title: A* pathfinding algorithm against walls
body: <p>So i'm making a game that looks like the following: 
  <a href="https://gyazo.com/9d72dd5a9ac29f059ed474376f9679a2" rel="nofollow noreferrer">https://gyazo.com/9d72dd5a9ac29f059ed474376f9679a2</a></p>
  
  <p>Now i'm trying to implement the a* algorithm to get the red tank to the green tank. However looking at existing code, (mainly looking at the pathfinding on cokeandcode.com) they have been implemented using grid based maps.</p>
  
  <p>My game is grid based, however the walls of the maze are made from the edges of each 'square' of the grid, with some walls up and some down to make the maze. The following link may illustrate this better:</p>
  
  <p><a href="https://gyazo.com/afefe7d2bdc2b5f02bf546090459f539" rel="nofollow noreferrer">https://gyazo.com/afefe7d2bdc2b5f02bf546090459f539</a></p>
  
  <p>My question is, how would I implement the pathfinding algorithm from the cokeandcode site if my map is not entirely grid based. The algorithm knows if a path is blocked if a square of the grid is not passable, however in my game, all squares are passable. It's the walls of each square that is not passable.</p>