4ec5a4b34a
The Harvester trait and MoveAdjacentTo activity called the pathfinder but had a single source and multiple targets. The pathfinder interface only allows for the opposite: multiple sources and a single target. To work around this they would swap the inputs. This works in most cases but not all cases. One aspect of asymmetry is that an actor may move out of an inaccessible source cell, but not onto an inaccessible target cell. Searches that involved an inaccessible source cell and that applied this swapping method would therefore fail to return a path, when a valid path was possible. Although a rare case, once good way to reproduce is to use a production building that spawns actors on inaccessible cells around it, such as the RA naval yard. A move order uses the pathfinder correctly and the unit will move out. Using a force attack causes the unit to use the broken "swapped" mechanism in MoveAdjacentTo and it will be stuck. This asymmetry has been longstanding but the pathfinding infrastructure only sporadically accounted for it. It is now documented and applied consistently. Create a new overload on the pathfinder trait that allows a single source and multiple targets, so callers have an overload that does what they need and won't be tempted to swap the positions and run into this issue. Internally, this requires us to teach Locomotor to ignore the self actor when performing movement cost checks for these "in reverse" searches so the unit doesn't consider the cell blocked by itself.
54 lines
1.5 KiB
C#
54 lines
1.5 KiB
C#
#region Copyright & License Information
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/*
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* Copyright (c) The OpenRA Developers and Contributors
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* This file is part of OpenRA, which is free software. It is made
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* available to you under the terms of the GNU General Public License
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* as published by the Free Software Foundation, either version 3 of
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* the License, or (at your option) any later version. For more
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* information, see COPYING.
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*/
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#endregion
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using System;
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using System.Collections.Generic;
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namespace OpenRA.Mods.Common.Pathfinder
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{
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/// <summary>
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/// A sparse pathfinding graph that supports a search over provided cells.
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/// This is a classic graph that supports an arbitrary graph of nodes and edges,
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/// and does not require a dense grid of cells.
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/// Costs and any desired connections to a <see cref="Traits.ICustomMovementLayer"/>
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/// must be provided as input.
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/// </summary>
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sealed class SparsePathGraph : IPathGraph
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{
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readonly Func<CPos, List<GraphConnection>> edges;
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readonly Dictionary<CPos, CellInfo> info;
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public SparsePathGraph(Func<CPos, List<GraphConnection>> edges, int estimatedSearchSize = 0)
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{
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this.edges = edges;
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info = new Dictionary<CPos, CellInfo>(estimatedSearchSize);
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}
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public List<GraphConnection> GetConnections(CPos position, Func<CPos, bool> targetPredicate)
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{
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return edges(position) ?? new List<GraphConnection>();
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}
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public CellInfo this[CPos pos]
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{
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get
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{
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if (info.TryGetValue(pos, out var cellInfo))
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return cellInfo;
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return default;
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}
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set => info[pos] = value;
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}
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public void Dispose() { }
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}
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}
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