（C#）A*演算法虛擬碼及原始碼
阿新 • • 發佈：2019-01-27
using UnityEngine; using System.Collections; public class Node { /*邏輯中用的*/ public int gCost; public int hCost; public int fCost { get { return gCost + hCost; } } public Node parent; /*在Unity當中用的*/ public bool canWalk; //網格的下標 public int gridX; public int gridY; //節點的位置 public Vector3 worldPos; public Node(bool _canWalk, Vector3 position, int x, int y) { canWalk = _canWalk; worldPos = position; gridX = x; gridY = y; } }
using UnityEngine; using System.Collections; using System.Collections.Generic; public class Grid : MonoBehaviour { //存放點節點的陣列 public Node[,] grid; //網格的大小 public Vector2 gridSize; //節點的大小 public float nodeRadius; public float nodeDiameter; //一個層，代表可不可以通過 public LayerMask cantLayer; //x和y方向上各有多少個格子 public int gridContX; public int gridContY; //起點 public Transform start; //用來儲存路徑的列表 public List<Node> path = new List<Node>(); void Start () { cantLayer = LayerMask.GetMask("CantWalk"); nodeDiameter = nodeRadius * 2; //gridContX = (int)(gridSize.x / nodeDiameter); gridContX = Mathf.RoundToInt(gridSize.x / nodeDiameter); gridContY = Mathf.RoundToInt(gridSize.y / nodeDiameter); grid = new Node[gridContX, gridContY]; CreatGrid(); } void Update () { } //建立格子 void CreatGrid() { //網格起點 Vector3 startPoint = transform.position - gridSize.y / 2 * Vector3.forward - gridSize.x / 2 * Vector3.right; for (int i = 0; i < gridContX; i++) { for (int j = 0; j < gridContY; j++) { Vector3 worldPos = startPoint + Vector3.right * (nodeDiameter * i + nodeRadius) + Vector3.forward * (nodeDiameter * j + nodeRadius); //檢測有沒有碰到不能走的層上的物體 bool canwalk = !Physics.CheckSphere(worldPos, nodeRadius, cantLayer); grid[i, j] = new Node(canwalk, worldPos, i, j); } } } //Unity中的輔助類 void OnDrawGizmos() { if (grid == null) { return; } foreach (Node node in grid) { if (node.canWalk) { Gizmos.color = Color.yellow; Gizmos.DrawCube(node.worldPos, (nodeDiameter - 0.02f) * new Vector3(1, 0.2f, 1)); } else { Gizmos.color = Color.red; Gizmos.DrawCube(node.worldPos, (nodeDiameter - 0.02f) * new Vector3(1, 0.2f, 1)); } } //畫出起點的位置 Node startNode = FindWithPosition(start.position); if (startNode.canWalk) { Gizmos.color = Color.black; Gizmos.DrawCube(startNode.worldPos, (nodeDiameter - 0.02f) * new Vector3(1, 0.2f, 1)); } //畫路徑 if(path != null) { foreach (var node in path) { Gizmos.color = Color.blue; Gizmos.DrawCube(node.worldPos, (nodeDiameter - 0.02f) * new Vector3(1, 0.2f, 1)); } } } //通過位置得到在哪一個格子 public Node FindWithPosition(Vector3 position) { //在x方向的佔比 float percentX = (position.x + gridSize.x / 2) / gridSize.x; float percentY = (position.z + gridSize.y / 2) / gridSize.y; //算出在哪個格子 int x = Mathf.RoundToInt((gridContX - 1) * percentX); int y = Mathf.RoundToInt((gridContY - 1) * percentY); return grid[x, y]; } //通過一個點尋找周圍的點 public List<Node> GetAroundNode(Node node) { List<Node> aroundNodes = new List<Node>(); for (int i = -1; i <= 1; i++) { for (int j = -1; j <= 1; j++) { //傳進來的點的下標 跳過 if(i == 0 && j == 0) { continue; } int tempX = node.gridX + i; int tempY = node.gridY + j; //判斷有沒有越界 if (tempX >= 0 && tempX < gridContX && tempY >= 0 && tempY < gridContY) { aroundNodes.Add(grid[tempX, tempY]); } } } return aroundNodes; } }
using UnityEngine; using System.Collections; using System.Collections.Generic; public class FindPath_AStar : MonoBehaviour { public Transform startPoint; public Transform endPoint; private Grid grid; // Use this for initialization void Start () { grid = GetComponent<Grid>(); } void Update () { FindPath(startPoint.position, endPoint.position); } // void FindPath(Vector3 startPos, Vector3 endPos) { //開啟列表 List<Node> opentSet = new List<Node>(); //關閉列表 List<Node> closeSet = new List<Node>(); //起點格子 Node startNode = grid.FindWithPosition(startPos); //終點格子 Node endNode = grid.FindWithPosition(endPos); //把起點加入開啟列表 opentSet.Add(startNode); //開始迴圈（開啟列表有值） while (opentSet.Count > 0) { //當前點 Node currentNode = opentSet[0]; //開啟列表中最小的f_Cost for (int i = 0; i < opentSet.Count; i++) { //如果總花費最小，並且離目標點最近 if (opentSet[i].fCost <= currentNode.fCost && opentSet[i].hCost < currentNode.fCost) { currentNode = opentSet[i]; } } //把這個點 點紅 //把當前點從開啟列表刪除 opentSet.Remove(currentNode); //把當前點新增到關閉列表 closeSet.Add(currentNode); //If當前點是終點，跳出迴圈 if (currentNode == endNode) { GetPath(startNode, endNode); return; } //周圍的點 List<Node> around = grid.GetAroundNode(currentNode); //迴圈周圍的點 foreach (Node node in around) { //這個點不能走或者在關閉列表中，跳過這個點 if (!node.canWalk || closeSet.Contains(node)) { continue; } //點開一個紅點，周圍的點會得到一個新的花費g int newCost_g = currentNode.gCost + GetCost(currentNode, node); //比較新花費和原來的花費，誰更小(誰離我們起點近) || 這個點不再開啟列表中 if (newCost_g < node.gCost || !opentSet.Contains(node)) { //替換成新的花費 node.gCost = newCost_g; node.hCost = GetCost(node, endNode); //將這個點（周圍的點裡面的）的父節點設定為當前點（新點開的紅點） node.parent = currentNode; //這個點不再開啟列表中 if (!opentSet.Contains(node)) { opentSet.Add(node); } } } } } //計算花費 int GetCost(Node a, Node b) { //等到兩點之間的一個距離（x方向和y方向） int coutX = Mathf.Abs(a.gridX - b.gridX); int coutY = Mathf.Abs(a.gridY - b.gridY); if(coutX > coutY) { return (coutX - coutY) * 10 + coutY * 14; } else { return (coutY - coutX) * 10 + coutX * 14; } } //得到路徑 void GetPath(Node startNode, Node endNode) { List<Node> path = new List<Node>(); Node temp = endNode; while(temp != startNode) { path.Add(temp); temp = temp.parent; } //列表轉置 path.Reverse(); grid.path = path; } }