title: Determine if a point is within a section of a sphere surface
body: <p>Hi i'm starting to work with webGL using Three.js and I need to detect if a click on a sphere is within a certain section of it's surface.</p>
  
  <p>Currently i can detect if the sphere was clicked and get the coords of the point clicked. Now what i need is to detect if that click was in a certain region of that sphere, based on a array of 3D points from that sphere (another suggestion is ok).</p>
  
  <p>The sphere is in the center point, and the point is garrantied to be on the surface of the sphere. Now i need to calculate if it's just within a section section. Any suggestions? My problem seams to be more mathematical. 
  Also i prefere a generic way to do this because the sections may be just a triangle or may be more complex figures.</p>