78 lines
2.2 KiB
C#
78 lines
2.2 KiB
C#
using System;
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namespace StructureHelperCommon.Models.Shapes
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{
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public class PolygonCalculator : IPolygonCalculator
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{
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public double GetPerimeter(IPolygonShape polygon)
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{
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if (polygon.Vertices.Count < 2)
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return 0;
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double perimeter = 0;
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for (int i = 0; i < polygon.Vertices.Count - 1; i++)
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{
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perimeter += Distance(polygon.Vertices[i].Point, polygon.Vertices[i + 1].Point);
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}
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if (polygon.IsClosed && polygon.Vertices.Count > 2)
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{
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perimeter += Distance(polygon.Vertices[^1].Point, polygon.Vertices[0].Point);
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}
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return perimeter;
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}
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public double GetArea(IPolygonShape polygon)
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{
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if (!polygon.IsClosed || polygon.Vertices.Count < 3)
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return 0;
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// Shoelace formula
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double sum = 0;
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for (int i = 0; i < polygon.Vertices.Count; i++)
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{
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var p1 = polygon.Vertices[i].Point;
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var p2 = polygon.Vertices[(i + 1) % polygon.Vertices.Count].Point;
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sum += (p1.X * p2.Y - p2.X * p1.Y);
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}
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return Math.Abs(sum) / 2.0;
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}
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public bool ContainsPoint(IPolygonShape polygon, IPoint2D point)
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{
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if (!polygon.IsClosed || polygon.Vertices.Count < 3)
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return false;
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// Ray casting algorithm
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bool inside = false;
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int j = polygon.Vertices.Count - 1;
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for (int i = 0; i < polygon.Vertices.Count; i++)
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{
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var pi = polygon.Vertices[i].Point;
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var pj = polygon.Vertices[j].Point;
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if (((pi.Y > point.Y) != (pj.Y > point.Y)) &&
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(point.X < (pj.X - pi.X) * (point.Y - pi.Y) / (pj.Y - pi.Y) + pi.X))
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{
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inside = !inside;
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}
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j = i;
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}
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return inside;
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}
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private double Distance(IPoint2D p1, IPoint2D p2)
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{
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double dx = p2.X - p1.X;
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double dy = p2.Y - p1.Y;
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return Math.Sqrt(dx * dx + dy * dy);
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}
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}
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}
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