a1a583ea0a
Move the domain logic involved into a base class named DensePathGraph. The base class contains all the domain logic necessary to traverse a graph including concepts such as custom movement layer. PathGraph becomes responsible for proving a backing array for the pathfinding information, and is where the pooling logic lives instead, helping split the two concepts out.
226 lines
8.5 KiB
C#
226 lines
8.5 KiB
C#
#region Copyright & License Information
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/*
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* Copyright 2007-2022 The OpenRA Developers (see AUTHORS)
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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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using System.Linq;
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using OpenRA.Mods.Common.Traits;
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namespace OpenRA.Mods.Common.Pathfinder
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{
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/// <summary>
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/// A dense pathfinding graph that implements the ability to cost and get connections for cells,
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/// and supports <see cref="ICustomMovementLayer"/>. Allows searching over a dense grid of cells.
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/// Derived classes are required to provide backing storage for the pathfinding information.
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/// </summary>
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abstract class DensePathGraph : IPathGraph
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{
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const int LaneBiasCost = 1;
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protected readonly ICustomMovementLayer[] CustomMovementLayers;
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readonly int customMovementLayersEnabledForLocomotor;
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readonly Locomotor locomotor;
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readonly Actor actor;
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readonly World world;
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readonly BlockedByActor check;
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readonly Func<CPos, int> customCost;
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readonly Actor ignoreActor;
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readonly bool laneBias;
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readonly bool inReverse;
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readonly bool checkTerrainHeight;
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protected DensePathGraph(Locomotor locomotor, Actor actor, World world, BlockedByActor check,
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Func<CPos, int> customCost, Actor ignoreActor, bool laneBias, bool inReverse)
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{
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CustomMovementLayers = world.GetCustomMovementLayers();
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customMovementLayersEnabledForLocomotor = CustomMovementLayers.Count(cml => cml != null && cml.EnabledForLocomotor(locomotor.Info));
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this.locomotor = locomotor;
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this.world = world;
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this.actor = actor;
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this.check = check;
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this.customCost = customCost;
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this.ignoreActor = ignoreActor;
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this.laneBias = laneBias;
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this.inReverse = inReverse;
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checkTerrainHeight = world.Map.Grid.MaximumTerrainHeight > 0;
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}
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public abstract CellInfo this[CPos node] { get; set; }
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/// <summary>
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/// Determines if a candidate neighbouring position is
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/// allowable to be returned in a <see cref="GraphConnection"/>.
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/// </summary>
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/// <param name="neighbor">The candidate cell. This might not lie within map bounds.</param>
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protected virtual bool NeighborAllowable(CPos neighbor)
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{
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return true;
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}
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// Sets of neighbors for each incoming direction. These exclude the neighbors which are guaranteed
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// to be reached more cheaply by a path through our parent cell which does not include the current cell.
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// For horizontal/vertical directions, the set is the three cells 'ahead'. For diagonal directions, the set
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// is the three cells ahead, plus the two cells to the side. Effectively, these are the cells left over
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// if you ignore the ones reachable from the parent cell.
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// We can do this because for any cell in range of both the current and parent location,
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// if we can reach it from one we are guaranteed to be able to reach it from the other.
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static readonly CVec[][] DirectedNeighbors =
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{
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new[] { new CVec(-1, -1), new CVec(0, -1), new CVec(1, -1), new CVec(-1, 0), new CVec(-1, 1) }, // TL
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new[] { new CVec(-1, -1), new CVec(0, -1), new CVec(1, -1) }, // T
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new[] { new CVec(-1, -1), new CVec(0, -1), new CVec(1, -1), new CVec(1, 0), new CVec(1, 1) }, // TR
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new[] { new CVec(-1, -1), new CVec(-1, 0), new CVec(-1, 1) }, // L
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CVec.Directions,
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new[] { new CVec(1, -1), new CVec(1, 0), new CVec(1, 1) }, // R
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new[] { new CVec(-1, -1), new CVec(-1, 0), new CVec(-1, 1), new CVec(0, 1), new CVec(1, 1) }, // BL
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new[] { new CVec(-1, 1), new CVec(0, 1), new CVec(1, 1) }, // B
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new[] { new CVec(1, -1), new CVec(1, 0), new CVec(-1, 1), new CVec(0, 1), new CVec(1, 1) }, // BR
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};
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// With height discontinuities between the parent and current cell, we cannot optimize the possible neighbors.
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// It is no longer true that for any cell in range of both the current and parent location,
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// if we can reach it from one we are guaranteed to be able to reach it from the other.
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// This is because a height discontinuity may have prevented the parent location from reaching,
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// but our current cell on a new height may be able to reach as the height difference may be small enough.
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// Therefore, we can only exclude the parent cell in each set of directions.
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static readonly CVec[][] DirectedNeighborsConservative =
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{
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CVec.Directions.Exclude(new CVec(1, 1)).ToArray(), // TL
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CVec.Directions.Exclude(new CVec(0, 1)).ToArray(), // T
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CVec.Directions.Exclude(new CVec(-1, 1)).ToArray(), // TR
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CVec.Directions.Exclude(new CVec(1, 0)).ToArray(), // L
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CVec.Directions,
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CVec.Directions.Exclude(new CVec(-1, 0)).ToArray(), // R
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CVec.Directions.Exclude(new CVec(1, -1)).ToArray(), // BL
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CVec.Directions.Exclude(new CVec(0, -1)).ToArray(), // B
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CVec.Directions.Exclude(new CVec(-1, -1)).ToArray(), // BR
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};
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public List<GraphConnection> GetConnections(CPos position)
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{
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var layer = position.Layer;
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var info = this[position];
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var previousNode = info.PreviousNode;
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var dx = position.X - previousNode.X;
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var dy = position.Y - previousNode.Y;
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var index = dy * 3 + dx + 4;
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var heightLayer = world.Map.Height;
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var directions =
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(checkTerrainHeight && layer == 0 && previousNode.Layer == 0 && heightLayer[position] != heightLayer[previousNode]
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? DirectedNeighborsConservative
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: DirectedNeighbors)[index];
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var validNeighbors = new List<GraphConnection>(directions.Length + (layer == 0 ? customMovementLayersEnabledForLocomotor : 1));
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for (var i = 0; i < directions.Length; i++)
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{
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var dir = directions[i];
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var neighbor = position + dir;
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if (!NeighborAllowable(neighbor))
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continue;
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var pathCost = GetPathCostToNode(position, neighbor, dir);
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if (pathCost != PathGraph.PathCostForInvalidPath &&
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this[neighbor].Status != CellStatus.Closed)
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validNeighbors.Add(new GraphConnection(neighbor, pathCost));
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}
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if (layer == 0)
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{
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foreach (var cml in CustomMovementLayers)
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{
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if (cml == null || !cml.EnabledForLocomotor(locomotor.Info))
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continue;
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var layerPosition = new CPos(position.X, position.Y, cml.Index);
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if (!NeighborAllowable(layerPosition))
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continue;
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var entryCost = cml.EntryMovementCost(locomotor.Info, layerPosition);
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if (entryCost != PathGraph.MovementCostForUnreachableCell &&
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CanEnterNode(position, layerPosition) &&
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this[layerPosition].Status != CellStatus.Closed)
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validNeighbors.Add(new GraphConnection(layerPosition, entryCost));
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}
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}
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else
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{
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var groundPosition = new CPos(position.X, position.Y, 0);
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if (NeighborAllowable(groundPosition))
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{
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var exitCost = CustomMovementLayers[layer].ExitMovementCost(locomotor.Info, groundPosition);
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if (exitCost != PathGraph.MovementCostForUnreachableCell &&
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CanEnterNode(position, groundPosition) &&
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this[groundPosition].Status != CellStatus.Closed)
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validNeighbors.Add(new GraphConnection(groundPosition, exitCost));
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}
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}
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return validNeighbors;
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}
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bool CanEnterNode(CPos srcNode, CPos destNode)
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{
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return
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locomotor.MovementCostToEnterCell(actor, srcNode, destNode, check, ignoreActor)
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!= PathGraph.MovementCostForUnreachableCell;
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}
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int GetPathCostToNode(CPos srcNode, CPos destNode, CVec direction)
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{
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var movementCost = locomotor.MovementCostToEnterCell(actor, srcNode, destNode, check, ignoreActor);
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if (movementCost != PathGraph.MovementCostForUnreachableCell)
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return CalculateCellPathCost(destNode, direction, movementCost);
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return PathGraph.PathCostForInvalidPath;
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}
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int CalculateCellPathCost(CPos neighborCPos, CVec direction, short movementCost)
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{
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var cellCost = direction.X * direction.Y != 0
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? Exts.MultiplyBySqrtTwo(movementCost)
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: movementCost;
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if (customCost != null)
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{
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var customCellCost = customCost(neighborCPos);
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if (customCellCost == PathGraph.PathCostForInvalidPath)
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return PathGraph.PathCostForInvalidPath;
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cellCost += customCellCost;
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}
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// Directional bonuses for smoother flow!
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if (laneBias)
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{
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var ux = neighborCPos.X + (inReverse ? 1 : 0) & 1;
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var uy = neighborCPos.Y + (inReverse ? 1 : 0) & 1;
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if ((ux == 0 && direction.Y < 0) || (ux == 1 && direction.Y > 0))
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cellCost += LaneBiasCost;
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if ((uy == 0 && direction.X < 0) || (uy == 1 && direction.X > 0))
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cellCost += LaneBiasCost;
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}
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return cellCost;
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}
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protected virtual void Dispose(bool disposing) { }
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public void Dispose()
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{
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Dispose(true);
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}
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}
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}
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