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Dijkstra's algorithm using a grid for performance reasons.
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// https://gist.github.com/trystan/4968958 | |
package | |
{ | |
import flash.geom.Point; | |
public class Dijkstra | |
{ | |
private var grid:Array; | |
public function Dijkstra(w:int, h:int) | |
{ | |
grid = makeGrid(w, h); | |
} | |
private function makeGrid(w:int, h:int):Array | |
{ | |
var grid:Array = []; | |
for (var x:int = 0; x < w; x++) | |
{ | |
var row:Array = []; | |
for (var y:int = 0; y < h; y++) | |
row.push(null); | |
grid.push(row); | |
} | |
return grid; | |
} | |
private function makePath(endNode:Point):Array | |
{ | |
var path:Array = []; | |
while (grid[endNode.x][endNode.y] != endNode) | |
{ | |
path.push(endNode); | |
endNode = grid[endNode.x][endNode.y]; | |
} | |
path.push(endNode); | |
path.reverse(); | |
return path; | |
} | |
public function pathTo(start:Point, canEnter:Function, check:Function):Array | |
{ | |
var open:Array = [new Point(start.x, start.y)]; | |
grid[start.x][start.y] = open[0]; | |
while (open.length > 0) | |
{ | |
var current:Point = open[0]; | |
open.splice(0, 1); | |
if (check(current.x, current.y)) | |
return makePath(current); | |
for each (var offset:Array in [[-1,0],[0,-1],[0,1],[1,0],[-1,-1],[-1,1],[1,-1],[1,1]]) | |
{ | |
var neighbor:Point = new Point(current.x + offset[0], current.y + offset[1]); | |
if (neighbor.x < 0 | |
|| neighbor.y < 0 | |
|| neighbor.x >= grid.length | |
|| neighbor.y >= grid[0].length) | |
continue; | |
if (grid[neighbor.x][neighbor.y] != null) | |
continue; | |
grid[neighbor.x][neighbor.y] = current; | |
if (check(neighbor.x, neighbor.y)) | |
return makePath(neighbor); | |
if (!canEnter(neighbor.x, neighbor.y)) | |
continue; | |
open.push(neighbor); | |
} | |
} | |
return []; | |
} | |
public static function pathTo(start:Point, canEnter:Function, check:Function):Array | |
{ | |
return new Dijkstra(80, 60).pathTo(start, canEnter, check); | |
} | |
} | |
} |
what mean canEnter and check Functions?
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Thanks for this! Is this under any sort of open-source license?