CWWIND-bgol (Recreate Polygon Clockwise)

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 polygon-winding normalization utilities used in survey/GIS 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

CWW rebuilds a closed polygon so its vertices run clockwise, starting from a point you specify. Many survey and GIS systems require boundary polygons wound in a specific direction; a polygon drawn or imported with the opposite winding can fail validation or produce incorrect area-sign results downstream. CWW determines the current winding, reverses it if necessary, and rotates the vertex order to start exactly where you want.

How to Use

1. Load CWWIND-bgol.lsp into your CAD session (drag-and-drop the file onto the drawing window, or use the APPLOAD command).
2. Type CWW at the command line and press Enter.
3. Select a closed polyline (the routine requires the Closed property to already be set, it will abort with a message otherwise).
4. Specify a starting point; the nearest existing vertex to that point becomes the new starting vertex.
5. The routine erases the original polyline and creates a new one, starting from that vertex, with all vertices traversed clockwise, on a dedicated layer, BGOL-CWW (colour blue).

Why Use It

• Ensures compliance with survey/GIS system requirements that mandate clockwise-wound polygons, avoiding validation failures or sign- convention errors downstream.
• Gives explicit control over both the winding direction and the starting vertex, useful when a specific starting point (e.g., a legal boundary's point of commencement) is required by convention.
• Removes the need to manually determine a polygon's current winding direction and manually reverse/rebuild it by hand.

Where to Use It

• Preparing land parcel boundaries or survey polygons for export to systems that require a specific (clockwise) winding convention.
• Standardizing polygon direction across a drawing or dataset where mixed winding directions would cause inconsistent area sign results or GIS import issues.
• Any survey/cadastral workflow needing to enforce a specific starting point and winding direction on boundary polygons.

Notes

• Winding direction is computed with the shoelace (signed area) formula; the routine automatically reverses the vertex order when needed so the result is always clockwise, regardless of how the original was drawn.
• The original entity is deleted and replaced, if you need to keep the original for comparison, copy it first.
• 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.