AutoCAD® and Proxy Objects
Comments by: Odin Cary

Welcome to a new era of translation issues in the world of CAD. When I was just beginning with AutoCAD in 1985, getting lines and arcs out of AutoCAD® into another program was a major feat. DXF (drawing exchange format), created by Autodesk, was our only option - if memory serves me right. As the years went by, the translation issue became less of a problem with respect to the basic native objects, but the inherent data associated with those objects often had problems. Until just recently, most of my clients were fairly happy if the CAD vectors would just translate cleanly; a door remained a door and so on. And today many other CAD programs can actually read and write AutoCAD files directly ( Allplan and IntelliCAD, for example ).

What's this stuff about
But now we have a new object in the world of AutoCAD and it has come along as a result of our growing need for more "intelligence" in our CAD systems. Autodesk is not the only company developing "smart" objects, so this translation issue is not an isolated problem. The new AutoCAD objects are based on the AutoCAD Runtime Extension (ARX): basically, the ability to run more sophisticated, compiled and object oriented programming (C++) inside of AutoCAD ( a wall is more than two parallel lines ). These new objects or Arx Objects cannot function as "intelligent" objects without the code that makes them "intelligent" and thus if you separate the object from what makes it intelligent, you get a Proxy Object: something that holds the shape and form of its original intent.

Am I using ARX
To see just how many Arx application you are currently running, simply type "ARX" on your AutoCAD R14 command line. You should see a reference to the Bonus utilities; that's right, you've been using "intelligence" without knowing it. But chances are, somebody has noticed your use of intelligent objects because Wipeout, for example, when translated to an AutoCAD R13 user can drive them crazy.

Turning Proxy Graphics off
To control the "Proxy-fication" (my made up word) of these new objects, you have a variable called, "PROXYGRAPHICS". This variable can be set to "0" which will remove the Proxy images when saving your files. Our tests found that ADT files actually grew in size when we turned this variable off. Another way to control the output of Proxy images, is to pick the Options button on the Save As... dialogue box: here you can chose to save with or without the Proxy images.

Translating is the creators responsibility
If you are a user of an AutoCAD® "flavor", like Architectural DesktopTM , then the problem of translation rests upon you. You will have to provide a "readable" file for anyone you're attempting to exchange work with. If you plan to circulate that work back and forth and maintain your object "intelligence", then you may face some serious problems; depending on the CAD programs you're exchanging with.

Arx Objects to AutoCAD R14
R14special flavor - > R14regular

Our tests found that AutoCAD R14 will display the new Arx Objects created by a "flavor" of AutoCAD R14 as "Proxy Objects", but provide little to no ability for editing of these special objects. Fortunately, there is a simple solution to this problem: download the "AEC Object Enabler" plug-in from Autodesk's Website or load it off of the AutoCAD R14 "flavor" installation CD. For more on the "AEC Object Enabler" look in our ADT Tips and Tricks Directory.

Arx Objects to older versions of AutoCAD
R14 - > R13
Our tests found that if you save your AutoCAD Arx Objects to an AutoCAD R13 format, the original object "intelligence" remains; even on the return route - from the R13 user to R14. However, the R13 user will not be able to work with the resultant "Zombie" objects which may thus make this feature useless. When we saved the R14 Arx Objects to R13 format with the PROXYGRAPHICS variable turned off, the resultant R13 file appeared as a 2D drawing. The doors and windows were displayed as simple rectangles, they listed as "Zombie" objects and when we attempted to move them, R13 crashed.

R14 - > R12
Our tests found that if you save your AutoCAD Arx Objects to an AutoCAD R12 format, everything is basically flattened (lines, arcs and circles). Unfortunately this means that the original object "intelligence" is also lost but on the flip side, this method translates quite well; this procedure will also work for R13 users.

Arx Objects to other CAD programs
R14 - > Other CAD Programs
Our tests found numerous problems with the DXFout (drawing exchange format) process on Architectural Desktop (which is built over AutoCAD R14.01). The DXFout to an AutoCAD R12 format produced the only usable results in our tests.

For more on ADT Arx Object Translation issues, see our review on ADT.