mirror of
https://github.com/kepler155c/opus
synced 2024-11-15 21:24:49 +00:00
98 lines
3.6 KiB
Lua
98 lines
3.6 KiB
Lua
--- Heuristic functions for search algorithms.
|
|
-- A <a href="http://theory.stanford.edu/~amitp/GameProgramming/Heuristics.html">distance heuristic</a>
|
|
-- provides an *estimate of the optimal distance cost* from a given location to a target.
|
|
-- As such, it guides the pathfinder to the goal, helping it to decide which route is the best.
|
|
--
|
|
-- This script holds the definition of some built-in heuristics available through jumper.
|
|
--
|
|
-- Distance functions are internally used by the `pathfinder` to evaluate the optimal path
|
|
-- from the start location to the goal. These functions share the same prototype:
|
|
-- local function myHeuristic(nodeA, nodeB)
|
|
-- -- function body
|
|
-- end
|
|
-- Jumper features some built-in distance heuristics, namely `MANHATTAN`, `EUCLIDIAN`, `DIAGONAL`, `CARDINTCARD`.
|
|
-- You can also supply your own heuristic function, following the same template as above.
|
|
|
|
|
|
local abs = math.abs
|
|
local sqrt = math.sqrt
|
|
local sqrt2 = sqrt(2)
|
|
local max, min = math.max, math.min
|
|
|
|
local Heuristics = {}
|
|
--- Manhattan distance.
|
|
-- <br/>This heuristic is the default one being used by the `pathfinder` object.
|
|
-- <br/>Evaluates as <code>distance = |dx|+|dy|</code>
|
|
-- @class function
|
|
-- @tparam node nodeA a node
|
|
-- @tparam node nodeB another node
|
|
-- @treturn number the distance from __nodeA__ to __nodeB__
|
|
-- @usage
|
|
-- -- First method
|
|
-- pathfinder:setHeuristic('MANHATTAN')
|
|
-- -- Second method
|
|
-- local Distance = require ('jumper.core.heuristics')
|
|
-- pathfinder:setHeuristic(Distance.MANHATTAN)
|
|
function Heuristics.MANHATTAN(nodeA, nodeB)
|
|
local dx = abs(nodeA._x - nodeB._x)
|
|
local dy = abs(nodeA._y - nodeB._y)
|
|
local dz = abs(nodeA._z - nodeB._z)
|
|
return (dx + dy + dz)
|
|
end
|
|
|
|
--- Euclidian distance.
|
|
-- <br/>Evaluates as <code>distance = squareRoot(dx*dx+dy*dy)</code>
|
|
-- @class function
|
|
-- @tparam node nodeA a node
|
|
-- @tparam node nodeB another node
|
|
-- @treturn number the distance from __nodeA__ to __nodeB__
|
|
-- @usage
|
|
-- -- First method
|
|
-- pathfinder:setHeuristic('EUCLIDIAN')
|
|
-- -- Second method
|
|
-- local Distance = require ('jumper.core.heuristics')
|
|
-- pathfinder:setHeuristic(Distance.EUCLIDIAN)
|
|
function Heuristics.EUCLIDIAN(nodeA, nodeB)
|
|
local dx = nodeA._x - nodeB._x
|
|
local dy = nodeA._y - nodeB._y
|
|
local dz = nodeA._z - nodeB._z
|
|
return sqrt(dx*dx+dy*dy+dz*dz)
|
|
end
|
|
|
|
--- Diagonal distance.
|
|
-- <br/>Evaluates as <code>distance = max(|dx|, abs|dy|)</code>
|
|
-- @class function
|
|
-- @tparam node nodeA a node
|
|
-- @tparam node nodeB another node
|
|
-- @treturn number the distance from __nodeA__ to __nodeB__
|
|
-- @usage
|
|
-- -- First method
|
|
-- pathfinder:setHeuristic('DIAGONAL')
|
|
-- -- Second method
|
|
-- local Distance = require ('jumper.core.heuristics')
|
|
-- pathfinder:setHeuristic(Distance.DIAGONAL)
|
|
function Heuristics.DIAGONAL(nodeA, nodeB)
|
|
local dx = abs(nodeA._x - nodeB._x)
|
|
local dy = abs(nodeA._y - nodeB._y)
|
|
return max(dx,dy)
|
|
end
|
|
|
|
--- Cardinal/Intercardinal distance.
|
|
-- <br/>Evaluates as <code>distance = min(dx, dy)*squareRoot(2) + max(dx, dy) - min(dx, dy)</code>
|
|
-- @class function
|
|
-- @tparam node nodeA a node
|
|
-- @tparam node nodeB another node
|
|
-- @treturn number the distance from __nodeA__ to __nodeB__
|
|
-- @usage
|
|
-- -- First method
|
|
-- pathfinder:setHeuristic('CARDINTCARD')
|
|
-- -- Second method
|
|
-- local Distance = require ('jumper.core.heuristics')
|
|
-- pathfinder:setHeuristic(Distance.CARDINTCARD)
|
|
function Heuristics.CARDINTCARD(nodeA, nodeB)
|
|
local dx = abs(nodeA._x - nodeB._x)
|
|
local dy = abs(nodeA._y - nodeB._y)
|
|
return min(dx,dy) * sqrt2 + max(dx,dy) - min(dx,dy)
|
|
end
|
|
|
|
return Heuristics |