title: Finding which region contains a point based on coordinates
body: <p>I have 4 points that form some quadrilateral. The lines can't cross or anything like that, it should be a square, rectangle, rhombus, parallelogram, etc.</p>
  
  <p>The lines that connect them break the field into 9 regions. With a square, it would look like a tic-tac-toe board (#), but with other shapes the lines will be at angles.</p>
  
  <p>A point falls randomly into this 9-region field. I know the coordinates of the random point, as well as the coordinates of the quadrilateral's 4 corners.</p>
  
  <p>Is there any way I can find which field contains the point <strong>without using the equations of the lines</strong>?</p>
  
  <p>I'm basically looking for something like</p>
  
  <pre><code>if(p.x &gt; q1.x &amp;&amp; p.x &lt; q4.x &amp;&amp; p.y &lt; q3.y) {
      //It's in the top left region
  }
  etc
  </code></pre>
  
  <p>I'm thinking that this isn't possible when using sloped lines (rather than a square/rectangle) without solving the line equations. But I thought I'd run it by the math guys first. THANKS!</p>