Gazebo Callback没有开火

Question

我正在尝试编写一个小型库来连接Gazebo和Python（我尝试使用pygazebo库并没有成功）。我试图从相机获取输出并找到April Tags并将位置数据存储在类变量中，使用用SWIG包装的C ++代码在Python中使用。我有一个独立的C ++应用程序打印这些数据，但我无法让它在一个类中工作。从我的测试线sub = node->Subscribe(IMAGE_TOPIC, &april::callback, this);可能是问题。代码包含在下面。

gazeboApril.cpp

#include "gazeboApril.hpp"

april::april(void) {
    this->tag_size = (0.3 * (8.0 / 10.0)) / 2.0;
    apriltag_family_t *tf = tag36h11_create();
    this->td = apriltag_detector_create();
    apriltag_detector_add_family(this->td, tf);
    gazebo::client::setup();
    gazebo::transport::NodePtr node(new gazebo::transport::Node());
    gazebo::transport::SubscriberPtr sub;
    node->Init();
    sub = node->Subscribe(IMAGE_TOPIC, &april::callback, this);
}

void april::callback(ConstImageStampedPtr &msg) {
    int width;
    int height;
    char *data;

    width = (int) msg->image().width();
    height = (int) msg->image().height();
    data = new char[msg->image().data().length() + 1];

    memcpy(data, msg->image().data().c_str(), msg->image().data().length());
    cv::Mat image(height, width, CV_8UC3, data);

    cv::Mat gray;
    cv::cvtColor(image, gray, cv::COLOR_BGR2GRAY);
    image_u8_t im = { .width = gray.cols,
        .height = gray.rows,
        .stride = gray.cols,
        .buf = gray.data
    };
    zarray_t *detections = apriltag_detector_detect(td, &im);
    apriltag_detection *det;
    this->id.resize(zarray_size(detections));
    this->d.resize(zarray_size(detections));
    this->theta.resize(zarray_size(detections));
    for (int i = 0; i < zarray_size(detections); i++) {
        zarray_get(detections, i, &det);
        this->id.at(i) = det->id;
        matd_t *pose = homography_to_pose(det->H, -1108.77, 1108.77, 1280 / 2, 720 / 2);
        this->d.at(i) = this->tag_size * sqrt(pow(MATD_EL(pose, 0, 3), 2) + pow(MATD_EL(pose, 2, 3), 2));
        this->theta.at(i) = atan2(MATD_EL(pose, 0, 3), MATD_EL(pose, 2, 3));
    }
    delete data;
}

void april::stop(void) {
    gazebo::client::shutdown();
}

gazeboApril.hpp

#include <vector>

#include <gazebo/gazebo_client.hh>
#include <gazebo/msgs/msgs.hh>
#include <gazebo/transport/transport.hh>

#include <opencv2/opencv.hpp>

#include "apriltag.h"
#include "tag36h11.h"
#include "common/homography.h"

#pragma once

#define IMAGE_TOPIC "/gazebo/default/pioneer3at/camera/link/camera/image"

class april {
public:
    april(void);
    void stop(void);
public:
    void callback(ConstImageStampedPtr &msg);
public:
    std::vector<int> id;
    std::vector<double> d;
    std::vector<double> theta;
protected:
    apriltag_detector_t *td;
    double tag_size;
};

gazeboApril.i

%module gazeboApril
%include "typemaps.i"
%include "std_vector.i"
namespace std {
    %template(IntVector) vector<int>;
    %template(DoubleVector) vector<double>;
};
%{
#include <Python.h>
#include "gazeboApril.hpp"
%}
%naturalvar april::id;
%naturalvar april::d;
%naturalvar april::theta;
%include "gazeboApril.hpp"

Answer 1

你需要使Node::Subscribe的返回值成为局部变量并保留它。

在调用SubscribePtr的析构函数之前，您只能保留对该主题的订阅。在您的示例中，sub变量是构造函数的本地变量，因此您只要在构造函数离开时就取消订阅。