How do you access the individual vertices inside of a pcl::PolygonMesh? - c++

Question

I'm currently using visual studio 2022
I'm using vcpkg pcl:x64 library install.
pcl version: 1.9.1-12
I'm expecting to be able to access 3 vertices per polygon.
Unfortunately, I can't seem to access the vertices associated with each triangle.
#include <Eigen/Dense>
#include <pcl/common/io.h>
#include <pcl/filters/extract_indices.h>
#include <pcl/filters/passthrough.h>
#include <pcl/point_cloud.h>
#include <pcl/point_types.h>
#include <pcl/PolygonMesh.h>
#include <pcl/TextureMesh.h>
int main
{
pcl::PolygonMesh mesh;
pcl::io::loadPolygonFileOBJ("pathtomesh.meshfile.obj", mesh);
pcl::PointXYZ v = mesh.polygons[0].vertices[0];
}
the error i recieve is:
no suitable constructor exists to convert from "boost::random::seed_seq::result_type" to "pcl::PointXYZ"

Answer 1

It seems as though vertices is an unsigned int and not a pcl::PointXYZ. This is kinda weird to me because I was expecting a double or a floating point to store the vertices coordinates. It turns out that mesh.polygons[0].vertices[0] returns the indices of each point in the mesh that are stored in the point cloud. So i was able to find the points that the function mesh.polygons[0].vertices[0] were pointing at by using converting the mesh to a pcl::PointCloudpcl::PointXYZ and putting the indexes into that function.
pcl::PolygonMesh mesh;
pcl::io::loadPolygonFileOBJ("D:\\testOBJs\\cube.obj", mesh);
pcl::PointCloud<pcl::PointXYZ>::Ptr allVertices(new pcl::PointCloud<pcl::PointXYZ>);
pcl::fromPCLPointCloud2(mesh.cloud, *allVertices);
std::cout << "All Vertices" << std::endl;
for (int i = 0; i < allVertices->size(); i++)
{
std::cout << std::to_string(i) + " " << allVertices->points[i] << std::endl;
}
std::cout << "All Polygons" << std::endl;
for (int i = 0; i < mesh.polygons.size(); i++)
{
std::cout << std::endl;
std::cout << mesh.polygons[i].vertices[0] << std::endl;
std::cout << mesh.polygons[i].vertices[1] << std::endl;
std::cout << mesh.polygons[i].vertices[2] << std::endl;
std::cout << std::endl;
}