mirror of https://github.com/kepler155c/opus
100 lines
3.5 KiB
Lua
100 lines
3.5 KiB
Lua
--- The Node class.
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-- The `node` represents a cell (or a tile) on a collision map. Basically, for each single cell (tile)
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-- in the collision map passed-in upon initialization, a `node` object will be generated
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-- and then cached within the `grid`.
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--
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-- In the following implementation, nodes can be compared using the `<` operator. The comparison is
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-- made with regards of their `f` cost. From a given node being examined, the `pathfinder` will expand the search
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-- to the next neighbouring node having the lowest `f` cost. See `core.bheap` for more details.
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--
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if (...) then
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local assert = assert
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--- The `Node` class.<br/>
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-- This class is callable.
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-- Therefore,_ <code>Node(...)</code> _acts as a shortcut to_ <code>Node:new(...)</code>.
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-- @type Node
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local Node = {}
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Node.__index = Node
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--- Inits a new `node`
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-- @class function
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-- @tparam int x the x-coordinate of the node on the collision map
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-- @tparam int y the y-coordinate of the node on the collision map
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-- @treturn node a new `node`
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-- @usage local node = Node(3,4)
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function Node:new(x,y,z)
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return setmetatable({_x = x, _y = y, _z = z, _clearance = {}}, Node)
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end
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-- Enables the use of operator '<' to compare nodes.
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-- Will be used to sort a collection of nodes in a binary heap on the basis of their F-cost
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function Node.__lt(A,B) return (A._f < B._f) end
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--- Returns x-coordinate of a `node`
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-- @class function
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-- @treturn number the x-coordinate of the `node`
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-- @usage local x = node:getX()
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function Node:getX() return self._x end
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--- Returns y-coordinate of a `node`
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-- @class function
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-- @treturn number the y-coordinate of the `node`
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-- @usage local y = node:getY()
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function Node:getY() return self._y end
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function Node:getZ() return self._z end
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--- Returns x and y coordinates of a `node`
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-- @class function
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-- @treturn number the x-coordinate of the `node`
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-- @treturn number the y-coordinate of the `node`
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-- @usage local x, y = node:getPos()
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function Node:getPos() return self._x, self._y, self._z end
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--- Returns the amount of true [clearance](http://aigamedev.com/open/tutorial/clearance-based-pathfinding/#TheTrueClearanceMetric)
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-- for a given `node`
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-- @class function
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-- @tparam string|int|func walkable the value for walkable locations in the collision map array.
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-- @treturn int the clearance of the `node`
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-- @usage
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-- -- Assuming walkable was 0
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-- local clearance = node:getClearance(0)
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function Node:getClearance(walkable)
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return self._clearance[walkable]
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end
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--- Removes the clearance value for a given walkable.
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-- @class function
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-- @tparam string|int|func walkable the value for walkable locations in the collision map array.
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-- @treturn node self (the calling `node` itself, can be chained)
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-- @usage
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-- -- Assuming walkable is defined
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-- node:removeClearance(walkable)
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function Node:removeClearance(walkable)
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self._clearance[walkable] = nil
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return self
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end
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--- Clears temporary cached attributes of a `node`.
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-- Deletes the attributes cached within a given node after a pathfinding call.
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-- This function is internally used by the search algorithms, so you should not use it explicitely.
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-- @class function
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-- @treturn node self (the calling `node` itself, can be chained)
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-- @usage
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-- local thisNode = Node(1,2)
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-- thisNode:reset()
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function Node:reset()
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self._g, self._h, self._f = nil, nil, nil
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self._opened, self._closed, self._parent = nil, nil, nil
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return self
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end
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return setmetatable(Node,
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{__call = function(self,...)
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return Node:new(...)
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end}
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)
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end |