2016-12-11 19:24:52 +00:00
|
|
|
-- Astar algorithm
|
|
|
|
-- This actual implementation of A-star is based on
|
|
|
|
-- [Nash A. & al. pseudocode](http://aigamedev.com/open/tutorials/theta-star-any-angle-paths/)
|
|
|
|
|
|
|
|
if (...) then
|
|
|
|
|
|
|
|
-- Internalization
|
|
|
|
local huge = math.huge
|
|
|
|
|
|
|
|
-- Dependancies
|
|
|
|
local _PATH = (...):match('(.+)%.search.astar$')
|
|
|
|
local Heap = require (_PATH.. '.core.bheap')
|
|
|
|
|
|
|
|
-- Updates G-cost
|
2017-10-26 22:56:55 +00:00
|
|
|
local function computeCost(node, neighbour, heuristic)
|
2016-12-11 19:24:52 +00:00
|
|
|
local mCost, heading = heuristic(neighbour, node) -- Heuristics.EUCLIDIAN(neighbour, node)
|
|
|
|
|
|
|
|
if node._g + mCost < neighbour._g then
|
|
|
|
neighbour._parent = node
|
|
|
|
neighbour._g = node._g + mCost
|
|
|
|
neighbour._heading = heading
|
|
|
|
end
|
|
|
|
end
|
|
|
|
|
|
|
|
-- Updates vertex node-neighbour
|
2017-10-26 22:56:55 +00:00
|
|
|
local function updateVertex(openList, node, neighbour, endNode, heuristic)
|
2016-12-11 19:24:52 +00:00
|
|
|
local oldG = neighbour._g
|
2017-10-26 22:56:55 +00:00
|
|
|
computeCost(node, neighbour, heuristic)
|
2016-12-11 19:24:52 +00:00
|
|
|
if neighbour._g < oldG then
|
2017-10-26 22:56:55 +00:00
|
|
|
if neighbour._opened then neighbour._opened = false end
|
|
|
|
neighbour._h = heuristic(endNode, neighbour)
|
|
|
|
neighbour._f = neighbour._g + neighbour._h
|
|
|
|
openList:push(neighbour)
|
|
|
|
neighbour._opened = true
|
2016-12-11 19:24:52 +00:00
|
|
|
end
|
|
|
|
end
|
|
|
|
|
|
|
|
-- Calculates a path.
|
|
|
|
-- Returns the path from location `<startX, startY>` to location `<endX, endY>`.
|
2017-10-26 22:56:55 +00:00
|
|
|
return function (finder, startNode, endNode, toClear)
|
2016-12-11 19:24:52 +00:00
|
|
|
local openList = Heap()
|
|
|
|
startNode._g = 0
|
2017-10-26 22:56:55 +00:00
|
|
|
startNode._h = finder._heuristic(endNode, startNode)
|
2016-12-11 19:24:52 +00:00
|
|
|
startNode._f = startNode._g + startNode._h
|
|
|
|
openList:push(startNode)
|
|
|
|
toClear[startNode] = true
|
|
|
|
startNode._opened = true
|
|
|
|
|
|
|
|
while not openList:empty() do
|
|
|
|
local node = openList:pop()
|
|
|
|
node._closed = true
|
|
|
|
if node == endNode then return node end
|
2017-10-26 22:56:55 +00:00
|
|
|
local neighbours = finder._grid:getNeighbours(node)
|
2016-12-11 19:24:52 +00:00
|
|
|
for i = 1,#neighbours do
|
|
|
|
local neighbour = neighbours[i]
|
|
|
|
if not neighbour._closed then
|
|
|
|
toClear[neighbour] = true
|
|
|
|
if not neighbour._opened then
|
|
|
|
neighbour._g = huge
|
2017-10-26 22:56:55 +00:00
|
|
|
neighbour._parent = nil
|
2016-12-11 19:24:52 +00:00
|
|
|
end
|
2017-10-26 22:56:55 +00:00
|
|
|
updateVertex(openList, node, neighbour, endNode, finder._heuristic)
|
|
|
|
end
|
2016-12-11 19:24:52 +00:00
|
|
|
end
|
|
|
|
|
|
|
|
--[[
|
|
|
|
printf('x:%d y:%d z:%d g:%d', node._x, node._y, node._z, node._g)
|
|
|
|
for i = 1,#neighbours do
|
|
|
|
local n = neighbours[i]
|
|
|
|
printf('x:%d y:%d z:%d f:%f g:%f h:%d', n._x, n._y, n._z, n._f, n._g, n._heading or -1)
|
|
|
|
end
|
|
|
|
--]]
|
|
|
|
|
|
|
|
end
|
2017-10-26 22:56:55 +00:00
|
|
|
return nil
|
2016-12-11 19:24:52 +00:00
|
|
|
end
|
|
|
|
end
|