For Nerds Only. Field Room Tags in AutoCAD.

In spite of today's powerful CAD and BIM systems, most drafting work is pretty basic. Still, AutoCAD and similar products rely on series of connected line and arc segments, usually separated by layers: CAD documents are still just drawings – mostly they do not imply any building data or structure. Definitely it's a pain if you have to populate CAD plans with space and room tags. For each change a drafter (or an architect) has to redraw the polylines and correct the attribute values of the room tags. I was looking for an AutoCAD script that simplifies the procedure of using the ‘field' feature of AutoCAD and link each room tag attribute to an area polylines. The advantage: if you change the polyline the value of the room tag changes immediately. Not quite BIM but maybe a help.

Start Visual Basic in AutoCAD. Type 'vbaide'. Paste the code and execute it. In the example you need one closed polyline and a two attributes in your room tag block. (1. room, 2. area) Please refer to the AutoCAD help if you like to integrate the tool to the user interface.

' AREA TAG TOOL
' fills an attribute with a field
' by anarchitecture

Sub fillField()
Dim mySelectionBlock As AcadObject
Dim mySelectionPoly As AcadObject
Dim myPointBlock As Variant
Dim myPointPoly As Variant
Dim tAtts As Variant
Dim varAttributes As Variant
Utility.GetEntity mySelectionBlock, myPointBlock, "Choose a Room Tag:"
varAttributes = mySelectionBlock.GetAttributes
Utility.GetEntity mySelectionPoly, myPointPoly, "Choose Polyline to be linked:"
' replace the 2nd attribute value by field value
' IMPORTANT: the tag [0.0001] converts in this example the metric drawing unit [cm] to [m]
' IMPORTANT: the value varAttributes(1).TextString replaces the 2nd attribute value in this case
varAttributes(1).TextString = "%<\AcObjProp.16.2 Object(%<\_ObjId " _ & mySelectionPoly.ObjectID & ">%).Area \f ""%lu2%pr2%ct8[0.0001]"">%"
ThisDrawing.Regen acAllViewports
End Sub