49 lines
1.5 KiB
C#
49 lines
1.5 KiB
C#
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using System;
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using System.Collections.Generic;
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using System.Diagnostics;
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using Microsoft.Msagl.Core.Geometry;
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using Microsoft.Msagl.Core;
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namespace Microsoft.Msagl.Routing.Visibility {
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internal class ObstacleSideComparer : IComparer<SegmentBase> {
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readonly LineSweeperBase lineSweeper;
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internal ObstacleSideComparer(LineSweeperBase lineSweeper) {
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this.lineSweeper = lineSweeper;
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}
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/// <summary>
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/// the intersection of the sweepline and the active segment
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/// </summary>
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Point x;
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public int Compare(SegmentBase a, SegmentBase b) {
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ValidateArg.IsNotNull(b, "b");
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var orient = Point.GetTriangleOrientation(b.Start, b.End, x);
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switch (orient) {
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case TriangleOrientation.Collinear:
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return 0;
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case TriangleOrientation.Clockwise:
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return 1;
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default:
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return -1;
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}
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}
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internal void SetOperand(SegmentBase side) {
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x = IntersectionOfSideAndSweepLine(side);
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}
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internal Point IntersectionOfSideAndSweepLine(SegmentBase obstacleSide) {
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var den = obstacleSide.Direction * lineSweeper.SweepDirection;
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Debug.Assert(Math.Abs(den) > ApproximateComparer.DistanceEpsilon);
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var t = (lineSweeper.Z - obstacleSide.Start * lineSweeper.SweepDirection) / den;
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return obstacleSide.Start + t * obstacleSide.Direction;
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}
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}
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}
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