Today, I compiled Water tank project code and trying to open .g format file in FreeCAD by converting .g format file to other format but unable to open it.
Other files include brep-files for objects and thumbnail of drawing. BesidesFreeCAD’s own file format, files could be exchanged by the following file formats: DXF, SVG (Scalable Vector Graphics), STEP, IGES, STL (STereoLithography), OBJ (Wavefront), DAE (Collada), SCAD (OpenSCAD), IV (Inventor) and IFC. (https://en.wikipedia.org/wiki/FreeCAD)
Output of Water tank project after compilation: