[Free LISP] Auto-mark revision clouds for design changes — compare two regions in same DWG

[Beastt1992]

Every design revision, I have to circle changes with revision clouds for submission. 
I kept missing things or marking the wrong spots, so I wrote a LISP to do it automatically.

What it does:
1. Select Region A (old version)
2. Select Region B (revised version)  
3. Red revision clouds appear around every difference

It works inside the same DWG — no need for two separate files like DWG Compare. 
Uses signature-based object comparison with sorted merge, so it handles 1400+ objects in seconds.

Features:
- Automatic spatial alignment (consensus voting)
- Nearby changes merged into grouped clouds
- Giant objects (title blocks, borders) auto-filtered
- Manual 2-point alignment fallback if auto fails
- Configurable tolerance, arc size, merge distance

Supports: LINE, CIRCLE, ARC, LWPOLYLINE, TEXT/MTEXT, INSERT, DIMENSION
Skips: HATCH (too many false positives)

AutoCAD 2014+ compatible. 

Free / MIT: https://github.com/beastt1992/DiffCheck

Feedback welcome

Edited 4 hours ago by Beastt1992
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