ENDCHORD-bgol (Create Polyline by Joining First and Last Point)

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 endpoint-chord simplification 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

ECHD creates a brand-new, two-point polyline by connecting only the first and last vertex of each selected polyline, discarding every intermediate vertex. It's a deliberately extreme simplification, useful when only the overall start-to-end direction of a polyline matters, not its intermediate path.

How to Use

1. Load ENDCHORD-bgol.lsp into your CAD session (drag-and-drop the file onto the drawing window, or use the APPLOAD command).
2. Type ECHD at the command line and press Enter.
3. Select one or more polylines.
4. Press Enter to finish the selection.
5. For each selected polyline, a new straight two-point polyline joining its start and end points is created on a dedicated layer, BGOL-ECHD (colour red). The original polylines are left untouched.

Why Use It

• One-step simplification, removes all unwanted intermediate vertices without manual grip-editing or PEDIT.
• Accuracy, automates the endpoint-connection process, minimizing errors from manual editing.
• Time savings, quickly reduces a noisy or over-complicated polyline down to its essential start/end geometry.

Where to Use It

• Reducing a noisy, multi-vertex polyline (e.g., a traced or auto-generated line) down to a simple straight reference line.
• Creating a quick chord line from an existing complex alignment or boundary without manually redrawing a line.
• Any cleanup task where only overall direction matters, not the intermediate path.

Notes

• This is a more extreme simplification than a tolerance-based vertex-reduction algorithm, it discards ALL intermediate vertices regardless of shape, keeping only the first and last points.
• Works on LWPOLYLINE entities; the original selected polylines are not deleted, so you can compare or remove them manually afterward.
• Polylines whose start and end point coincide (closed loops collapsed to a point) are skipped since no meaningful chord can be drawn.
• 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.