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use dictionaries in favor of lists for AStar to speed up pathfinding

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Ell 2020-09-10 02:12:53 +02:00
parent a5c1b6c2b4
commit 4f63770de0
1 changed files with 18 additions and 20 deletions
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38
MLEM/Pathfinding/AStar.cs
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@ -1,6 +1,7 @@
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading.Tasks;
namespace MLEM.Pathfinding {
@ -91,25 +92,23 @@ namespace MLEM.Pathfinding {
var tries = maxTries ?? this.DefaultMaxTries;
var defCost = defaultCost ?? this.DefaultCost;
var open = new List<PathPoint<T>>();
var closed = new List<PathPoint<T>>();
open.Add(new PathPoint<T>(start, this.GetManhattanDistance(start, goal), null, 0, defCost));
var open = new Dictionary<T, PathPoint<T>>();
var closed = new Dictionary<T, PathPoint<T>>();
open.Add(start, new PathPoint<T>(start, this.GetManhattanDistance(start, goal), null, 0, defCost));
var count = 0;
Stack<T> ret = null;
while (open.Count > 0) {
PathPoint<T> current = null;
var lowestF = float.MaxValue;
foreach (var point in open)
if (point.F < lowestF) {
foreach (var point in open.Values) {
if (current == null || point.F < current.F)
current = point;
lowestF = point.F;
}
}
if (current == null)
break;
open.Remove(current);
closed.Add(current);
open.Remove(current.Pos);
closed.Add(current.Pos, current);
if (current.Pos.Equals(goal)) {
ret = CompilePath(current);
@ -120,20 +119,19 @@ namespace MLEM.Pathfinding {
foreach (var dir in dirsUsed) {
var neighborPos = this.AddPositions(current.Pos, dir);
var cost = getCost(current.Pos, neighborPos);
if (!float.IsInfinity(cost) && cost < float.MaxValue) {
if (!float.IsInfinity(cost) && cost < float.MaxValue && !closed.ContainsKey(neighborPos)) {
var neighbor = new PathPoint<T>(neighborPos, this.GetManhattanDistance(neighborPos, goal), current, cost, defCost);
if (!closed.Contains(neighbor)) {
var alreadyIndex = open.IndexOf(neighbor);
if (alreadyIndex < 0) {
open.Add(neighbor);
// check if we already have a waypoint at this location with a worse path
if (open.TryGetValue(neighborPos, out var alreadyNeighbor)) {
if (neighbor.G < alreadyNeighbor.G) {
open.Remove(neighborPos);
} else {
var alreadyNeighbor = open[alreadyIndex];
if (neighbor.G < alreadyNeighbor.G) {
open.Remove(alreadyNeighbor);
open.Add(neighbor);
}
// if the old waypoint is better, we don't add ours
continue;
}
}
// add the new neighbor as a possible waypoint
open.Add(neighborPos, neighbor);
}
}