02_connecting_grids.md

steps/elevators/portals

python-pathfinding allows you to connect grids. This could be useful to create buildings with multiple storeys that are connected by elevators or stairs or different areas you want to connect with portals.

Lets say we want to connect 2 storey of a building with an elevator:

level0 = [
  [1, 1, 1],
  [1, 0, 0],
  [1, 1, 1]
]
level1 = [
  [1, 1, 1],
  [0, 0, 1],
  [1, 1, 1]
]
# create Grid instances for both level
grid0 = Grid(matrix=level0, grid_id=0)
grid1 = Grid(matrix=level1, grid_id=1)

We can connect a node from one grid to another by defining a connection between the two grids like this:

# elevator up
grid0.node(2, 2).connect(grid1.node(2, 2))
# elevator down
grid1.node(2, 2).connect(grid0.node(2, 2))

Note that we need to do this in both directions if we want to allow the connection to go both ways (otherwise the elevator can only go in one direction, which might be a desired feature).

Because the find_neighbors-function in the finder needs to look up both grids we need to provide both grids to the finder. We can create a "world" that looks up both grids:

  # create world with both grids
world = World({
    0: grid0,
    1: grid1
})

finder = AStarFinder()
path, _ = finder.find_path(grid0.node(2, 0), grid1.node(0, 0), world)

and that gives you the path from the top-right node of the lower grid (0) to the top-left of the upper node using the elevator in the right bottom of both level.

For the whole code take a look at the test_connect_grids.py file in the test-folder