https://github.com/xiejiangzhi/astar

A star path finder for Lua
https://github.com/xiejiangzhi/astar

astar-algorithm lua path-finder

Last synced: about 1 month ago
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A star path finder for Lua

• Host: GitHub
• URL: https://github.com/xiejiangzhi/astar
• Owner: xiejiangzhi
• License: mit
• Created: 2020-03-23T12:19:05.000Z (over 4 years ago)
• Default Branch: master
• Last Pushed: 2023-09-25T05:58:44.000Z (about 1 year ago)
• Last Synced: 2024-08-02T06:16:10.544Z (4 months ago)
• Topics: astar-algorithm, lua, path-finder
• Language: Lua
• Size: 189 KB
• Stars: 11
• Watchers: 2
• Forks: 4
• Open Issues: 1
• Metadata Files:
  • Readme: readme.md
  • License: LICENSE

Awesome Lists containing this project

• awesome-love2d - astar - An other A* library. Any map (grid, point, mesh or infinite map) and support path cost. (AI)

README

        
AStar

========

An other A* library. You can use the node or map mode you like(gird, point, mesh or infinite map).

The library don't need to init a map and don't care the size of your map.

We just tell the algo how to get node, neighbors and estimate cost.

Base algorithm logic referenced [a-star-lua](https://github.com/lattejed/a-star-lua)

![img](./example.png)

## Use

A example for grid map

```lua

local AStar = require 'astar'

local map = {}

local cached_nodes = {}

-- Node must be able to check if they are the same

-- Cannot directly return different tables for the same coord

-- The library doesn't change nodes, so you able to reuse your node or create a C struct for faster

local function get_node(x, y)

  local row = cached_nodes[y]

  if not row then row = {}; cached_nodes[y] = row end

  local node = row[x]

  if not node then node = { x = x, y = y }; row[x] = node end

  return node

end

local neighbors_offset = {

  { -1, -1 }, { 0, -1 }, { 1, -1 },

  { -1, 0 }, { 1, 0 },

  { -1, 1 }, { 0, 1 }, { 1, 1 },

}

-- Return all neighbor nodes. Means a target that can be moved from the current node

-- add_neighbor_cb: function(new_node, cost)

--    cost is optional, call map:get_cost to get cost if no cost value

function map:get_neighbors(node, from_node, add_neighbor_cb, userdata)

  for i, offset in ipairs(neighbors_offset) do

    add_neighbor_cb(get_node(node.x + offset[1], node.y + offset[2]))

  end

end

-- Cost of two adjacent nodes.

-- Distance, distance + cost or other comparison value you want

function map:get_cost(from_node, to_node, userdata)

  return math.sqrt(math.pow(from_node.x - to_node.x, 2) + math.pow(from_node.y - to_node.y, 2))

end

-- For heuristic. Estimate cost of current node to goal node

-- As close to the real cost as possible

function map:estimate_cost(node, goal_node, userdata)

  return self:get_cost(node, goal_node)

end

local finder = AStar.new(map)

local start, goal = get_node(1, 1), get_node(3, 4)

local userdata = { 'mydata' }

local path = finder:find(start, goal, userdata)

if path then

  for _, node in ipairs(path) do

    print(node.x, node.y)

  end

else

  print("Not found path")

end

```

And you can try to run the `main.lua` by Love2d

## Better path

[This](https://www.gamasutra.com/view/feature/131505/toward_more_realistic_pathfinding.php?print=1) article tells us how to generate a smooth path with a turning radius.