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some more AStar improvements

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Ell 2022-10-09 21:04:39 +02:00
parent 3e4c4e566d
commit 0b6e6743cf
3 changed files with 89 additions and 9 deletions
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3
CHANGELOG.md
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@ -20,8 +20,9 @@ Improvements
- Improved EnumHelper.GetValues signature to return an array
- Allow using external gesture handling alongside InputHandler through ExternalGestureHandling
- Discard old data when updating a StaticSpriteBatch
- **Drastically improved StaticSpriteBatch batching performance**
- Multi-target net452, making MLEM compatible with MonoGame for consoles
- Allow retrieving the cost of a calculated path when using AStar
- **Drastically improved StaticSpriteBatch batching performance**
Fixes
- Fixed TokenizedString handling trailing spaces incorrectly in the last line of non-left aligned text

63
MLEM/Pathfinding/AStar.cs
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@ -78,7 +78,7 @@ namespace MLEM.Pathfinding {
this.DefaultSpecialDirections = defaultSpecialDirections;
}
/// <inheritdoc cref="FindPath"/>
/// <inheritdoc cref="FindPath(T,T,MLEM.Pathfinding.AStar{T}.GetCost,System.Nullable{float},System.Nullable{int},System.Nullable{bool},MLEM.Pathfinding.AStar{T}.GetSpecialDirections)"/>
public Task<Stack<T>> FindPathAsync(T start, T goal, GetCost costFunction = null, float? defaultCost = null, int? maxTries = null, bool? allowDiagonals = null) {
return Task.Run(() => this.FindPath(start, goal, costFunction, defaultCost, maxTries, allowDiagonals));
}
@ -95,8 +95,59 @@ namespace MLEM.Pathfinding {
/// <param name="specialDirections">An optional function that determines a set of additional directions (or offsets) that should be tested for walkability.</param>
/// <returns>A stack of path points, where the top item is the first point to go to, or null if no path was found.</returns>
public Stack<T> FindPath(T start, T goal, GetCost costFunction = null, float? defaultCost = null, int? maxTries = null, bool? allowDiagonals = null, GetSpecialDirections specialDirections = null) {
var stopwatch = Stopwatch.StartNew();
this.TryFindPath(start, goal, out var path, out _, costFunction, defaultCost, maxTries, allowDiagonals, specialDirections);
return path;
}
/// <inheritdoc cref="FindPath(T,IEnumerable{T},MLEM.Pathfinding.AStar{T}.GetCost,System.Nullable{float},System.Nullable{int},System.Nullable{bool},MLEM.Pathfinding.AStar{T}.GetSpecialDirections)"/>
public Task<Stack<T>> FindPathAsync(T start, IEnumerable<T> goals, GetCost costFunction = null, float? defaultCost = null, int? maxTries = null, bool? allowDiagonals = null) {
return Task.Run(() => this.FindPath(start, goals, costFunction, defaultCost, maxTries, allowDiagonals));
}
/// <summary>
/// Tries to find paths between a <paramref name="start"/> position and a set of <paramref name="goals"/> and returns the path that had the lowest overall cost.
/// Note that this method is only faster than a one-to-many pathfinding method like Dijkstra's algorithm in situations where the amount of possible <paramref name="goals"/> is much lower than the total amount of possible positions, or the <paramref name="goals"/> are relatively close to each other.
/// </summary>
/// <param name="start">The point to start path finding at</param>
/// <param name="goals">The set of points to try to find a path to</param>
/// <param name="costFunction">The function that determines the cost for each path point</param>
/// <param name="defaultCost">The default cost for each path point</param>
/// <param name="maxTries">The maximum amount of tries before path finding is aborted</param>
/// <param name="allowDiagonals">If diagonals should be looked at for path finding</param>
/// <param name="specialDirections">An optional function that determines a set of additional directions (or offsets) that should be tested for walkability.</param>
/// <returns>A stack of path points, where the top item is the first point to go to, or null if no paths were found.</returns>
public Stack<T> FindPath(T start, IEnumerable<T> goals, GetCost costFunction = null, float? defaultCost = null, int? maxTries = null, bool? allowDiagonals = null, GetSpecialDirections specialDirections = null) {
var lowestCost = float.PositiveInfinity;
Stack<T> cheapestPath = null;
foreach (var goal in goals) {
if (!this.TryFindPath(start, goal, out var path, out var cost, costFunction, defaultCost, maxTries, allowDiagonals, specialDirections))
continue;
if (cost < lowestCost) {
lowestCost = cost;
cheapestPath = path;
}
}
return cheapestPath;
}
/// <summary>
/// Tries to find a path between two points using this pathfinder's default settings or, alternatively, the supplied override settings.
/// </summary>
/// <param name="start">The point to start path finding at</param>
/// <param name="goal">The point to find a path to</param>
/// <param name="path">The path that was found, or <see langword="null"/> if no path was found.</param>
/// <param name="totalCost">The total cost that was calculated for the path, or <see cref="float.PositiveInfinity"/> if no path was found.</param>
/// <param name="costFunction">The function that determines the cost for each path point</param>
/// <param name="defaultCost">The default cost for each path point</param>
/// <param name="maxTries">The maximum amount of tries before path finding is aborted</param>
/// <param name="allowDiagonals">If diagonals should be looked at for path finding</param>
/// <param name="specialDirections">An optional function that determines a set of additional directions (or offsets) that should be tested for walkability.</param>
/// <returns>Whether a path was found.</returns>
public bool TryFindPath(T start, T goal, out Stack<T> path, out float totalCost, GetCost costFunction = null, float? defaultCost = null, int? maxTries = null, bool? allowDiagonals = null, GetSpecialDirections specialDirections = null) {
path = null;
totalCost = float.PositiveInfinity;
var stopwatch = Stopwatch.StartNew();
var getCost = costFunction ?? this.DefaultCostFunction;
var diags = allowDiagonals ?? this.DefaultAllowDiagonals;
var tries = maxTries ?? this.DefaultMaxTries;
@ -108,7 +159,6 @@ namespace MLEM.Pathfinding {
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;
foreach (var point in open.Values) {
@ -122,7 +172,8 @@ namespace MLEM.Pathfinding {
closed.Add(current.Pos, current);
if (current.Pos.Equals(goal)) {
ret = AStar<T>.CompilePath(current);
path = AStar<T>.CompilePath(current);
totalCost = current.F;
break;
}
@ -141,7 +192,7 @@ namespace MLEM.Pathfinding {
stopwatch.Stop();
this.LastTriesNeeded = count;
this.LastTimeNeeded = stopwatch.Elapsed;
return ret;
return path != null;
void ExamineDirection(PathPoint<T> current, T dir) {
var neighborPos = this.AddPositions(current.Pos, dir);
@ -192,7 +243,7 @@ namespace MLEM.Pathfinding {
public delegate float GetCost(T currPos, T nextPos);
/// <summary>
/// A delegate used by <see cref="AStar{T}.DefaultSpecialDirections"/> and <see cref="AStar{T}.FindPath"/> that determines a set of additional directions (or offsets) that should be tested for walkability.
/// A delegate used by <see cref="AStar{T}.DefaultSpecialDirections"/> and <see cref="AStar{T}.TryFindPath"/> that determines a set of additional directions (or offsets) that should be tested for walkability.
/// </summary>
/// <param name="currPos">The current position in the path.</param>
/// <returns>A set of additional directions (or offsets) that should be checked for walkability. If the given <paramref name="currPos"/> has no special directions, an empty <see cref="IEnumerable{T}"/> should be returned.</returns>

32
Tests/PathfindingTests.cs
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@ -80,14 +80,42 @@ namespace Tests {
p => p.X == 2 && p.Y == 2 ? new[] {new Point(-1, 2)} : Enumerable.Empty<Point>()));
}
[Test]
public void TestMultiplePaths() {
var area = new[] {
"XXXXXXXX",
"X 2 X",
"XXXXX X",
"X 53 X",
"X XXX X",
"X X X X",
"XXXXXXXX"
};
var pathfinder = PathfindingTests.CreatePathfinder(area, false);
var goals = new[] {new Point(1, 5), new Point(3, 5), new Point(5, 5)};
var goalCosts = new[] {19, float.PositiveInfinity, 9};
for (var i = 0; i < goals.Length; i++) {
pathfinder.TryFindPath(new Point(1, 1), goals[i], out _, out var cost);
Assert.AreEqual(goalCosts[i], cost);
}
var path = pathfinder.FindPath(new Point(1, 1), goals).ToArray();
var expected = new[] {new Point(1, 1), new Point(2, 1), new Point(3, 1), new Point(4, 1), new Point(5, 1), new Point(5, 2), new Point(5, 3), new Point(5, 4), new Point(5, 5)};
Assert.AreEqual(path, expected);
}
private static Stack<Point> FindPathInArea(Point start, Point end, IEnumerable<string> area, bool allowDiagonals, AStar2.GetSpecialDirections getSpecialDirections = null) {
return PathfindingTests.CreatePathfinder(area, allowDiagonals, getSpecialDirections).FindPath(start, end);
}
private static AStar2 CreatePathfinder(IEnumerable<string> area, bool allowDiagonals, AStar2.GetSpecialDirections getSpecialDirections = null) {
var costs = area.Select(s => s.Select(c => c switch {
' ' => 1,
'X' => float.PositiveInfinity,
_ => (float) char.GetNumericValue(c)
}).ToArray()).ToArray();
var pathFinder = new AStar2((_, p2) => costs[p2.Y][p2.X], allowDiagonals, 1, 64, getSpecialDirections);
return pathFinder.FindPath(start, end);
return new AStar2((_, p2) => costs[p2.Y][p2.X], allowDiagonals, 1, 64, getSpecialDirections);
}
}