cave_map_generator.lua: limit find_path dimensions to inner board.

[virtualghetto]

find_path last 2 arguments are the dimensions of the map.
If you create 2 chambers and a passage at the bottom edge of the map, the generated path will be impassable because it goes into the border.
This PR makes find_path consider the inner board only for its path calculation.

[CelticMinstrel]

I think the above linked commit should fix this in a cleaner way. Your patch just creates the question of "why -2?" which is confusing.

[virtualghetto]

I think the above linked commit should fix this in a cleaner way. Your patch just creates the question of "why -2?" which is confusing.

Because -1 didn't work either for my patch :)

I just tested your patch and it suffers the same problem.
adding the following to it will fix it without having to mess with the last two parameters of find_path.
or x == params.map_width -1 or y == params.map_height -1

Remember, when a cave map dimensions are given as 20,20,
19,19 would then be the impassable bottom right border corner
and 18,18 is the passable the inner right bottom corner.

[CelticMinstrel]

Yeah, that makes sense. Pretty sure 0 is correct for the left and top border though?

[virtualghetto]

Yes. 0,0 is the top left impassable border corner and 1,1 is the passable inner corner.

This is the map that I tested it on.
It creates four keeps at each corner and it connects each other with a passage along the map edge.

    map_generation=lua
    [generator]
        id="cavegen"
        config_name="Lua Cave Generator"
        create_map = << return wesnoth.require("cave_map_generator").generate_map(...) >>

        village_density=0

        terrain_wall = "Xu"
        terrain_clear = "Uu"
        terrain_keep = "Kud"
        terrain_castle = "Cud"
        terrain_village = "Uu^Vud"

        # Bottom right inside corner is 18,18
        map_width=20
        map_height=20
        [chamber]
            id=mini_01
            x=18
            y=18
            size=1
            [item_location]
                id = 1
                place_castle = yes
            [/item_location]
        [/chamber]
        [chamber]
            id=mini_02
            x=1
            y=18
            size=1
            [item_location]
                id = 2
                place_castle = yes
            [/item_location]
            [passage]
                destination=mini_01
            [/passage]
        [/chamber]
        [chamber]
            id=mini_03
            x=1
            y=1
            size=1
            [item_location]
                id = 3
                place_castle = yes
            [/item_location]
            [passage]
                destination=mini_02
            [/passage]
        [/chamber]
        [chamber]
            id=mini_04
            x=18
            y=1
            size=1
            [item_location]
                id = 4
                place_castle = yes
            [/item_location]
            [passage]
                destination=mini_03
            [/passage]
            [passage]
                destination=mini_01
            [/passage]
        [/chamber]
    [/generator]