写一段将ply点云文件中的各个点按最小生成树的顺序连成线段的C++代码

以下是将Ply点云文件中的各个点按最小生成树的顺序连成线段的C++代码：

#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <queue>

using namespace std;

struct Point {
    float x, y, z;
};

struct Edge {
    int src, dst;
    float weight;
};

struct Graph {
    vector<Point> points;
    vector<Edge> edges;
};

bool compareEdge(Edge e1, Edge e2) {
    return e1.weight < e2.weight;
}

Graph readPlyFile(string filename) {
    Graph graph;
    ifstream plyFile(filename);
    string line;

    // skip header
    while (getline(plyFile, line)) {
        if (line == "end_header") {
            break;
        }
    }

    // read vertices
    int numVertices;
    plyFile >> line >> numVertices;
    for (int i = 0; i < numVertices; i++) {
        Point p;
        plyFile >> p.x >> p.y >> p.z;
        graph.points.push_back(p);
    }

    // read faces
    int numFaces;
    plyFile >> line >> numFaces;
    for (int i = 0; i < numFaces; i++) {
        int numIndices;
        plyFile >> numIndices;
        vector<int> indices(numIndices);
        for (int j = 0; j < numIndices; j++) {
            plyFile >> indices[j];
        }
        for (int j = 0; j < numIndices - 1; j++) {
            Edge e;
            e.src = indices[j];
            e.dst = indices[j+1];
            e.weight = sqrt(pow(graph.points[indices[j]].x - graph.points[indices[j+1]].x, 2) +
                            pow(graph.points[indices[j]].y - graph.points[indices[j+1]].y, 2) +
                            pow(graph.points[indices[j]].z - graph.points[indices[j+1]].z, 2));
            graph.edges.push_back(e);
        }
        Edge e;
        e.src = indices[numIndices-1];
        e.dst = indices[0];
        e.weight = sqrt(pow(graph.points[indices[numIndices-1]].x - graph.points[indices[0]].x, 2) +
                        pow(graph.points[indices[numIndices-1]].y - graph.points[indices[0]].y, 2) +
                        pow(graph.points[indices[numIndices-1]].z - graph.points[indices[0]].z, 2));
        graph.edges.push_back(e);
    }

    plyFile.close();
    return graph;
}

vector<int> prim(Graph graph) {
    vector<int> mst;
    vector<bool> visited(graph.points.size(), false);
    priority_queue<pair<float, int>, vector<pair<float, int>>, greater<pair<float, int>>> pq;

    // start from first point
    visited[0] = true;
    for (Edge e : graph.edges) {
        if (e.src == 0) {
            pq.push(make_pair(e.weight, e.dst));
        }
        if (e.dst == 0) {
            pq.push(make_pair(e.weight, e.src));
        }
    }

    while (!pq.empty()) {
        pair<float, int> p = pq.top();
        pq.pop();
        if (visited[p.second]) {
            continue;
        }
        visited[p.second] = true;
        mst.push_back(p.second);
        for (Edge e : graph.edges) {
            if ((e.src == p.second && !visited[e.dst]) ||
                (e.dst == p.second && !visited[e.src])) {
                pq.push(make_pair(e.weight, (e.src == p.second) ? e.dst : e.src));
            }
        }
    }

    return mst;
}

int main() {
    Graph graph = readPlyFile("input.ply");
    vector<int> mst = prim(graph);
    ofstream outputFile("output.ply");
    outputFile << "ply" << endl 
                << "format ascii 1.0" << endl 
                << "element vertex " << mst.size() << endl 
                << "property float x" << endl 
                << "property float y" << endl 
                << "property float z" << endl 
                << "element edge " << mst.size()-1 << endl 
                << "property int vertex1" << endl 
                << "property int vertex2" << endl 
                << "end_header" << endl;
    for (int i : mst) {
        outputFile << graph.points[i].x << " " << graph.points[i].y << " " << graph.points[i].z << endl;
    }
    sort(mst.begin(), mst.end());
    for (int i = 0; i < mst.size()-1; i++) {
        outputFile << i << " " << i+1 << endl;
    }
    outputFile.close();
    return 0;
}

该代码先通过readPlyFile函数读取Ply点云文件中的信息，将点存储在points中，将每个面中相邻的点的信息转换成边存储在edges中，并计算每条边的权值。然后通过prim函数求出最小生成树，并将最小生成树中的点和边按Ply文件格式输出到文件中