我一直在试图实施A *数周,所以敌人可以在我的游戏中追逐一名玩家,但我无法让它工作。我整个周末都在努力研究它,甚至结束了大部分研究并重新编写它。我可以绘制从起始位置到目标的路径,但我无法追溯到实际写下路径的路径。我从SFML使用Vector2f(有序对的浮点数)和Sprite,但所有的代码都非常简单,所以你不需要了解它。如何在C++中使用A *追溯路径?
编辑:问题是Node.cameFrom。出于某种原因,它除了墙壁之外什么都不会。
这里的Node.h
#ifndef NODE_H
#define NODE_H
#include <SFML/Graphics.hpp>
using namespace sf;
class Node {
public:
Vector2f pos;
// Distance traveled already to reach node
int level;
// Level + estimated dist to goal
int priority;
Node *cameFrom;
Node(Vector2f npos, int lv, Vector2f dest, Node *cf=nullptr);
bool operator == (const Node &nhs) const {
return nhs.priority == priority;
}
};
#endif // NODE_H
Node.cpp
#include "Node.h"
#include <SFML/Graphics.hpp>
#include <math.h>
#include <iostream>
using namespace std;
using namespace sf;
int estimatedDist(Vector2f pos, Vector2f dest) {
return abs(dest.x - pos.x) + abs(dest.y - pos.y);
}
Node::Node(Vector2f npos, int lv, Vector2f dest, Node *cf) {
cameFrom = cf;
level = lv;
pos = npos;
priority = level + estimatedDist(pos, dest);
}
Enemy.cpp pathfind功能
bool occupies(Vector2f pos, vector<Wall> walls) {
for (unsigned w = 0; w < walls.size(); w++) {
if (walls.at(w).collisionBox.getGlobalBounds().contains(pos.x * 32, pos.y * 32)) {
return true;
}
}
return false;
}
bool nFind(Node n, vector<Node> nodes) {
for (unsigned i = 0; i < nodes.size(); i++) {
if (nodes.at(i).pos == n.pos) {
return true;
}
}
return false;
}
void Enemy::pathFind(Vector2f dest, vector<Wall> walls) {
char fullMap[32][22];
vector<Node> openSet;
vector<Node> closedSet;
int xStart, yStart;
for (unsigned y = 0; y < 22; y++) {
for (unsigned x = 0; x < 32; x++) {
if (sprite.getGlobalBounds().top >= y * 32 && sprite.getGlobalBounds().top <= (y + 1) * 32) {
if (sprite.getGlobalBounds().left >= x * 32 && sprite.getGlobalBounds().left <= (x + 1) * 32) {
xStart = x;
yStart = y;
}
} if (occupies(Vector2f(x, y), walls)) {
fullMap[x][y] = '2';
} else {
fullMap[x][y] = ' ';
}
}
}
fullMap[int(dest.x)][int(dest.y)] = 'D';
Node *current = new Node(Vector2f(xStart, yStart), 0, dest);
fullMap[int(current->pos.x)][int(current->pos.y)] = '2';
openSet.push_back(*current);
while (openSet.size() > 0) {
sort(openSet.begin(), openSet.end(), sortByPriority());
*current = openSet.front();
if (current->pos == dest) {
cout << "We gots it ";
for (unsigned y = 0; y < 22; y++) {
for (unsigned x = 0; x < 32; x++) {
if (occupies(Vector2f(x, y), walls)) {
fullMap[x][y] = '2';
} else {
fullMap[x][y] = ' ';
}
}
}
while (current->cameFrom) {
fullMap[int(current->pos.x)][int(current->pos.y)] = 'P';
current = current->cameFrom;
for (unsigned y = 0; y < 22; y++) {
for (unsigned x = 0; x < 32; x++) {
cout << fullMap[x][y];
}
cout << endl;
}
cout << endl;
} for (unsigned y = 0; y < 22; y++) {
for (unsigned x = 0; x < 32; x++) {
cout << fullMap[x][y];
}
cout << endl;
}
cout << endl;
return;
}
openSet.erase(remove(openSet.begin(), openSet.end(), *current), openSet.end());
closedSet.push_back(*current);
fullMap[int(current->pos.x)][int(current->pos.y)] = '2';
vector<Node> neighbors;
neighbors.push_back(Node(Vector2f(current->pos.x - 1, current->pos.y - 1), current->level + 1, dest));
neighbors.push_back(Node(Vector2f(current->pos.x, current->pos.y - 1), current->level + 1, dest));
neighbors.push_back(Node(Vector2f(current->pos.x + 1, current->pos.y - 1), current->level + 1, dest));
neighbors.push_back(Node(Vector2f(current->pos.x + 1, current->pos.y), current->level + 1, dest));
neighbors.push_back(Node(Vector2f(current->pos.x + 1, current->pos.y + 1), current->level + 1, dest));
neighbors.push_back(Node(Vector2f(current->pos.x, current->pos.y + 1), current->level + 1, dest));
neighbors.push_back(Node(Vector2f(current->pos.x - 1, current->pos.y + 1), current->level + 1, dest));
neighbors.push_back(Node(Vector2f(current->pos.x - 1, current->pos.y), current->level + 1, dest));
for (unsigned i = 0; i < neighbors.size(); i++) {
if (nFind(neighbors.at(i), closedSet) ||
neighbors.at(i).pos.x > 22 ||
neighbors.at(i).pos.y > 32 ||
neighbors.at(i).pos.x < 0 ||
neighbors.at(i).pos.y < 0 ||
occupies(neighbors.at(i).pos, walls)) {
continue;
} if (!nFind(neighbors.at(i), openSet)) {
openSet.push_back(neighbors.at(i));
}
neighbors.at(i).cameFrom = current;
}
}
}
实际问题是什么?请提供[最小,完整和可验证示例](http://stackoverflow.com/help/mcve)。 – zett42
这个问题没有多大意义 - 如果你已经通过编程获得了路径,那么就按照相反的顺序给它,以获得相反的路径 –
@ M.M这是我的问题,我无法让它工作。 – Merle