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README.md

lua-star

Build Status Lua-star is a pure Lua A* path-finding library.

lua star example screenshot

Quick Start

Easy to use, it will make you more attractive and you feel sensual doing so.

local luastar = require("lua-star")

function positionIsOpenFunc(x, y)
    -- should return true if the position is open to walk
    return mymap[x][y] == walkable
end

local path = luastar:find(width, height, start, goal, positionIsOpenFunc, useCache)

path will be false if no path was found, otherwise it contains a list of points that travel from start to goal:

if path then
    for _, p in ipairs(path) do
        print(p.x, p.y)
    end
end

Lua star does not care how your map data is arranged, it simply asks you if the map position at x,y is walkable via a callback.

width and height is your map size.

start and goal are tables with at least the x and y keys.

local start = { x = 1, y = 10 }
local goal = { x = 10, y = 1 }

positionIsOpenFunc(x, y) is a function that should return true if the position is open to walk.

useCache is optional and defaults to false when not given. If you have a map that does not change, caching can give a speed boost.

If at any time you need to clear all cached paths:

luastar:clearCached()

Requirements

For running unit tests:

These commands are for apt-based systems, please adapt to them as needed.

sudo apt-get install luarocks
sudo luarocks install busted

Unit testing is done with busted, the .busted config already defines everything, so simply run:

busted

Performance

There is a performance measurement tool in tests/performance.lua, it calculates the average time to find a path on a large, random map.

# copy the lib to tests
$ cp ../src/lua-star.lua .

# measure performance
$ lua performance.lua
Running with seed 1540584306
Building a map of 3000x3000...
Precalculating 6000 random start/goal positions...
Finding 1000 paths...
    Done in 16.37 seconds.
    That is 0.0164 seconds, or 16 milliseconds, per path.
    The map has 9.0 million locations, with about 65% open space.

Example

There is an interactive example that can be run with Love.

License

See the file LICENSE

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Easy A* path finding for Lua

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