ldoc

• Index

Contents

• Functions

Modules

• gamelogic
• input
• jumper.core.bheap
• jumper.core.heuristics
• jumper.core.node
• jumper.core.path
• jumper.grid
• jumper.pathfinder
• lib.serialize
• mapgen
• output
• util

Scripts

• jumper.search.astar
• jumper.search.bfs
• jumper.search.dfs
• jumper.search.dijkstra
• jumper.search.jps

Classes

• Condition
• Creature
• Effect
• Faction
• Feature
• Item
• Map
• Projectile
• RangedAttack
• Room
• Service
• Spell
• Store

Module jumper.core.heuristics

Heuristics for the search algorithm.

A heuristic provides an *estimate of the optimal 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 built-in heuristics available.

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(dx, dy)
   -- function body
 end
 

Jumper features some built-in distance heuristics, named `MANHATTAN`, `EUCLIDIAN`, `DIAGONAL`, `CARDINTCARD`. You can also supply your own heuristic function, using the template given above.

Usage:

-- Example
local Distance = require ('jumper.core.heuristics')
local Grid = require ("jumper.grid")
local Pathfinder = require ("jumper.pathfinder")
local walkable = 0
-- Placeholder: local map = {...}
local grid = Grid(map)
local myFinder = Pathfinder('ASTAR', grid, walkable)

-- Use Euclidian heuristic to evaluate distance
myFinder:setHeuristic('EUCLIDIAN')
-- etc ...

Info:

• Copyright: 2012-2013
• License: MIT
• Author: Roland Yonaba

Functions

Heuristics.MANHATTAN (dx, dy)	Manhattan distance.
Heuristics.EUCLIDIAN (dx, dy)	Euclidian distance.
Heuristics.DIAGONAL (dx, dy)	Diagonal distance.
Heuristics.CARDINTCARD (dx, dy)	Cardinal/Intercardinal distance.

Functions

Heuristics.MANHATTAN (dx, dy)

Manhattan distance.
This heuristic is the default one being used by the `pathfinder` object.
Evaluates as `distance = |dx|+|dy|`

Parameters:

• dx int the difference endX-startX
• dy int the difference endY-startY

Returns:

number the distance from location `startX, startY` to location `endX, endY`

 -- First method
 pathfinder:setHeuristic('MANHATTAN')

 -- Second method
 local Distance = require ('jumper.core.heuristics')
 pathfinder:setHeuristic(Distance.MANHATTAN)
 

Heuristics.EUCLIDIAN (dx, dy)

Euclidian distance.
Evaluates as `distance = squareRoot(dx*dx+dy*dy)`

Parameters:

• dx int the difference endX-startX
• dy int the difference endY-startY

Returns:

number the distance from location `startX, startY` to location `endX, endY`

 -- First method
 pathfinder:setHeuristic('EUCLIDIAN')

 -- Second method
 local Distance = require ('jumper.core.heuristics')
 pathfinder:setHeuristic(Distance.EUCLIDIAN)
 

Heuristics.DIAGONAL (dx, dy)

Diagonal distance.
Evaluates as `distance = max(|dx|, abs|dy|)`

Parameters:

• dx int the difference endX-startX
• dy int the difference endY-startY

Returns:

number the distance from location `startX, startY` to location `endX, endY`

 -- First method
 pathfinder:setHeuristic('DIAGONAL')

 -- Second method
 local Distance = require ('jumper.core.heuristics')
 pathfinder:setHeuristic(Distance.DIAGONAL)
 

Heuristics.CARDINTCARD (dx, dy)

Cardinal/Intercardinal distance.
Evaluates as `distance = min(dx, dy)*squareRoot(2) + max(dx, dy) - min(dx, dy)`

Parameters:

• dx int the difference endX-startX
• dy int the difference endY-startY

Returns:

number the distance from location `startX, startY` to location `endX, endY`

 -- First method
 pathfinder:setHeuristic('CARDINTCARD')

 -- Second method
 local Distance = require ('jumper.core.heuristics')
 pathfinder:setHeuristic(Distance.CARDINTCARD)