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feat: improve BLF with Clipper paths, spatial pruning, and progress

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Refactor BLF to compute NFP paths as Clipper PathsD with offsets
instead of translating full polygons. Add spatial pruning to skip
NFPs that don't intersect the IFP bounds. Clamp placement points
to IFP bounds to correct Clipper2 floating-point drift. Add
progress reporting to simulated annealing. Add debug logging.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
AJ Isaacs
2026-03-20 14:43:04 -04:00
parent 9411dd0fdd
commit d9d275b675
2 changed files with 91 additions and 66 deletions
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111
OpenNest.Engine/Nfp/BottomLeftFill.cs
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@@ -1,5 +1,8 @@
using OpenNest.Geometry;
using System;
using System.Collections.Generic;
using System.IO;
using Clipper2Lib;
namespace OpenNest.Engine.Nfp
{
@@ -10,6 +13,9 @@ namespace OpenNest.Engine.Nfp
/// </summary>
public class BottomLeftFill
{
private static readonly string DebugLogPath = Path.Combine(
Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "nest-debug.log");
private readonly Box workArea;
private readonly NfpCache nfpCache;
@@ -21,55 +27,56 @@ namespace OpenNest.Engine.Nfp
/// <summary>
/// Places parts according to the given sequence using NFP-based BLF.
/// Each entry is (drawingId, rotation) determining what to place and how.
/// Returns the list of successfully placed parts with their positions.
/// </summary>
public List<PlacedPart> Fill(List<(int drawingId, double rotation, Drawing drawing)> sequence)
public List<PlacedPart> Fill(List<SequenceEntry> sequence)
{
var placedParts = new List<PlacedPart>();
foreach (var (drawingId, rotation, drawing) in sequence)
using var log = new StreamWriter(DebugLogPath, false);
log.WriteLine($"[BLF] {DateTime.Now:HH:mm:ss.fff} workArea: X={workArea.X} Y={workArea.Y} W={workArea.Width} H={workArea.Length} Right={workArea.Right} Top={workArea.Top}");
log.WriteLine($"[BLF] Sequence count: {sequence.Count}");
foreach (var entry in sequence)
{
var polygon = nfpCache.GetPolygon(drawingId, rotation);
if (polygon == null || polygon.Vertices.Count < 3)
continue;
// Compute IFP for this part inside the work area.
var ifp = InnerFitPolygon.Compute(workArea, polygon);
var ifp = nfpCache.GetIfp(entry.DrawingId, entry.Rotation, workArea);
if (ifp.Vertices.Count < 3)
continue;
// Compute NFPs against all already-placed parts.
var nfps = new Polygon[placedParts.Count];
for (var i = 0; i < placedParts.Count; i++)
{
var placed = placedParts[i];
var nfp = nfpCache.Get(placed.DrawingId, placed.Rotation, drawingId, rotation);
// Translate NFP to the placed part's position.
var translated = TranslatePolygon(nfp, placed.Position);
nfps[i] = translated;
log.WriteLine($"[BLF] DrawingId={entry.DrawingId} rot={entry.Rotation:F3} SKIPPED (IFP has {ifp.Vertices.Count} verts)");
continue;
}
// Compute feasible region and find bottom-left point.
var feasible = InnerFitPolygon.ComputeFeasibleRegion(ifp, nfps);
log.WriteLine($"[BLF] DrawingId={entry.DrawingId} rot={entry.Rotation:F3} IFP verts={ifp.Vertices.Count} bounds=({ifp.BoundingBox.X:F2},{ifp.BoundingBox.Y:F2},{ifp.BoundingBox.Width:F2},{ifp.BoundingBox.Length:F2})");
var nfpPaths = ComputeNfpPaths(placedParts, entry.DrawingId, entry.Rotation, ifp.BoundingBox);
var feasible = InnerFitPolygon.ComputeFeasibleRegion(ifp, nfpPaths);
var point = InnerFitPolygon.FindBottomLeftPoint(feasible);
if (double.IsNaN(point.X))
{
log.WriteLine($"[BLF] -> NO feasible point (NaN)");
continue;
}
// Clamp to IFP bounds to correct Clipper2 floating-point drift.
var ifpBb = ifp.BoundingBox;
point = new Vector(
System.Math.Max(ifpBb.X, System.Math.Min(ifpBb.Right, point.X)),
System.Math.Max(ifpBb.Y, System.Math.Min(ifpBb.Top, point.Y)));
log.WriteLine($"[BLF] -> placed at ({point.X:F4}, {point.Y:F4}) nfpPaths={nfpPaths.Count} feasibleVerts={feasible.Vertices.Count}");
placedParts.Add(new PlacedPart
{
DrawingId = drawingId,
Rotation = rotation,
DrawingId = entry.DrawingId,
Rotation = entry.Rotation,
Position = point,
Drawing = drawing
Drawing = entry.Drawing
});
}
log.WriteLine($"[BLF] Total placed: {placedParts.Count}/{sequence.Count}");
return placedParts;
}
@@ -82,12 +89,12 @@ namespace OpenNest.Engine.Nfp
foreach (var placed in placedParts)
{
var part = new Part(placed.Drawing);
if (placed.Rotation != 0)
part.Rotate(placed.Rotation);
part.Location = placed.Position;
var part = Part.CreateAtOrigin(placed.Drawing, placed.Rotation);
// CreateAtOrigin sets Location to compensate for the rotated program's
// bounding box offset. The BLF position is a displacement for the
// origin-normalized polygon, so we ADD it to the existing Location
// rather than replacing it.
part.Location = part.Location + placed.Position;
parts.Add(part);
}
@@ -95,27 +102,31 @@ namespace OpenNest.Engine.Nfp
}
/// <summary>
/// Creates a translated copy of a polygon.
/// Computes NFPs for a candidate part against all already-placed parts,
/// returned as Clipper paths with translations applied.
/// Filters NFPs that don't intersect the target IFP.
/// </summary>
private static Polygon TranslatePolygon(Polygon polygon, Vector offset)
private PathsD ComputeNfpPaths(List<PlacedPart> placedParts, int drawingId, double rotation, Box ifpBounds)
{
var result = new Polygon();
var nfpPaths = new PathsD(placedParts.Count);
foreach (var v in polygon.Vertices)
result.Vertices.Add(new Vector(v.X + offset.X, v.Y + offset.Y));
for (var i = 0; i < placedParts.Count; i++)
{
var placed = placedParts[i];
var nfp = nfpCache.Get(placed.DrawingId, placed.Rotation, drawingId, rotation);
return result;
if (nfp != null && nfp.Vertices.Count >= 3)
{
// Spatial pruning: only include NFPs that could actually subtract from the IFP.
var nfpBounds = nfp.BoundingBox.Translate(placed.Position);
if (nfpBounds.Intersects(ifpBounds))
{
nfpPaths.Add(NoFitPolygon.ToClipperPath(nfp, placed.Position));
}
}
}
return nfpPaths;
}
}
/// <summary>
/// Represents a part that has been placed by the BLF algorithm.
/// </summary>
public class PlacedPart
{
public int DrawingId { get; set; }
public double Rotation { get; set; }
public Vector Position { get; set; }
public Drawing Drawing { get; set; }
}
}