ARC2SEG-bgol (Arc/Circle to Segmented Polyline)

Command Type: AutoLISP routine (works in AutoCAD, BricsCAD, ZWCAD and most AutoLISP-compatible CAD platforms)
Developed by: BGol Community, bgol.in

Inspired by the general concept of arc-to-polyline conversion utilities used in CAD/survey drafting. This is an original, independently written routine, new file name, new command name, new source code, created so the CAD community has a free, editable, open-source alternative.

Overview

A2S converts a selected ARC or CIRCLE entity into an equivalent LWPOLYLINE made of many short straight-line segments that closely approximate the original curve. Many downstream tools and export formats don't handle true arc geometry well, this routine solves that at the source.

How to Use

1. Load ARC2SEG-bgol.lsp into your CAD session (drag-and-drop the file onto the drawing window, or use the APPLOAD command).
2. Type A2S at the command line and press Enter.
3. Select the ARC or CIRCLE entity you want to convert.
4. A new segmented LWPOLYLINE is created on a dedicated layer, BGOL-A2S (colour cyan), closely tracing the original curve.
5. The original arc/circle is left untouched, so you can compare or delete it manually.

Why Use It

• Compatibility, converts curved geometry into a straight-segment format that other LISP routines and export formats handle reliably.
• Export reliability, avoids failures or data loss when sending drawings containing arcs to software that doesn't process curves well.
• Prerequisite step, many vertex-based tools (vertex export, insertion, marking, etc.) expect straight-segment polylines; this routine prepares arc-containing geometry for that kind of processing.

Where to Use It

• Preparing drawings with arcs or circles for export to arc-incompatible software.
• Converting arcs to line segments before running other vertex-based tools that require straight-segment polylines.
• Any workflow needing curved geometry approximated with straight segments for measurement, processing, or compatibility reasons.

Notes

• Segmentation resolution defaults to roughly 5-degree steps (a minimum of 8 segments for short arcs, 72 segments for a full circle). Edit the *bgol-a2s-step* constant near the top of the .lsp file to change resolution.
• Works on ARC and CIRCLE entities; other entity types are reported and skipped.
• Source code is fully open, feel free to study, modify, and redistribute it under the same open, free-for-all spirit.

Credits

Developed and shared for the CAD community by BGol Community. Website: https://bgol.in/ Free and open-source, use it, modify it, share it, for personal or commercial work alike.