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Add Breadth-First Search pathfinder (#1283)

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Co-authored-by: Metal Gear Sloth <metalgearsloth@gmail.com>
This commit is contained in:
metalgearsloth
2020-07-08 09:41:41 +10:00
committed by GitHub
parent e7d756811e
commit 1d96adcc2c
2 changed files with 75 additions and 8 deletions
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70
Content.Server/GameObjects/EntitySystems/AI/Pathfinding/Accessible/BFSPathfinder.cs Normal file
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@@ -0,0 +1,70 @@
using System.Collections.Generic;
using Content.Server.GameObjects.EntitySystems.AI.Pathfinding.Pathfinders;
using Content.Server.GameObjects.EntitySystems.Pathfinding;
using Robust.Shared.GameObjects.Systems;
using Robust.Shared.Map;
namespace Content.Server.GameObjects.EntitySystems.AI.Pathfinding.Accessible
{
/// <summary>
/// The simplest pathfinder
/// </summary>
public sealed class BFSPathfinder
{
/// <summary>
/// Gets all of the tiles in range that can we access
/// </summary>
/// If you want Dikstra then add distances.
/// Doesn't use the JobQueue as it will generally be encapsulated by other jobs
/// <param name="pathfindingArgs"></param>
/// <param name="range"></param>
/// <param name="fromStart">Whether we traverse from the starting tile or the end tile</param>
/// <returns></returns>
public static IEnumerable<PathfindingNode> GetNodesInRange(PathfindingArgs pathfindingArgs, bool fromStart = true)
{
var pathfindingSystem = EntitySystem.Get<PathfindingSystem>();
// Don't need a priority queue given not looking for shortest path
var openTiles = new Queue<PathfindingNode>();
var closedTiles = new HashSet<TileRef>();
PathfindingNode startNode;
if (fromStart)
{
startNode = pathfindingSystem.GetNode(pathfindingArgs.Start);
}
else
{
startNode = pathfindingSystem.GetNode(pathfindingArgs.End);
}
PathfindingNode currentNode;
openTiles.Enqueue(startNode);
while (openTiles.Count > 0)
{
currentNode = openTiles.Dequeue();
foreach (var neighbor in currentNode.GetNeighbors())
{
// No distances stored so can just check closed tiles here
if (closedTiles.Contains(neighbor.TileRef)) continue;
closedTiles.Add(currentNode.TileRef);
// So currently tileCost gets the octile distance between the 2 so we'll also use that for our range check
var tileCost = PathfindingHelpers.GetTileCost(pathfindingArgs, startNode, neighbor);
var direction = PathfindingHelpers.RelativeDirection(neighbor, currentNode);
if (tileCost == null ||
tileCost > pathfindingArgs.Proximity ||
!PathfindingHelpers.DirectionTraversable(pathfindingArgs.CollisionMask, pathfindingArgs.Access, currentNode, direction))
{
continue;
}
openTiles.Enqueue(neighbor);
yield return neighbor;
}
}
}
}
}

13
Content.Server/GameObjects/EntitySystems/AI/Pathfinding/PathfindingHelpers.cs
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@@ -1,5 +1,7 @@
using System;
using System.Collections.Generic;
using Content.Server.GameObjects.Components.Access;
using Content.Server.GameObjects.EntitySystems.AI.Pathfinding.Accessible;
using Content.Server.GameObjects.EntitySystems.AI.Pathfinding.Pathfinders;
using Content.Server.GameObjects.EntitySystems.Pathfinding;
using Robust.Shared.Interfaces.GameObjects;
@@ -18,15 +20,10 @@ namespace Content.Server.GameObjects.EntitySystems.AI.Pathfinding
{
if (pathfindingArgs.Proximity > 0.0f)
{
// TODO: Should make this account for proximities,
// probably some kind of breadth-first search to find a valid one
foreach (var node in endNode.GetNeighbors())
foreach (var node in BFSPathfinder.GetNodesInRange(pathfindingArgs, false))
{
if (Traversable(pathfindingArgs.CollisionMask, pathfindingArgs.Access, node))
{
endNode = node;
return true;
}
endNode = node;
return true;
}
}