text: // Copyright © 2014 QuarksCode.  MIT License - see http://opensource.org/licenses/MIT or LICENSE.md file
  // Original Author:  aeoril
  //
  // angle2d.js - angle from -PI .. PI counterclockwise increasing for 2-dimensional vector wrt positive x axis
  
  'use strict';
  
  function angle2d(vec) {
      return Math.atan2(vec[1], vec[0]);
  }
  
  module.exports = angle2d;
  