title: Intersection between Rectangle and a Circle sector in libgdx
body: <p>I am programming a game using libgdx. For the Enemies i want to write a simple AI. This AI should track the Player if he was in the field of Vision once. The field of Vision is a circle sector or 2d cone. What would be the most efficient way to reach this? I have allready read the following:
  <a href="https://stackoverflow.com/questions/13652518/efficiently-find-points-inside-a-circle-sector">Point in circle sector</a></p>
  
  <p>I could use this with every Corner Point of my Player but i also have the field of Vision given with direction and angle (sector between <code>direction - angle/2</code> to <code>direction + angle/2</code>).
  The angle won't be over 180 (as this would be a problem for the algorithm). Would it be a Problem to calculate the Vectors for start and end of sector for every enemie in the game? What would be the best solution and how can i calculate the Vectors out of the given direction and angle?</p>