ROS学习笔记(十九)：Markers: Points and Lines (C++)

1.Intro

在“标记：基本形状”中，您学习了如何使用可视化标记将简单形状发送到rviz。 您不仅可以发送简单的形状，而且本教程将向您介绍POINTS，LINE_STRIP和LINE_LIST标记类型。 有关类型的完整列表，请参见“标记显示”页面。

2.Using Points, Line Strips, and Line Lists

POINTS，LINE_STRIP和LINE_LIST标记都使用visualization_msgs / Marker消息的点成员。POINTS类型在添加的每个点处放置一个点。 LINE_STRIP类型将每个点用作一组连接的线中的点，其中点0连接到点1、1、2、2、3等。LINE_LIST类型在每对点中创建未连接的线，即点 0至1、2至3等。

2.1 The Code

30 #include <ros/ros.h> 31 #include <visualization_msgs/Marker.h> 32 33 #include <cmath> 34 35 int main( int argc, char** argv ) 36 { 37 ros::init(argc, argv, "points_and_lines"); 38 ros::NodeHandle n; 39 ros::Publisher marker_pub = n.advertise<visualization_msgs::Marker>("visualization_marker", 10); 40 41 ros::Rate r(30); 42 43 float f = 0.0; 44 while (ros::ok()) 45 { 46 47 visualization_msgs::Marker points, line_strip, line_list; 48 points.header.frame_id = line_strip.header.frame_id = line_list.header.frame_id = "/my_frame"; 49 points.header.stamp = line_strip.header.stamp = line_list.header.stamp = ros::Time::now(); 50 points.ns = line_strip.ns = line_list.ns = "points_and_lines"; 51 points.action = line_strip.action = line_list.action = visualization_msgs::Marker::ADD; 52 points.pose.orientation.w = line_strip.pose.orientation.w = line_list.pose.orientation.w = 1.0; 53 54 55 56 points.id = 0; 57 line_strip.id = 1; 58 line_list.id = 2; 59 60 61 62 points.type = visualization_msgs::Marker::POINTS; 63 line_strip.type = visualization_msgs::Marker::LINE_STRIP; 64 line_list.type = visualization_msgs::Marker::LINE_LIST; 65 66 67 68 // POINTS markers use x and y scale for width/height respectively 69 points.scale.x = 0.2; 70 points.scale.y = 0.2; 71 72 // LINE_STRIP/LINE_LIST markers use only the x component of scale, for the line width 73 line_strip.scale.x = 0.1; 74 line_list.scale.x = 0.1; 75 76 77 78 // Points are green 79 points.color.g = 1.0f; 80 points.color.a = 1.0; 81 82 // Line strip is blue 83 line_strip.color.b = 1.0; 84 line_strip.color.a = 1.0; 85 86 // Line list is red 87 line_list.color.r = 1.0; 88 line_list.color.a = 1.0; 89 90 91 92 // Create the vertices for the points and lines 93 for (uint32_t i = 0; i < 100; ++i) 94 { 95 float y = 5 * sin(f + i / 100.0f * 2 * M_PI); 96 float z = 5 * cos(f + i / 100.0f * 2 * M_PI); 97 98 geometry_msgs::Point p; 99 p.x = (int32_t)i - 50; 100 p.y = y; 101 p.z = z; 102 103 points.points.push_back(p); 104 line_strip.points.push_back(p); 105 106 // The line list needs two points for each line 107 line_list.points.push_back(p); 108 p.z += 1.0; 109 line_list.points.push_back(p); 110 } 111 112 113 marker_pub.publish(points); 114 marker_pub.publish(line_strip); 115 marker_pub.publish(line_list); 116 117 r.sleep(); 118 119 f += 0.04; 120 } 121 }

2.2 Viewing the Markers

设置rviz的方法与上一教程中的方法相同，如下所示： 编辑using_markers包中的CMakeLists.txt文件，并将其添加到底部：

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

then,

$ catkin_make

then,

$ rosrun rviz rviz & $ rosrun using_markers points_and_lines

您应该看到一个看起来像这样的旋转螺旋：