AJ Isaacs
57c35450dd
Documents both issues found (narrow pair selection, incomplete pattern tiling) and their fixes with before/after results. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
87 lines
4.4 KiB
Markdown
87 lines
4.4 KiB
Markdown
# Remnant Fill Optimization — Investigation & Fix
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## Status: Both fixes done
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## Problem 1 (FIXED): N0308-008 hinge plate remnant
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`NestEngine.Fill(NestItem, Box)` got 7 parts in a 4.7x35.0 remnant strip where manual nesting gets 8 using a staggered brick pattern with alternating rotations.
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### Test Case
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```
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load_nest("C:/Users/AJ/Desktop/N0308-008.zip")
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fill_remnants(0, "Converto 3 YRD DUMPERSTER HINGE PLATE #2") → was 7, now 9
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```
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Reference: `C:/Users/AJ/Desktop/N0308-008 - Copy.zip` (83 parts total, 8 in remnant).
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### Root Cause Found
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- FillLinear rotation sweep works correctly — tested at 1° resolution, max is always 7
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- The reference uses a **staggered pair pattern** (alternating 90°/270° rotations with horizontal offset)
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- `FillWithPairs` generates ~2572 pair candidates but only tried top 50 sorted by minimum bounding area
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- The winning pair ranked ~882nd — excluded by the `Take(50)` cutoff
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- Top-50-by-area favors compact pairs for full-plate tiling, not narrow pairs suited for remnant strips
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### Fix Applied (in `OpenNest.Engine/NestEngine.cs`)
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Added `SelectPairCandidates()` method:
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1. Always includes standard top 50 pairs by area (no change for full-plate fills)
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2. When work area is narrow (`shortSide < plateShortSide * 0.5`), includes **all** pairs whose shortest side fits the strip width
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3. Updated `FillWithPairs()` to call `SelectPairCandidates()` instead of `Take(50)`
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### Results
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- Remnant fill: 7 → **9 parts** (beats reference of 8, with partial pattern fill)
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- Full-plate fill: 75 parts (unchanged, no regression)
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- Remnant fill time: ~440ms
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- Overlap check: PASS
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---
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## Problem 2 (FIXED): N0308-017 PT02 remnant
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`N0308-017.zip` — 54 parts on a 144x72 plate. Two remnant areas:
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- Remnant 0: `(119.57, 0.75) 24.13x70.95` — end-of-sheet strip
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- Remnant 1: `(0.30, 66.15) 143.40x5.55` — bottom strip
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Drawing "4980 A24 PT02" has bbox 10.562x15.406. Engine filled 8 parts (2 cols × 4 rows) in remnant 0. Reference (`N0308-017 - Copy.zip`) has 10 parts using alternating 0°/180° rows.
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### Investigation
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1. Tested PT02 in remnant isolation → still 8 parts (not a multi-drawing ordering issue)
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2. Brute-forced all 7224 pair candidates → max was 8 (no pair yields >8 with full-pattern-only tiling)
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3. Tried finer offset resolution (0.05" step) across 0°/90°/180°/270° → still max 8
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4. Analyzed reference nest (`N0308-017 - Copy.zip`): **64 PT02 parts on full plate, 10 in remnant area**
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### Root Cause Found
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The reference uses a 0°/170° staggered pair pattern that tiles in 5 rows × 2 columns:
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- Rows at y: 0.75, 14.88, 28.40, 42.53, 56.06 (alternating 0° and 170°)
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- Pattern copy distance: ~27.65" (pair tiling distance)
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- 2 full pairs = 8 parts, top at ~58.56"
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- Remaining height: 71.70 - 58.56 = ~13.14" — enough for 1 more row of 0° parts (height 15.41)
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- **But `FillLinear.TilePattern` only placed complete pattern copies**, so the partial 3rd pair (just the 0° row) was never attempted
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The pair candidate DID exist in the candidate set and was being tried. The issue was entirely in `FillLinear.TilePattern` — it tiled 2 complete pairs (8 parts) and stopped, even though 2 more individual parts from the next incomplete pair would still fit within the work area.
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### Fix Applied (in `OpenNest.Engine/FillLinear.cs`)
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Added **partial pattern fill** to `TilePattern()`:
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- After tiling complete pattern copies, if the pattern has multiple parts, clone the next would-be copy
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- Check each individual part's bounding box against the work area
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- Add any that fit — guaranteed no overlaps by the copy distance computation
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This is safe because:
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- The copy distance ensures no overlaps between adjacent full copies → partial (subset) is also safe
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- Parts within the same pattern copy don't overlap by construction
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- Individual bounds checking catches parts that exceed the work area
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### Results
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- PT02 remnant fill: 8 → **10 parts** (matches reference)
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- Hinge remnant fill: 8 → **9 parts** (bonus improvement from same fix)
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- Full-plate fill: 75 parts (unchanged, no regression)
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- All overlap checks: PASS
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- PT02 fill time: ~32s (unchanged, dominated by pair candidate evaluation)
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---
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## Files Modified
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- `OpenNest.Engine/NestEngine.cs` — Added `SelectPairCandidates()`, updated `FillWithPairs()`, rotation sweep (pre-existing change)
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- `OpenNest.Engine/FillLinear.cs` — Added partial pattern fill to `TilePattern()`
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## Temp Files to Clean Up
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- `OpenNest.Test/` — temporary test console project (can be deleted or kept for debugging)
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