title: Making a Ball drop over the Edge of a Plane
body: <p>I writing a program in C++ using OpenGL/win32 of a ball that bounces when it's dropped from a height above either of the planes/platforms you see below.</p>
  
  <p>I use <a href="http://en.wikipedia.org/wiki/Circle_of_a_sphere#Sphere-plane_intersection" rel="nofollow noreferrer">plane sphere intersection</a> and <a href="http://www.edenwaith.com/products/pige/tutorials/collision.php" rel="nofollow noreferrer">plane-sphere collision</a> to make the ball fall/bounce accordingly (<strong>not</strong> a bounding box).</p>
  
  <p>I'm now hoping to make the ball roll over the edge of the plane like it would in reality if more than half the ball is over the edge.</p>
  
  <p>I was wondering what other forces I would need to simulate and how that can be implemented? I currently only simulate gravity based on the y-axis and a velocity for the return of the bounce.</p>
  
  <p>As things stand, the ball can go right to the edge of the plane and as it slowly moves away, it will drop a little the further right it goes, but still remains on the platform until there's no-longer a collision. (I hope that makes sense). I've screen shot these images to try to show it:</p>
  
  <p><strong>On the edge, before it should fall:</strong></p>
  
  <p><img src="https://i.stack.imgur.com/sgji9.jpg" alt="On edge"></p>
  
  <p><strong>Still on edge, but should be falling (although dropped slightly):</strong></p>
  
  <p><img src="https://i.stack.imgur.com/DnD95.jpg" alt="Still on edge"></p>
  
  <p><strong>Drops only after the far left of the sphere is no-longer touching the plane:</strong></p>
  
  <p><img src="https://i.stack.imgur.com/qbJOu.jpg" alt="Drops"></p>