title: Add text next to a Point in PCL visualizer
body: <p>I have an application where I successfully plot 2D laser range data from a LiDAR in real-time and run PCL's Euclidean clustering algorithm to paint those cluster points in a different color. I would however like to add a text next to each detected cluster and tell its distance from the sensor. I do have the coordinate of the centroid point of each detected cluster but when I try to use the addText:</p>
  
  <p>bool pcl::visualization::PCLVisualizer::<strong>addText</strong> (const std::string &amp;    text, int xpos, int ypos,double r,double g,double b,const std::string &amp; id = "")</p>
  
  <p>text: Text to be printed in window </p>
  
  <p>xpos: position in x</p>
  
  <p>ypos: position in y</p>
  
  <p>r: red</p>
  
  <p>g: green</p>
  
  <p>b: blue</p>
  
  <p>id: Text ID tag</p>
  
  <p>It seems like the function addText() puts the text in on PIXEL x- and y-values in stead of real-world values (meters). However, PCLs other method such as "addPoint()", addCircle() etc are indeed placing the data based on real world measurements.</p>
  
  <p><strong>Does anyone have experience with transforming spatial coordinates to pixels in PCL visualizer, or have successfully plotted text in other ways?</strong></p>
  
  <p>Below is a screenshot of my application. Clusters are drawn in red with a white circle around the centroid. At the bottom left I'm printing the distance of each cluster. As can be seen they are just stacked on top of each other instead of being added on top of its own white circle.</p>
  
  <p>Thankful for any help</p>
  
  <p>regards
  <a href="https://i.stack.imgur.com/ZHwSm.png" rel="nofollow noreferrer">Screenshot</a></p>