88 lines
2.1 KiB
C#
88 lines
2.1 KiB
C#
#region Copyright & License Information
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/*
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* Copyright 2007-2010 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. For more information,
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* see LICENSE.
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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.FileFormats
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{
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public static class ConnectedComponents
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{
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static readonly int2[] Neighbors
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= { new int2(-1, -1), new int2(0, -1), new int2(1, -1), new int2(-1, 0) };
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public static int[,] Extract(Map m, Func<int, int, int> f)
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{
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var result = new int[m.MapSize.X, m.MapSize.Y];
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var types = new int[m.MapSize.X, m.MapSize.Y];
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var d = new Dictionary<int, Node>();
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var n = 1;
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for( var j = m.YOffset; j < m.YOffset + m.Height; j++ )
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for (var i = m.XOffset; i < m.XOffset + m.Width; i++)
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{
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types[i, j] = f(i, j);
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var k = n;
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foreach (var a in Neighbors)
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if (types[i + a.X, j + a.Y] == types[i, j])
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k = (k == n)
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? result[i + a.X, j + a.Y]
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: Union( d, k, result[i+a.X, j+a.Y] );
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result[i,j] = k;
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if (k == n) MakeSet(d, n++);
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}
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for (var j = m.YOffset; j < m.YOffset + m.Height; j++)
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for (var i = m.XOffset; i < m.XOffset + m.Width; i++)
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result[i, j] = Find(d, result[i, j]);
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return result;
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}
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// disjoint-set forest stuff
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class Node { public int a, b; public Node(int a, int b) { this.a = a; this.b = b; } }
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static int MakeSet(Dictionary<int, Node> d, int x)
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{
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d[x] = new Node(x, 0);
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return x;
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}
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static int Union(Dictionary<int, Node> d, int x, int y)
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{
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var xr = Find(d, x);
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var yr = Find(d, y);
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var xa = d[xr].b;
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var ya = d[yr].b;
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if (xa > ya) d[yr].a = xr;
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else if (xa < ya) d[xr].a = yr;
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else if (xr != yr)
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{
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d[yr].a = xr;
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++d[xr].b;
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}
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return xr;
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}
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static int Find(Dictionary<int, Node> d, int x)
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{
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if (d[x].a == x) return x;
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return d[x].a = Find(d, d[x].a);
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}
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}
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}
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