title: how to find a point is on left or right side of line using Python and DLib?
body: <p>I am trying to find an existing API in Dlib/OpenCV/Numpy/Scipy to find out a point is on the left side or right side of the line.</p>
  <pre class="lang-py prettyprint-override"><code>import dlib
  a = dlib.point(0, 0)
  b = dlib.point(20, 20)
  line = dlib.line(a, b)
  dlib.distance_to_line(line, dlib.point((-50, 4))) # provides absolute distance. 
  </code></pre>
  <h3>Searching Solution</h3>
  <p>A simple API that tells it is left/right side of a line.</p>
  <pre><code>example 
  dlib.where_is_the_point(line, dlib.point((-50, 4)) # if returns negative means left side.
  </code></pre>
  <h3>My current solution</h3>
  <p>I wrote a math to find a point is left side or right side. So below functions returns a <code>d</code>, Based on sign of <code>d</code> I can tell it is left or right. Kind of hard coded way, not liking below solution.</p>
  <pre><code>    def where_it_is(self, target: Point):
          d = (target.x - self.p1[0]) * (self.p2[1] - self.p1[1]) - (target.y - self.p1[1]) * (self.p2[0] - self.p1[0])
          return d
  </code></pre>