RVIZ（一）:发送基本形状

介绍：

与其他显示器不同，标记显示器允许您在rviz中可视化数据，而无需了解有关解释该数据的任何信息。相反，原始对象通过visualization_msgs / Marker消息发送到显示器，使您可以显示箭头，方框，球体和线条等内容。

本教程将向您展示如何发送四种基本形状（盒子，球体，圆柱体和箭头）。我们将创建一个程序，每秒发送一个新标记，用不同的形状替换最后一个标记。

第一步：新建一个ros工作包

mkdir -p ~/catkin_2/src  

catkin_create_pkg using_markers roscpp visualization_msgs  

cd ~/catkin_2
catkin_make

第二步：编写basic_shapes.cpp文件

#include
#include            //可视化

int main( int argc, char** argv )
{
  //初始化ROS，幷且创建一个ROS::Publisher 在话题visualization_marker上面
  ros::init(argc, argv, "basic_shapes");
  ros::NodeHandle n;
  ros::Rate r(1);
  ros::Publisher marker_pub = n.advertise("visualization_marker", 1);

  // Set our initial shape type to be a cube
  // 初始化形状为立方体
  uint32_t shape = visualization_msgs::Marker::CUBE;

  while (ros::ok())
  {
    //实例化一个Marker
    visualization_msgs::Marker marker;

    // Set the frame ID and timestamp.  See the TF tutorials for information on these.
    // 设置frame ID 和 时间戳
    marker.header.frame_id = "/my_frame";
    marker.header.stamp = ros::Time::now();

    // Set the namespace and id for this marker.  This serves to create a unique ID
    // Any marker sent with the same namespace and id will overwrite the old one
    // 为这个marker设置一个独一无二的ID，一个marker接收到相同ns和id就会用新的信息代替旧的
    marker.ns = "basic_shapes";
    marker.id = 0;

    // Set the marker type.  Initially this is CUBE, and cycles between that and SPHERE, ARROW, and CYLINDER
    // 设置marker类型，初始化是立方体。将进行循环
    marker.type = shape;

    // Set the marker action.  Options are ADD, DELETE, and new in ROS Indigo: 3 (DELETEALL)
    marker.action = visualization_msgs::Marker::ADD;

    // Set the pose of the marker.  This is a full 6DOF pose relative to the frame/time specified in the header
    // 设置marker的位置
    marker.pose.position.x = 0;
    marker.pose.position.y = 0;
    marker.pose.position.z = 0;
    marker.pose.orientation.x = 0.0;
    marker.pose.orientation.y = 0.0;
    marker.pose.orientation.z = 0.0;
    marker.pose.orientation.w = 1.0;

    // Set the scale of the marker -- 1x1x1 here means 1m on a side
    // 设置marker的大小
    marker.scale.x = 1.0;
    marker.scale.y = 1.0;
    marker.scale.z = 1.0;

    // Set the color -- be sure to set alpha to something non-zero!
    // 设置marker的颜色
    marker.color.r = 0.0f;
    marker.color.g = 1.0f;
    marker.color.b = 0.0f;
    marker.color.a = 1.0;

    //取消自动删除
    marker.lifetime = ros::Duration();

    // Publish the marker
    // 必须有订阅者才会发布消息
    while (marker_pub.getNumSubscribers() < 1)
    {
      if (!ros::ok())
      {
        return 0;
      }
      ROS_WARN_ONCE("Please create a subscriber to the marker");
      sleep(1);
    }
    marker_pub.publish(marker);

    // Cycle between different shapes
    // 连续改变形状
    switch (shape)
    {
    case visualization_msgs::Marker::CUBE:
      shape = visualization_msgs::Marker::SPHERE;
      break;
    case visualization_msgs::Marker::SPHERE:
      shape = visualization_msgs::Marker::ARROW;
      break;
    case visualization_msgs::Marker::ARROW:
      shape = visualization_msgs::Marker::CYLINDER;
      break;
    case visualization_msgs::Marker::CYLINDER:
      shape = visualization_msgs::Marker::CUBE;
      break;
    }

    r.sleep();
  }
}

第三步：在Cmakelist.txt文件中添加依赖关系

add_executable(basic_shapes src/basic_shapes.cpp)
target_link_libraries(basic_shapes ${catkin_LIBRARIES})

第四步：编译

catkin_make

source catkin_2/devel/setup.bash

第五步：运行

（一）打开roscore

rosrun roscore

（二）运行编写的发布器

rosrun using_markers basic_shapes

（三）重置rviz，运行rviz

rosmake rviz

rosrun rviz rviz

（四）在rviz中设置

添加Marker栏

且将Global Options中的Fixed Fram改为my_frame

即可得到如下图像