AstralTransRocketries/TrueCraft
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Implement A* pathfinding and relevant tests

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This commit is contained in:
Drew DeVault 2015-07-02 17:05:44 -06:00
parent fc6f88a87b
commit f2ab1c0598
8 changed files with 228 additions and 2 deletions
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10
TrueCraft.API/PathResult.cs Normal file
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using System;
using System.Collections.Generic;
namespace TrueCraft.API
{
public class PathResult
{
public IList<Coordinates3D> Waypoints;
}
}

1
TrueCraft.API/TrueCraft.API.csproj
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@ -109,6 +109,7 @@
<Compile Include="ToolType.cs" />
<Compile Include="World\ChunkLoadedEventArgs.cs" />
<Compile Include="IEventSubject.cs" />
<Compile Include="PathResult.cs" />
</ItemGroup>
<Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
<ItemGroup />

105
TrueCraft.Core.Test/AI/PathFindingTest.cs Normal file
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using System;
using NUnit.Framework;
using TrueCraft.Core.TerrainGen;
using TrueCraft.API;
using TrueCraft.Core.AI;
using TrueCraft.API.World;
using TrueCraft.Core.World;
using System.Linq;
namespace TrueCraft.Core.Test.AI
{
[TestFixture]
public class PathFindingTest
{
private void DrawGrid(PathResult path, IWorld world)
{
for (int z = -8; z < 8; z++)
{
for (int x = -8; x < 8; x++)
{
var coords = new Coordinates3D(x, 4, z);
if (path.Waypoints.Contains(coords))
Console.Write("o");
else
{
var id = world.GetBlockID(coords);
if (id != 0)
Console.Write("x");
else
Console.Write("_");
}
}
Console.WriteLine();
}
}
[Test]
public void TestAStarLinearPath()
{
var world = new TrueCraft.Core.World.World("default", new FlatlandGenerator());
var astar = new AStarPathFinder();
var path = astar.FindPath(world, new BoundingBox(),
new Coordinates3D(0, 4, 0), new Coordinates3D(5, 4, 0));
DrawGrid(path, world);
var expected = new[]
{
new Coordinates3D(0, 4, 0),
new Coordinates3D(1, 4, 0),
new Coordinates3D(2, 4, 0),
new Coordinates3D(3, 4, 0),
new Coordinates3D(4, 4, 0),
new Coordinates3D(5, 4, 0)
};
for (int i = 0; i < path.Waypoints.Count; i++)
Assert.AreEqual(expected[i], path.Waypoints[i]);
}
[Test]
public void TestAStarDiagonalPath()
{
var world = new TrueCraft.Core.World.World("default", new FlatlandGenerator());
var astar = new AStarPathFinder();
var start = new Coordinates3D(0, 4, 0);
var end = new Coordinates3D(5, 4, 5);
var path = astar.FindPath(world, new BoundingBox(), start, end);
DrawGrid(path, world);
// Just test the start and end, the exact results need to be eyeballed
Assert.AreEqual(start, path.Waypoints[0]);
Assert.AreEqual(end, path.Waypoints[path.Waypoints.Count - 1]);
}
[Test]
public void TestAStarObstacle()
{
var world = new TrueCraft.Core.World.World("default", new FlatlandGenerator());
var astar = new AStarPathFinder();
var start = new Coordinates3D(0, 4, 0);
var end = new Coordinates3D(5, 4, 0);
world.SetBlockID(new Coordinates3D(3, 4, 0), 1); // Obstacle
var path = astar.FindPath(world, new BoundingBox(), start, end);
DrawGrid(path, world);
// Just test the start and end, the exact results need to be eyeballed
Assert.AreEqual(start, path.Waypoints[0]);
Assert.AreEqual(end, path.Waypoints[path.Waypoints.Count - 1]);
Assert.IsFalse(path.Waypoints.Contains(new Coordinates3D(3, 4, 0)));
}
[Test]
public void TestAStarImpossible()
{
var world = new TrueCraft.Core.World.World("default", new FlatlandGenerator());
var astar = new AStarPathFinder();
var start = new Coordinates3D(0, 4, 0);
var end = new Coordinates3D(5, 4, 0);
world.SetBlockID(start + Coordinates3D.East, 1);
world.SetBlockID(start + Coordinates3D.West, 1);
world.SetBlockID(start + Coordinates3D.North, 1);
world.SetBlockID(start + Coordinates3D.South, 1);
var path = astar.FindPath(world, new BoundingBox(), start, end);
Assert.IsNull(path);
}
}
}

4
TrueCraft.Core.Test/TrueCraft.Core.Test.csproj
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@ -35,7 +35,7 @@
<HintPath>..\packages\NUnit.2.6.4\lib\nunit.framework.dll</HintPath>
</Reference>
<Reference Include="Moq">
<HintPath>..\packages\Moq.4.2.1502.0911\lib\net40\Moq.dll</HintPath>
<HintPath>..\packages\Moq.4.2.1507.0118\lib\net40\Moq.dll</HintPath>
</Reference>
</ItemGroup>
<Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
@ -83,6 +83,7 @@
<Compile Include="Windows\CraftingWindowAreaTest.cs" />
<Compile Include="Logic\BlockProviderTest.cs" />
<Compile Include="Lighting\WorldLighterTest.cs" />
<Compile Include="AI\PathFindingTest.cs" />
</ItemGroup>
<ItemGroup>
<Folder Include="World\" />
@ -90,5 +91,6 @@
<Folder Include="Windows\" />
<Folder Include="Logic\" />
<Folder Include="Lighting\" />
<Folder Include="AI\" />
</ItemGroup>
</Project>

2
TrueCraft.Core.Test/packages.config
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@ -1,5 +1,5 @@
<?xml version="1.0" encoding="utf-8"?>
<packages>
<package id="Moq" version="4.2.1502.0911" targetFramework="net45" />
<package id="Moq" version="4.2.1507.0118" targetFramework="net45" />
<package id="NUnit" version="2.6.4" targetFramework="net45" />
</packages>

68
TrueCraft.Core/AI/AStarPathFinder.cs Normal file
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using System;
using System.Collections.Generic;
using TrueCraft.API;
using TrueCraft.API.World;
namespace TrueCraft.Core.AI
{
public class AStarPathFinder
{
private readonly Coordinates3D[] Neighbors =
{
Coordinates3D.North,
Coordinates3D.East,
Coordinates3D.South,
Coordinates3D.West
};
private PathResult TracePath(Coordinates3D start, Coordinates3D goal, Dictionary<Coordinates3D, Coordinates3D> parents)
{
var list = new List<Coordinates3D>();
var current = goal;
while (current != start)
{
current = parents[current];
list.Insert(0, current);
}
list.Add(goal);
return new PathResult { Waypoints = list };
}
public PathResult FindPath(IWorld world, BoundingBox subject, Coordinates3D start, Coordinates3D goal)
{
// Thanks to www.redblobgames.com/pathfinding/a-star/implementation.html
var parents = new Dictionary<Coordinates3D, Coordinates3D>();
var costs = new Dictionary<Coordinates3D, int>();
var frontier = new PriorityQueue<Coordinates3D>();
frontier.Enqueue(start, 0);
parents[start] = start;
costs[start] = 0;
while (frontier.Count > 0)
{
var current = frontier.Dequeue();
if (current == goal)
return TracePath(start, goal, parents);
for (int i = 0; i < Neighbors.Length; i++)
{
var next = Neighbors[i] + current;
var id = world.GetBlockID(next);
if (id != 0)
continue; // TODO: Make this more sophisticated
var cost = (int)(costs[current] + current.DistanceTo(next));
if (!costs.ContainsKey(next) || cost < costs[next])
{
costs[next] = cost;
var priority = (int)(cost + next.DistanceTo(goal));
frontier.Enqueue(next, priority);
parents[next] = current;
}
}
}
return null;
}
}
}

37
TrueCraft.Core/AI/PriorityQueue.cs Normal file
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using System;
using System.Collections.Generic;
namespace TrueCraft.Core.AI
{
// TODO: Replace this with something better eventually
// Thanks to www.redblobgames.com/pathfinding/a-star/implementation.html
public class PriorityQueue<T>
{
private List<Tuple<T, int>> elements = new List<Tuple<T, int>>();
public int Count
{
get { return elements.Count; }
}
public void Enqueue(T item, int priority)
{
elements.Add(Tuple.Create(item, priority));
}
public T Dequeue()
{
int bestIndex = 0;
for (int i = 0; i < elements.Count; i++) {
if (elements[i].Item2 < elements[bestIndex].Item2) {
bestIndex = i;
}
}
T bestItem = elements[bestIndex].Item1;
elements.RemoveAt(bestIndex);
return bestItem;
}
}
}

3
TrueCraft.Core/TrueCraft.Core.csproj
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@ -328,6 +328,8 @@
<Compile Include="TerrainGen\EmptyGenerator.cs" />
<Compile Include="Logic\ItemRepository.cs" />
<Compile Include="Lighting\WorldLighting.cs" />
<Compile Include="AI\AStarPathFinder.cs" />
<Compile Include="AI\PriorityQueue.cs" />
</ItemGroup>
<Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
<ItemGroup>
@ -352,6 +354,7 @@
</ProjectExtensions>
<ItemGroup>
<Folder Include="Lighting\" />
<Folder Include="AI\" />
</ItemGroup>
<ItemGroup>
<None Include="packages.config" />