FillLinear re-prepared offset perimeter geometry (ConvertProgram -> ShapeProfile -> OffsetOutward) for every part it measured, although tiled copies share one Program and differ only by Location. A CPU profile of a 169-part Default job put 62% of wall time there. Prepare each distinct Program (reference identity) once per public Fill/FillRow call in local frame, then clone and translate for each location. The cache is created per call and passed down privately because FillHelpers.FillPattern calls Fill concurrently on one instance. PartGeometry gains a local-frame Program overload that the Part overload now delegates to. Evaluation order, lazy preparation, fallbacks and tiling are unchanged. Differential tests against a frozen copy of the previous FillLinear check bitwise equality, including concurrent calls; Debug work tests pin preparation counts. With the thread pool capped at one worker, before/after whole-job layouts are byte-identical. The Default corpus job median drops from 40,715 to 18,810 ms.
OpenNest
A Windows desktop application for CNC nesting — imports DXF drawings, arranges parts on material plates, and exports layouts as DXF or G-code for cutting.
Features
- Import / export — DXF & DWG parts (ACadSharp), Excel BOMs, bend-line detection, built-in parametric shapes; export DXF or post-processed G-code.
- Nesting — pluggable whole-job engines (Default, Strip, Vertical/Horizontal Remnant, StockLadder, plus DLL plugins), NFP-based interlocking pair evaluation, gravity compaction, rotation sweeps, multi-plate/multi-material jobs.
- Plate operations — sheet cut-offs, oversized-part splitting (straight, weld-gap tabs, spike-groove), interactive editing.
- CNC output — configurable lead-ins/outs and tabs, contour editing, user-defined G-code variables (
$name→#200+machine variables), plugin post-processors (Cincinnati CL-707/800/900/940/CLX included).
Requirements
- Windows 10+ for the desktop app; the console, API, and most test projects build on Linux/macOS too.
- .NET 8 SDK
Build, Test, Run
git clone https://git.thecozycat.net/aj/OpenNest.git
cd OpenNest
dotnet build OpenNest.sln # full solution (Windows)
dotnet test OpenNest.Engine.Tests/OpenNest.Engine.Tests.csproj # cross-platform engine tests
dotnet test OpenNest.Tests/OpenNest.Tests.csproj # core/engine/IO/API tests
dotnet run --project OpenNest/OpenNest.csproj # desktop app (Windows)
OpenNest.WinForms.Tests (desktop-assembly tests) runs on Windows only. Format changed files with dotnet format OpenNest.sln --include <path>.
Shared coding-agent guidance lives in AGENTS.md. CLAUDE.md imports it for Claude Code compatibility; make shared instruction changes in AGENTS.md, not in duplicate agent-specific copies.
Quick start
- File > New Nest
- Import DXFs via the CAD Converter (layer/color filtering, bend detection, G-code preview) or create built-in shapes
- Define plate size, material, quadrant, spacing
- Fill — the engine arranges parts
- Optionally add cut-off lines, then save
.nest, export DXF, or post-process to G-code
Command-Line Interface
dotnet run --project OpenNest.Console -- part.dxf --size 60x120 # fill one plate
dotnet run --project OpenNest.Console -- part1.dxf part2.dxf --size 60x120 --autonest
dotnet run --project OpenNest.Console -- project.zip # re-fill a nest file
Key options: --size WxL, --autonest (whole-job nesting), --engine <name> (jobs engine or fill strategy), --quantity, --spacing, --template <nest>, --output <path>, --check-overlaps, --post <name>, --no-save. Run without arguments for the full list.
Benchmarking Engines
OpenNest.Benchmark runs every registered INestingEngine against .nest files (or a JSON manifest of DXFs + quantities) and scores by salvage-credited sheet area, with a penalty per unplaced part.
dotnet run --project OpenNest.Benchmark -- ./benchmark-jobs \
--sheet-sizes 48x96,60x120,72x120 --engines Default,StockLadder --csv results.csv
Layouts are validated (bounds, spacing, quantity, rotation, stock match); invalid runs place nothing and pay the penalty. --parallel (default 3) speeds up scoring but inflates Time(ms) — use --parallel 1 when comparing speed. Pass --sheet-sizes for an unbiased run; otherwise only each file's original sizes are offered. --progress logs each solve's start, the engine's NestJobProgress (plate evaluations throttled to one line per 2 s, every plate commit) and its finish. Custom engines drop in as DLLs implementing INestingEngine (public parameterless constructor) in an Engines/ folder next to the benchmark. Community engines live in OpenNest-Engines.
Project Structure
| Project | Purpose |
|---|---|
| OpenNest | WinForms desktop app |
| OpenNest.Core | Domain model, geometry, CNC primitives |
| OpenNest.Engine | Nesting algorithms and whole-job contracts |
| OpenNest.IO | DXF/DWG, .nest, G-code, BOM I/O; CAD import |
| OpenNest.Console | Headless batch nesting |
| OpenNest.Api / .Data | Programmatic pipeline; machine & cutting-parameter data |
| OpenNest.Gpu | GPU-accelerated pair evaluation (ILGPU) |
| OpenNest.Benchmark | Head-to-head engine comparison |
| OpenNest.Mcp | MCP server for AI tool integration |
| OpenNest.Posts.Cincinnati | Cincinnati laser post-processor plugin |
| *.Tests | Cross-platform suites; WinForms tests are Windows-only |
Nesting Engines
Jobs-only API: engines implement INestingEngine.Solve(NestJob); only NestJobRunner commits demand and stock, and every candidate passes the placement validator (bounds, spacing, rotation policy, stock match) before it consumes anything.
| Engine | Description |
|---|---|
| Default | Multi-phase: linear fill → pairs → rect best-fit → extents |
| Strip | Iterative shrink-fill for mixed-drawing layouts |
| Vertical / Horizontal Remnant | Optimizes a clean remnant drop on one edge |
| StockLadder | Whole-job, stock-constrained baseline with salvage-credit ranking |
File Format
.nest files are ZIP archives: nest.json (metadata, plates, drawings, placements), programs/program-N (G-code per drawing), optional entities/, sub-programs, and cached best-fit data.
Supported Formats
| Format | Import | Export |
|---|---|---|
| DXF | Yes | Yes |
| DWG | Yes | No |
| Excel BOM | Yes | No |
| G-code | No | Yes (post-processors) |
.nest |
Yes | Yes |
Keyboard Shortcuts
Ctrl+F fill area · F zoom to fit · Shift+wheel / middle-click rotate · X/Y push · arrows nudge · Shift+arrow push.
Status & License
Actively developed; core workflows run end-to-end from DXF import to G-code. Contributions welcome. MIT licensed — see LICENSE.

