116 lines
3.2 KiB
C#
116 lines
3.2 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.Linq;
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namespace OpenRA.Primitives
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{
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public readonly struct Polygon
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{
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public static readonly Polygon Empty = new Polygon(Rectangle.Empty);
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public readonly Rectangle BoundingRect;
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public readonly int2[] Vertices;
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readonly bool isRectangle;
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public Polygon(Rectangle bounds)
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{
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BoundingRect = bounds;
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Vertices = new[] { bounds.TopLeft, bounds.BottomLeft, bounds.BottomRight, bounds.TopRight };
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isRectangle = true;
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}
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public Polygon(int2[] vertices)
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{
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if (vertices != null && vertices.Length > 0)
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{
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Vertices = vertices;
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var left = int.MaxValue;
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var right = int.MinValue;
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var top = int.MaxValue;
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var bottom = int.MinValue;
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foreach (var p in vertices)
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{
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left = Math.Min(left, p.X);
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right = Math.Max(right, p.X);
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top = Math.Min(top, p.Y);
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bottom = Math.Max(bottom, p.Y);
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}
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BoundingRect = Rectangle.FromLTRB(left, top, right, bottom);
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isRectangle = false;
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}
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else
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{
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isRectangle = true;
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BoundingRect = Rectangle.Empty;
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Vertices = Exts.MakeArray(4, _ => int2.Zero);
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}
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}
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public bool IsEmpty => BoundingRect.IsEmpty;
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public bool Contains(int2 xy)
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{
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return isRectangle ? BoundingRect.Contains(xy) : Vertices.PolygonContains(xy);
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}
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public bool IntersectsWith(Rectangle rect)
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{
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var intersectsBoundingRect = BoundingRect.Left < rect.Right && BoundingRect.Right > rect.Left && BoundingRect.Top < rect.Bottom && BoundingRect.Bottom > rect.Top;
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if (isRectangle)
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return intersectsBoundingRect;
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// Easy case 1: Rect and bounding box don't intersect
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if (!intersectsBoundingRect)
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return false;
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// Easy case 2: Rect and bounding box intersect in a cross shape
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if ((rect.Left <= BoundingRect.Left && rect.Right >= BoundingRect.Right) || (rect.Top <= BoundingRect.Top && rect.Bottom >= BoundingRect.Bottom))
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return true;
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// Easy case 3: Corner of rect is inside the polygon
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if (Vertices.PolygonContains(rect.TopLeft) || Vertices.PolygonContains(rect.TopRight) || Vertices.PolygonContains(rect.BottomLeft) || Vertices.PolygonContains(rect.BottomRight))
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return true;
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// Easy case 4: Polygon vertex is inside rect
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if (Vertices.Any(p => rect.Contains(p)))
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return true;
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// Hard case: check intersection of every line segment pair
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var rectVertices = new[]
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{
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rect.TopLeft,
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rect.BottomLeft,
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rect.BottomRight,
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rect.TopRight
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};
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for (var i = 0; i < Vertices.Length; i++)
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for (var j = 0; j < 4; j++)
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if (Exts.LinesIntersect(Vertices[i], Vertices[(i + 1) % Vertices.Length], rectVertices[j], rectVertices[(j + 1) % 4]))
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return true;
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return false;
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}
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public override int GetHashCode()
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{
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var code = BoundingRect.GetHashCode();
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foreach (var v in Vertices)
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code = ((code << 5) + code) ^ v.GetHashCode();
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return code;
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}
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}
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}
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