blondeburrito / hexagonal_pathfinding_astar Goto Github PK

In the event that two distinct hexagon grids are merged into the same data set (think of two islands separated by an ocean where the ocean isn't made of traversable hexagons) and the start point is in one set and the end point is in the other set then no path will be found as there are no neighbours bridging the two sets. It will either panic or get stuck in an infinite loop.

This can be resolved by amending the end of the A-Star calculation to check the size of the queue of nodes to be processed. If queue.len() == 0 then it means all nodes have been exhausted and there is no path.

Rather than returning a Vec to the user an Option should instead be returned. Where None indicates that no path could be found and Some will contain a Vec of the best path.

Node positions must be smaller than i32::MAX/2 and greater than i32::MIN/2.

Should validation be added to the library to inform the user if they violate these bounds?

See the hex-spiral crate.

Stack Exchange

• Converting Between Spiral Honeycomb Mosaic And Axial Hex Coordinate
• Is There an Easy Way to Number a Hexagonal Spiral?

Currently two Offset hexagon orientations have been included:

• flat top, odd columns shifted up

             _______
            /       \
    _______/  (1,1)  \_______
   /       \         /       \
  /  (0,1)  \_______/  (2,1)  \
  \         /       \         /
   \_______/  (1,0)  \_______/
   /       \         /       \
  /  (0,0)  \_______/  (2,0)  \
  \         /       \         /
   \_______/         \_______/

• flat top , odd columns shifted down

    _______           _______
   /       \         /       \
  /  (0,1)  \_______/  (2,1)  \
  \         /       \         /
   \_______/  (1,1)  \_______/
   /       \         /       \
  /  (0,0)  \_______/  (2,0)  \
  \         /       \         /
   \_______/  (1,0)  \_______/
           \         /
            \_______/

There are another two styles to creating a hexagon grid:

• Pointy top, odd columns shifted down
• Pointy top, odd column shifted up

Which should be codified into fn expand_neighrbor_nodes() so paths in pointy-topped grids can be found