Hello,
I used CADSys4 because:
I developed the module for LazCAD (which also uses the CADSys4 library). and
I use the DXF interface of CADSys4 in the module.
The author (Piero Valagussa) has generously contributed over 20,000 lines of 2D and 3D Pascal source code (Delphi/Lazarus/FPC) to the Pascal community—completely for free. The library seamlessly adapts: in Delphi, it remains Delphi-native; in FPC, it is FPC-native. :-)
Best regards,
Maurog.