BTW, I want to let Arch objects, Sketch etc. to show a legend / hint about the ‘Origin’ / X-Y-Z direction similar to that as shown in the screen-capture. Anyone has idea how to implement ? Thanks 
Another idea: Is anyone familiar with the way that dimensions can be used in Revit to locate objects? Could draft dimensions be made to work this way? I am not able to confirm this at the moment, but I think the FC sketcher already kind of works like this. From the Sketcher documentation:
“Objects do not need to be drawn exactly as you intend to, because they will be defined later on by constraints”.
In Revit one activates the object and the dimensions associated with the object becomes editable, then the user can edit the dimension and the object will move accordingly.
Edit: In Revit I usually get objects close first, and then place them accurately by this dimension method, or by using construction lines.
Not familiar with Revit, somehow Sketcher works similarly though; maybe you can setup a simple workflow with diagram to illustrate your idea ?
Here are some screenshots of me manipulating a door location via this method. Hopefully these show okay, and in the correct order.
- Place a door
- I add a dimension from the inner corner of the wall to the edge of the door opening (2’-2 1/4")
- Click on the door. You will see that it is highlighted purple. Revit automatically creates some other light blue dimensions that can be used the same way, but ignore those for the sake of this discussion. The dimension that I added manually becomes editable (blue field)
- I change the dimension to 4’ and the door moves accordingly.
This has got me to thinking more since my last post. What if every element in the BIM environment had some “footprint” element (like a wall trace) that maps out on a sketcher plane that exists on the plane of the level so that items could be manipulated in this kind of way? I’m not sure exactly how it could work. It seems like a cumbersome process to activate the sketcher move something, then close it every time we want to move something, but maybe something like it could always be active in the background? of the BIM environment? I really don’t know how FreeCAD works under the hood, so I am just throwing ideas out.
EDIT: I just played around with the sketcher in FreeCAD, and it does work somewhat similarly–for example with with a rectangle:
- Draw a rectangle
- Add a “Constrain Block” constraint to the left vertical line
- Add a “Constrain Horizontal Distance” dimension to the top or bottom horizontal line.
- Edit the horizontal distance constraint, and the right vertical line will move to that distance from the left line.