ECCOMPARE — Visually compare 2 DWGs

Visually compare two versions of a DWG drawing directly in AutoCAD. Colour-coded overlay: green = elements of the current version, red = elements of the old version, magenta = identical elements. PDF export of the comparison.

How it works

  1. Launch ECCOMPARE and select the reference DWG (previous version)
  2. ElectroCAD clones the entities of the old version into your current drawing via WblockCloneObjects
  3. The XRefs of the old version are resolved and bound to guarantee the display
  4. A primitive-based matching identifies common entities (with recursive block explosion and O(n) spatial hashing)
  5. The colored overlay applies: green/red/magenta depending on the status of each entity
  6. A WPF panel lets you toggle visibility by colour and adjust the matching tolerance

Smart primitive-based matching

ECCOMPARE does not use a simple coordinate diff — exploded blocks would look different even if they represent the same thing. Instead:

  • Complex entities (blocks, inserts) are exploded recursively into primitives (lines, arcs, circles, texts)
  • Each primitive is hashed by its spatial position, its type and its geometric parameters
  • Matching is performed in O(n) via spatial hash, with configurable tolerance
  • Unmatched entities are marked as added (green) or deleted (red)

WPF control panel

A modeless WPF panel is displayed as an overlay on AutoCAD and allows:

  • Visibility toggle: show/hide added (green), deleted (red), unchanged (magenta)
  • Tolerance slider with on-the-fly matching recalculation
  • "Export PDF" button to export the comparison
  • "Finish" button that restores the original drawing (command ECCOMPAREOFF)

Use cases

  • Change review — compare two versions of a drawing for a client or a coordinator
  • Project audit — quickly identify the changes between two milestones
  • Pre-delivery check — make sure a delivered drawing matches the latest approved version
  • Conflict resolution — when two drafters have modified the same file
  • Comparing an XRef before/after update

Commands

Command: ECCOMPARE # Start the comparison Command: ECCOMPAREOFF # Restore the original drawing Command: ECCOMPAREEXPORT # PDF export (temporary A3 layout + legend)

ECCOMPARE is included in ElectroCAD Tools

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