The following functions must be overridden when you derive a custom class from AcDbEntity:
virtual Adesk::Boolean subWorldDraw( AcGiWorldDraw* mode); virtual Acad::ErrorStatus subGetGeomExtents( AcDbExtents& extents) const; virtual Acad::ErrorStatus subTransformBy( const AcGeMatrix3d& xform); virtual Acad::ErrorStatus subGetTransformedCopy( const AcGeMatrix3d& xform, AcDbEntity*& ent) const; virtual Acad::ErrorStatus subGetGripPoints( AcGePoint3dArray& gripPoints, AcDbIntArray& osnapModes, AcDbIntArray& geomIds) const; virtual Acad::ErrorStatus subMoveGripPointsAt( const AcDbIntArray& indices, const AcGeVector3d& offset);