AJ Isaacs
df18b72881
Add ToLine() to SplitLine and create SplitLineIntersect static class with FindIntersection, CrossesSplitLine, and SideOf methods for testing entity intersections against split lines. These helpers support the upcoming Clipper2-free DrawingSplitter rewrite. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
82 lines
2.5 KiB
C#
82 lines
2.5 KiB
C#
using OpenNest.Geometry;
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using OpenNest.Math;
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using System.Collections.Generic;
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namespace OpenNest;
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/// <summary>
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/// Static helpers for testing entity-splitline intersections.
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/// </summary>
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public static class SplitLineIntersect
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{
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/// <summary>
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/// Finds the intersection point between an entity and a split line.
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/// Returns null if no intersection or the entity doesn't straddle the split line.
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/// </summary>
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public static Vector? FindIntersection(Entity entity, SplitLine sl)
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{
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if (!CrossesSplitLine(entity, sl))
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return null;
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var bbox = entity.BoundingBox;
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var margin = 1.0;
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// Create a line at the split position spanning the entity's bbox extent (with margin)
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Line splitLine;
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if (sl.Axis == CutOffAxis.Vertical)
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splitLine = sl.ToLine(bbox.Bottom - margin, bbox.Top + margin);
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else
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splitLine = sl.ToLine(bbox.Left - margin, bbox.Right + margin);
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switch (entity.Type)
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{
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case EntityType.Line:
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var line = (Line)entity;
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if (Intersect.Intersects(line, splitLine, out var pt))
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return pt;
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return null;
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case EntityType.Arc:
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var arc = (Arc)entity;
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if (Intersect.Intersects(arc, splitLine, out var pts))
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return pts.Count > 0 ? pts[0] : null;
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return null;
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default:
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return null;
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}
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}
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/// <summary>
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/// Returns true if the entity's bounding box straddles the split line,
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/// meaning it extends to both sides of the split position (not just touching).
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/// </summary>
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public static bool CrossesSplitLine(Entity entity, SplitLine sl)
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{
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var bbox = entity.BoundingBox;
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if (sl.Axis == CutOffAxis.Vertical)
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return bbox.Left < sl.Position - Tolerance.Epsilon
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&& bbox.Right > sl.Position + Tolerance.Epsilon;
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else
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return bbox.Bottom < sl.Position - Tolerance.Epsilon
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&& bbox.Top > sl.Position + Tolerance.Epsilon;
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}
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/// <summary>
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/// Returns -1 if the point is below/left of the split line,
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/// +1 if above/right, or 0 if on the line (within tolerance).
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/// </summary>
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public static int SideOf(Vector pt, SplitLine sl)
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{
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var value = sl.Axis == CutOffAxis.Vertical ? pt.X : pt.Y;
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var diff = value - sl.Position;
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if (System.Math.Abs(diff) <= Tolerance.Epsilon)
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return 0;
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return diff < 0 ? -1 : 1;
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}
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}
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