ros 中使用Visualization::marker,举个例子

在ROS中，Visualiztion::marker是用于在RViz中可视化数据的常用工具之一。下面是一个简单的例子：

假设我们有一个名为“/my_marker”的话题，我们想在RViz中显示一个立方体，我们可以使用以下代码：

#include <ros/ros.h>
#include <visualization_msgs/Marker.h>

int main( int argc, char** argv )
{
  ros::init(argc, argv, "my_marker_publisher");
  ros::NodeHandle n;
  ros::Publisher marker_pub = n.advertise<visualization_msgs::Marker>("my_marker", 1);

  // Set the frame ID and timestamp.  See the TF tutorials for information on these.
  visualization_msgs::Marker marker;
  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
  marker.ns = "basic_shapes";
  marker.id = 0;

  // Set the marker type.  Initially this is CUBE, and cycles between that and SPHERE, ARROW, and CYLINDER
  marker.type = visualization_msgs::Marker::CUBE;

  // Set the pose of the marker.  This is a full 6DOF pose relative to the frame/time specified in the header
  marker.pose.position.x = 1;
  marker.pose.position.y = 1;
  marker.pose.position.z = 1;
  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
  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!
  marker.color.r = 0.0f;
  marker.color.g = 1.0f;
  marker.color.b = 0.0f;
  marker.color.a = 1.0;

  marker.lifetime = ros::Duration();

  // Publish the marker
  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);

  ros::spinOnce();
  return 0;
}

这个例子中，我们创建了一个立方体的visualization_msgs::Marker消息，并将其发布到“/my_marker”话题上。在RViz中，我们可以通过添加一个“Marker”显示来查看它。