title: what is cv::setTo function
body: <p>I have a code written using OpenCV in C++, and this code uses a function setTo. Basically, it is used as:</p>
  
  <pre><code>cv::Mat xx; //prefedined and has some values
  cv::Mat yy; // initially empty
  
  yy.setTo(0,xx);
  </code></pre>
  
  <p>So can you explain what does this setTo means here? Does is put all zero values in yy, or it puts 1 where xx is non-zero and 0 where xx is zero too?</p>