildingPrefabs [number], position, Quaternion.Euler (-90f, 0f, 0f));
} else {
building = Instantiate (buildingPrefabs [number], position, Quaternion.identity);
}
return building;
}
void CreateGrid(){
Map = new Node[gridSizeX, gridSizeY];
Vector3 worldBottomLeft = transform.position - Vector3.right * gridWorldSize.x/2 - Vector3.forward * gridWorldSize.y/2;
for(int x=0; x<gridSizeX; x++){
for(int y=0; y<gridSizeX; y++){
Vector3 worldPoint = worldBottomLeft + Vector3.right * (x*nodeDiameter + nodeRadius) + Vector3.forward * (y*nodeDiameter+ nodeRadius);
bool walkable = !(Physics.CheckSphere(worldPoint, nodeRadius, unwalkableMask));
Map[x,y] = new Node(walkable, worldPoint, x, y);
}
}
}
void OnDrawGizmos()
{
Gizmos.DrawWireCube(transform.position, new Vector3(gridWorldSize.x, 1, gridWorldSize.y));
if (Map != null)
{
foreach (Node n in Map)
{
Gizmos.color = (n.walkable)?Color.white:Color.red;
Gizmos.DrawCube(n.worldPosition, new Vector3(nodeDiameter-.1f, nodeDiameter*0.5f, nodeDiameter-.1f));
//Vector3.one * (nodeDiameter-.1f));
}
}
}
List<Node> getUnwalkables(){
List<Node> unwalk = new List<Node>();
foreach(Node n in Map){
if(!n.walkable)
unwalk.Add(n);
}
return unwalk;
}
List<Node> getUnwalkables(GameObject obj){
List<Node> unwalk = new List<Node>();
int borderWidth = 8; //x-dir
int borderHeight = 7; //z-dir
float RightBorder = obj.transform.position.x+nodeRadius+borderWidth*nodeDiameter;
float LeftBorder = obj.transform.position.x-nodeRadius-borderWidth*nodeDiameter;
float TopBorder = obj.transform.position.z+nodeRadius+borderHeight*nodeDiameter;
float DownBorder = obj.transform.position.z-nodeRadius-borderHeight*nodeDiameter;
//Vector3 worldBottomLeft = transform.position - Vector3.right * gridWorldSize.x/2 - Vector3.forward * gridWorldSize.y/2;
foreach(Node n in Map){
if(n.worldPosition.x<RightBorder && n.worldPosition.x>LeftBorder
&& n.worldPosition.z>DownBorder && n.worldPosition.z<TopBorder)
unwalk.Add(n);
}
return unwalk;
}
}
这个方法好像有问题：
void Generate(){
for(int i =0; i<numBuildings; i++){
//while(i < numBuildings){
CreateGrid();
List<Node> unwalkables = getUnwalkables();
thisBuilding =(GameObject)InstantiatePrefab(); i++;
CreateGrid();
List<Node> unwalkables2 = getUnwalkables(thisBuilding);
foreach(Node n in unwalkables){
//Debug.Log(n.worldPosition);
bool breaking = false;
foreach(Node m in unwalkables2){
if(n.worldPosition==m.worldPosition){
Destroy(thisBuilding);
i=i-1;
Debug.Log("i after fail " + i);
breaking = true;
break;
}
if(breaking)
break;
}
}
}
}
如果我删除该行：i=i-1;我没有无限循环，但我最终会得到比预期更少的建筑物。此行导致 for 循环再重复一次迭代，因此它将始终生成至少 'numBuildings' 数量的建筑物。
我在“foreach”循环中添加了中断语句，这样如果条件似乎多次满足，“i”就不会继续减少。但这似乎不起作用，一旦 numBuildings 大约为 5 或更多，它就会创建一个无限循环。发生这种情况时，我只能通过强制结束任务才能退出。
有谁知道我做错了什么，或者是否有更好的解决方案来始终生成大量建筑物？
如有必要，我已准备好回答有关代码/场景的任何问题。
【问题讨论】：
-
这可能是个人喜好，但您的代码格式使其难以阅读。
-
一般是别人要求完整的代码输出，所以提前贴出来。但要指出正确的方向：第二个代码块包含问题。你可以问任何看起来不清楚的问题。
-
您是否确定总是可能（在您的规则限制内）将
numBuildings建筑物选址？ -
抛开这个问题不谈，一般来说，在循环体中胡乱摆弄循环变量会使成功推理代码的行为变得更加困难。重新设计以避免这种情况。
标签： c# unity3d foreach infinite-loop procedural-generation