Learn on ManuSoft

Microsoft Visual C/C++ Environment

Mon, 01 Jan 0001 00:00:00 +0000

Setting up MSVC for ObjectARX development.

Using VC Build Hook to Target Multiple AutoCAD Versions

Mon, 01 Jan 0001 00:00:00 +0000

Target multiple AutoCAD versions from one Visual Studio tree.

Demand Loading a LISP File

Mon, 01 Jan 0001 00:00:00 +0000

Demand-load a LISP or VLX file from an ObjectARX stub of the same name.

Using VC 7 to Build For AutoCAD 2000/2002

Mon, 01 Jan 0001 00:00:00 +0000

Building ObjectARX for AutoCAD 2000/2002 with Visual C++ 7.

Enabling IntelliSense and ObjectARX Class Browsing

Mon, 01 Jan 0001 00:00:00 +0000

Enable IntelliSense and browse ObjectARX classes in Visual Studio.

Using VC 7.1 to Build for AutoCAD 2000/2002/2004

Mon, 01 Jan 0001 00:00:00 +0000

Building ObjectARX for AutoCAD 2000–2004 with Visual C++ 7.1.

Bones, clones, and cyclones

Wed, 07 Nov 2018 09:22:38 +0000

My blogging has taken a nosedive in recent years, but I’m happy to report that I am doing great. I’ve been 100% focused on making sure there’s a viable alternative DWG platform for all you lost, lonely, and depressed CAD users out there. I’m going to keep this short and sweet, because as I write this I am still 100% focused on the task: putting finishing touches on BricsCAD V19 to be released “soon”.

Turning off InfoCenter in AutoCAD

Tue, 21 Mar 2017 13:47:24 +0000

Are you looking for a way to turn off the annoying InfoCenter that slows down (or sometimes locks up) your AutoCAD? Of course you are! Hop on over to the ManuSoft Freebies page and install AcadInfoCenterOff.msi, the most popular ManuSoft download of all time.

LspLoad updated for BricsCAD 17 and ZWCAD 2017

Fri, 04 Nov 2016 15:30:23 +0000

I have updated the automatic lisp loader modules (LspLoad.zip on my freebies page) to support BricsCAD V17 and ZWCAD 2017. Note that the source code for LspLoad is also available.

Service Interruptus

Tue, 07 Jul 2015 07:41:11 +0000

The ManuSoft web server has been humming along steadily for the last 7 years on an old Compaq server running Windows 2008. You may have noticed that it’s currently offline. Actually the server is still humming along just fine – it’s just that nobody can connect to it.

QuirkyPolyline updated for Bricscad and ZWCAD+

Tue, 09 Dec 2014 04:39:50 +0000

I’ve updated QuirkyPolyline and added support for Bricscad 14 – 15 and ZWCAD+ 2014 – 2015. The new QuirkyPolyline download is available on the ObjectARX freebies page.

How to fix IntelliSense errors in Visual Studio

Thu, 20 Nov 2014 22:39:40 +0000

New Visual Studio C/C++ users sometimes get tripped up by IntelliSense errors, so today I’ve decided to share the secret, undocumented solution: just turn them off!

IntelliSense is a nice user interface feature when it works, but it has nothing whatever to do with building and running your C/C++ code. IntelliSense errors do not equal compiler errors, and trying to “fix” them is fruitless.

Writing a Custom Debugger on Windows

Wed, 13 Aug 2014 05:22:38 +0000

Recently I had to debug an intermittent access violation exception in one of my AutoCAD plug-ins. I needed to get the exception while the debugger was attached so I could break the process and analyze the state of memory before AutoCAD’s global exception handler got control. Unfortunately, sometimes it took several hundred runs before the exception occurred.

AutoCAD 2015: Managing the Application Manager

Wed, 26 Mar 2014 21:49:04 +0000

AutoCAD 2015 includes a new feature called Application Manager. I’m sure it serves a lofty purpose, but it comes across a lot like the slimy Norton and Adobe updaters that are really just Trojans in disguise. It gets installed by default, with no option to prevent installation. To Autodesk’s credit, they do provide instructions for preventing installation of Application Manager, and instructions for removing it after the fact. Uninstalling requires several additional clicks, as if they really, really want you to think twice before taking such a drastic measure.

Building a commercial grade lisp plugin installer in 5 easy steps

Tue, 18 Feb 2014 01:36:34 +0000

Rumors about the death of AutoLISP have been floating around for many years, but fear not, those rumors are greatly exaggerated. Bricscad and ZWCAD both have excellent support for lisp plugins, so well-written lisp code is truly cross-platform and enjoys a large and growing audience. Unlike other languages, the vast majority of lisp code works unmodified on any hardware architecture, in any version of Windows, and inside any host application that supports it, including AutoCAD versions released more than a decade ago. On top of that, OpenDCL gives lisp developers the power of a modern event-driven user interface that can put their lisp plugins on the same playing field as plugins written in any other language. This is a powerful combination, and given lisp’s low entry cost, it is not surprising to see lisp continuing to enjoy strong support in the developer community.

Don't catch what you can't handle

Fri, 07 Feb 2014 00:10:41 +0000

One of the cardinal rules of C++ exception handling is “don’t catch what you can’t handle”. Of course there are always, er, exceptions to the rule, but the basic principle always holds. The consequences of violating the rule are less severe in the .NET world, but even there it’s a good rule of thumb.

LspLoad now supports Bricscad V14 and ZWCAD+ 2014

Fri, 01 Nov 2013 10:48:12 +0000

I have updated the automatic lisp loader modules (LspLoad.zip on my freebies page) to support Bricscad V14 and ZWCAD+ 2014. Note that the source code for Lspload is also available.

LspLoad Updated for AutoCAD 2014 and Bricscad 13 64-bit

Sat, 13 Apr 2013 20:58:40 +0000

The automatic lisp loader modules (LspLoad.zip on my freebies page) have been updated to add support for AutoCAD 2014 and Bricscad 13 64-bit. The modules are now digitally signed so that AutoCAD 2014 loads them quietly.

Turning off InfoCenter in AutoCAD 2014

Thu, 11 Apr 2013 01:50:21 +0000

The AcadInfoCenterOff.msi file on the ManuSoft Freebies page has been updated to support AutoCAD 2014 based products. Note that you must log out of Autodesk 360 if you disable the InfoCenter, else some versions of AutoCAD will crash during startup.

C++ function declaration tips

Wed, 06 Feb 2013 22:59:29 +0000

Creating and calling functions is one of the most fundamental tasks in C++ programming. The function declaration serves as the primary description of a function’s interface - or contract - with callers, thereby making it the most important piece of code documentation. A good function declaration should convey as much information as possible. I’m sure an entire book could be written on the topic of function interface design, but I’ll just touch briefly on a few factors to consider when designing a function’s interface.

Using /delayload to specify dependent DLL path

Sat, 26 Jan 2013 01:03:48 +0000

Let’s say you have an ObjectARX module with an implicit dependency on another DLL. Your installer puts both your ARX module and the dependent DLL into a private application folder. Windows must be able to resolve the implicit DLL dependency at load time, otherwise it will fail to load your ARX module. Alas, Windows will not automatically search for the dependent DLL in your application folder, even though your ARX module is located there. Therefore your ARX module won’t load because the dependent DLL cannot be resolved.

QuirkyPolyline: exposing foolish programmers

Wed, 09 Jan 2013 02:38:45 +0000

In AutoCAD, the AcDbCurve class defines a general parametrized curve. On a parametrized curve, points in space are mapped to real numbers (parameters) by an arbitrary function F(p) for values of p from the curve start parameter to the curve end parameter. Defining a curve this way simplifies working with complex 3D curves because one can work in the curve’s one dimensional “parameter space” instead of the more complex three dimensional cartesian space.

RoboCache for Windows offline files cache management

Wed, 02 Jan 2013 08:50:27 +0000

I’ve written before about RoboCache, a command line utility I wrote for managing the offline files cache in Windows Vista, Windows 7, and now Windows 8. After using the utility internally for a few years, I decided that I might as well clean it up and make it available to the rest of you. RoboCache is now available at the ManuSoft web site. There is a shareware version available, and you can purchase the registered version at the ManuSoft store (cost is 25 USD for a single user license).

Polymorphic bit flags in C++

Wed, 19 Dec 2012 11:55:45 +0000

I often encounter cases in ObjectARX programming where numerous boolean flags need to be persisted as part of an AutoCAD database object. For filing and for passing around to other functions, it’s most efficient to package those bit flags into a single unsigned integer. Below is an example that demonstrates how to use a union inside a containing class that can be simultaneously used as either a single unsigned integer or as individual booleans.

Checking function return values

Thu, 30 Aug 2012 15:48:36 +0000

A lot of you are guilty of not checking return values from API function calls. I’ll bet you have a good excuse, like “it’s a lot of extra typing for no reason”, or “that function should never return an error code”.

Turning off InfoCenter (aka WSCommCntr4.exe) in AutoCAD 2013

Wed, 28 Mar 2012 00:41:37 +0000

I have updated the AcadInfoCenterOff.msi file on the ManuSoft Freebies page for AutoCAD 2013. If you’re not sure what it does or why you need it, see this previous post on the subject.

Registering an ARX/BRX module as a COM server

Tue, 11 Oct 2011 00:18:41 +0000

If you’re developing ARX modules that need to be registered as a COM server, you’re faced with some decisions about how to register them. In the old days before anyone cared about user permissions, registration could be safely accomplished at runtime, even via AutoLISP. Unfortunately runtime COM server registration just doesn’t work reliably any more under limited user accounts, not to mention registry redirection on 64-bit platforms. There is only one reliable way to register COM servers, and that’s doing it at install time under elevated privileges.

OpenDCL 6

Fri, 05 Aug 2011 14:32:27 +0000

You may not have noticed, but AutoLISP is still alive and kicking. This is evidenced by the growing community of developers and hobbyist programmers using the latest release of OpenDCL, the free graphical user interface library for AutoLISP applications. If you’re not familiar with OpenDCL, check out the newly released OpenDCL 6.

A tale of two tethers

Fri, 03 Jun 2011 13:08:15 +0000

Those of you using your Android phone as an internet connection may be paying more than you need to pay. Many phone companies here in the US charge extra to enable tethering capability, either by providing their own OEM tethering app or by enabling the phone to serve as a Wi-fi hotspot.

The MFC Balloon

Fri, 15 Apr 2011 17:24:46 +0000

The MFC version that ships with Visual Studio 2010 is known to cause major explosions in file size when you link statically. To avoid that problem, I use the Visual Studio 2008 build tools for such cases. I recently got quite a surprise when I rebuilt one such MFC application and discovered that the executable had ballooned from 400kb to 2MB in the space of one week despite only very minor changes.

BRX on Linux: Getting Started

Sun, 10 Apr 2011 11:19:35 +0000

When I heard that Bricsys had shipped Bricscad for Linux, I was anxious to get to work on supporting the Linux platform. The first order of business was getting familiar with Linux. For that, I chose Ubuntu 10.10 32-bit running on a VMWare Workstation 7.1 virtual machine hosted on my Windows 7 64-bit workstation.

ObjectARX Wizard for Visual Studio 2010

Fri, 01 Apr 2011 20:04:33 +0000

If you’re an ObjectARX programmer, you may still be using Visual Studio 2008 because you’ve been told that you must. It’s true that you need Visual Studio 2008 installed to compile native ObjectARX code, but with Daffodil you can do all your work in the Visual Studio 2010 IDE.

AutoCAD 2012 InfoCenter

Fri, 25 Mar 2011 21:44:00 +0000

If you’re upgrading to AutoCAD 2012, don’t forget to also disable InfoCenter (unless you really need it). Just download and install AcadInfoCenterOff to disable it on any version of AutoCAD or AutoCAD LT. If you already have AcadInfoCenterOff installed, you can just run a repair install to apply it to a newly installed instance of AutoCAD 2012.

Simplifying the problem: plain vanilla configuration

Sat, 26 Feb 2011 14:21:32 +0000

One of the stages in simplifying an AutoCAD software problem is to rule out (or in) third party add-ons as the cause. To do that, you’ll need a “plain vanilla” test bed configuration that consists of only the out-of-the-box components with no add-ons loaded.

Simplifying the problem: divide and conquer

Fri, 25 Feb 2011 14:08:51 +0000

When a customer reports a drawing-specific issue, the next stage in simplifying the problem is to eliminate all drawing content that has no bearing on the problem. Unless the drawing object that causes the problem is obvious and can be immediately ascertained, I use the divide-and-conquer method to zero in on the cause.

Simplifying the problem: is it the drawing?

Thu, 24 Feb 2011 13:54:13 +0000

One type of support request that I occasionally receive from CADVault users goes something like “when I create a vault, AutoCAD crashes”. I’ve learned that problems like this are usually drawing-specific, so before going any further in simplifying the problem I ask the customer to check whether the problem occurs in an empty drawing. But there’s a trick to this.

The art of simplifying the problem

Wed, 23 Feb 2011 14:06:57 +0000

One of the most important skills in resolving technical problems is not problem solving, but problem definition. Stripping a problem down to its essence often makes the solution obvious. I think this is generally true, but especially true in my experience with software tech support and tracking down software bugs.

All your base are belong to us

Mon, 24 Jan 2011 13:15:40 +0000

Excited news stories this morning about how your computer is vulnerable to attack from a phone plugged into your USB port made me chuckle. This “novel hack” involves making an Android phone mimic a USB keyboard in order to send keystrokes to the computer. Cool, but why wouldn’t a hacker just use a USB keyboard in the first place?

What's the diff?

Wed, 29 Dec 2010 16:32:31 +0000

One of the required tools in a programmer’s toolbox is a tool for comparing files. File comparison utilities have come a long way since the original Unix diff command, but this genre of utilities is still referred to as diff tools. For Windows, I use an open source diff utility called WinMerge. WinMerge includes a shell extension that makes it easy to use from within Windows Explorer.

Debugging heap corruption with PageHeap

Wed, 15 Dec 2010 12:58:33 +0000

Heap corruption bugs in C++ code can present some difficult debugging challenges. Often the actual corruption goes unnoticed until some apparently random point in the future when the corrupt memory is accessed by unrelated code. In such cases, it’s almost impossible to infer the location of the bug using typical debugging tools.

Windows offline files

Sun, 05 Dec 2010 13:20:03 +0000

Do you use the Windows offline files feature? I asked this question of some IT/CAD administrator types at Autodesk University last week, and was surprised to find that most didn’t even know what it was. In fact, of the dozen or so people I asked, only one actually used the feature.

Disable AutoCAD InfoCenter

Mon, 01 Nov 2010 23:44:38 +0000

Over the years, I and others have provided instructions for turning off the AutoCAD InfoCenter (or Communication Center in older versions). The instructions are different depending on the AutoCAD version. To make things simple, I decided to roll them all up into a single one-size-fits-all MSI file that disables InfoCenter for any and all versions of AutoCAD or AutoCAD LT in one fell swoop.

Visual Studio 2010 Migration Post Mortem

Mon, 18 Oct 2010 23:49:22 +0000

I have more or less completed the task of migrating my internal projects to Visual Studio 2010. Native C++ programmers are pretty low on the totem pole of programming coolness these days, but Microsoft did throw us a few bones. At this point I have to say I’m ambivalent overall with VS 2010, but I really like some of the architectural changes and I’m excited about the future.

Visual Studio 2010 Native Multi-Targeting

Thu, 07 Oct 2010 02:16:19 +0000

I was hoping that Microsoft would address the need to target earlier versions of Visual Studio within the Visual Studio 2010 IDE, but since they decided to punt, I tackled the problem myself. I’ve released my solution as an open source project named Daffodil for Visual Studio.

QuikPik 4.1 Adds Classic Title Bar Feature

Fri, 24 Sep 2010 22:54:28 +0000

Those of you with bad eyesight (and the rest of us throwbacks) will appreciate the new ‘Classic title bar’ feature in QuikPik 4.1. This new feature addresses AutoCAD 2009 and later versions of AutoCAD with the fancy schmancy title bar and menu bar.

The Cancel Retry Paradox

Wed, 25 Aug 2010 15:19:09 +0000

Yesterday when I attempted to install the AutoCAD 2011 service pack (er, I mean “update”), I encountered the classic UI paradox where you’re forced to choose from a set of equally undesirable choices, this time with a bonus.

I received error 1321. My choices were to retry or cancel. If I chose to retry, I got the same error again. If I chose to cancel, I got a bonus question: it asked whether I really wanted to cancel. I had to lie and choose yes, otherwise I would be trapped in an infinite loop.

Missing Language Pack DWG File Repair

Thu, 22 Jul 2010 00:11:46 +0000

I wrote before about corrupt text causing bogus “Missing Language Pack” warnings in AutoCAD. That case prompted me to write a file repair utility. However, since the case appeared to be isolated, I never released the utility to the public.

The problem has been rearing its ugly head again, so I decided to dust off the original code and release it. The repair utility is now available on the freebies page (look for CleanLanguage.zip) for AutoCAD 2007 and later versions of AutoCAD. I have not tested any recent cases, so I can’t be sure it is the same problem. If you try the utility, please report your results by leaving a comment here.

Using VC 7 build tools in Visual Studio 2010

Thu, 24 Jun 2010 16:13:38 +0000

[Update: See Visual Studio 2010 Native Multi-Targeting]

Developers, if you use VC Build Hook and/or need the same capability in Visual Studio 2010, please let Microsoft know by voting for a fix. I’ve written before (and here) about the problem. I think it is possible to hack a third party solution, but by far the best solution is for Microsoft to add back the ability to produce ANSI response files in service pack 1.

GlowCode Success Story

Sat, 12 Jun 2010 18:56:33 +0000

I use GlowCode for profiling ObjectARX applications. As far as I know, this is the only profiler that works with AutoCAD. What makes GlowCode special is that it can instrument code on the fly, including a monster like AutoCAD. It has a clunky interface that takes some patience to figure out, but it’s a lifesaver when you need it.

Visual Studio 2010 Ships

Mon, 12 Apr 2010 20:34:40 +0000

Visual Studio 2010 shipped today accompanied by .NET Framework 4.0. I blogged before about the switch to using the MSBuild build system, and how that theoretically could be helpful in targeting multiple AutoCAD versions from the same solution. The shipping VS 2010 does not support non-Unicode response files, so out-of-the-box it cannot target VC 7.0 (for AutoCAD 2006 and earlier). When time permits, I’m planning to see if I can find a workaround; in the meantime, I’ll continue to use VS 2008 for ObjectARX.

Port Your ObjectARX Code to 64 Bit

Thu, 11 Mar 2010 23:08:00 +0000

AutoCAD versions since AutoCAD 2008 (and since AutoCAD LT 2009) have included both 32 bit and 64 bit flavors on the same media. If you install on a 64 bit Windows system, you get the 64 bit AutoCAD; otherwise you get the 32 bit AutoCAD. The 64 bit AutoCAD can take advantage of as much memory as you can throw at it, whereas the 32 bit version is limited to 2 GB (3 GB if you cheat). They should be otherwise identical in theory, but in practice there are major differences.

One big difference is VBA. Microsoft put VBA out to pasture many years ago when they introduced the .NET framework, so there will never be a 64 bit version of VBA. Autodesk had to resort to a seriously inefficient kludge to get it to work at all in the 64 bit flavor of AutoCAD (VBA has to run in a separate 32 bit process, which makes typical applications two orders of magnitude slower).

The other big difference is that any third party ObjectARX applications must be installed for the correct architecture. A 32 bit ObjectARX application will not work in a 64 bit AutoCAD. [Note that .NET (or “managed”) applications typically work fine in both architectures – I’m referring to native C++ ObjectARX applications only.]

On the Autodesk discussion groups, many people ask how they can install the 32 bit version of AutoCAD on their new 64 bit operating system. Why would they want to do that? Almost always because they need to use an application that is only available for 32 bit AutoCAD architectures, or because they discover that their VBA applications become unbearably slow.

It is possible, with some hacking of the AutoCAD installation database, to install the 32 bit flavor of AutoCAD on a 64 bit system, but I don’t recommend that. There is just no excuse any more to not support the 64 bit architecture. If you find yourself in this situation, put pressure on the developer of the application to get it ported.

In fact, if you rely on an application that hasn’t been ported to the 64 bit architecture, I’d like to hear from you. Add a comment to this post and let me know the name of the application. If you are a vendor or developer that has not yet ported your 32 bit application, please contact me – I will gladly port it for you. Even large applications can typically be ported in several hours.

BTW, I am well aware that even Autodesk is guilty of not supporting 64 bit platforms in some of its vertical market AutoCAD versions (and corresponding object enablers). I certainly hope they remedy that situation in the next release cycle.

Visual Studio 2010 and VC Build Hook

Mon, 11 Jan 2010 20:32:00 +0000

[Update: See Visual Studio 2010 Native Multi-Targeting]

Many of you use my VC Build Hook utility to target multiple versions of AutoCAD from a single solution in Visual Studio 2008. Visual Studio 2010 now includes a new feature called native multi-targeting that performs the same function as VC Build Hook. The new feature works great for using build tools back to VC 7.1, but it does not work with VC 7, which is required for targeting AutoCAD versions 2006 and earlier.

Automatic LISP Loading

Thu, 24 Dec 2009 12:12:00 +0000

There are a myriad of ways to load AutoLISP applications in AutoCAD, including acaddoc.lsp, an .mnl file, the Startup Suite, and manually by various means. For application developers wishing to deploy their applications to others, all of these methods have drawbacks. The ideal solution should be easy to implement in an installation program, require minimal or zero changes to the user’s AutoCAD configuration, work the same way across all versions of AutoCAD, and easily undone when the application is uninstalled.

ArxDbg Utility

Wed, 23 Sep 2009 18:31:00 +0000

ArxDbg is the name of a sample project that has been included with the ObjectARX SDK for many years. It’s primary purpose is to demonstrate how to use the ObjectARX API, but it is a complete free-standing utility in its own right. ObjectARX programmers often use this utility during development for testing and exercising their application code, but it can be useful to anybody, not just programmers.

AutoCAD Missing Language Pack Drawing File Corruption

Mon, 03 Aug 2009 13:38:00 +0000

I’ve been chasing a drawing corruption problem on behalf of a customer. The problem manifests itself by causing a “Missing Language Pack” dialog to display when the drawing is opened (but only in Windows XP with no language packs installed – my Vista installation apparently has all the language packs installed). Installing the language packs “fixes” the problem, in that the drawing files open without error.

However, the real problem is that some drawing objects were corrupted in memory, and corrupt data was subsequently written to the .dwg file. My customer thinks the corruption might be linked to a virus that they were infected with (and have since eliminated). I have a copy of the virus for testing, but I have not been able to catch it in the act of corrupting an open drawing file. Therefore, I cannot conclusively link the virus with the corruption.

So, I need your help. Have you recently noticed a “Missing Language Pack” dialog appearing in drawing files that have opened fine in the past? Has your virus scanner recently detected an AutoCAD related virus? If you have, please send me an email describing your situation and AutoCAD versions involved. I would like to determine conclusively whether the virus is causing drawing file corruption, and if so, whether the corruption is always in the same location of the drawing file.

[Update: Autodesk has released a technical document with information about the virus. See also Shaan Hurley’s blog post.]

If you want it done right...

Wed, 08 Jul 2009 09:05:00 +0000

I’ve proved once again that if you want it done right, you have to do it yourself. The ManuSoft web site is fully functional again after my longtime ISP had a major network meltdown. I waited for two weeks for them to repair it, then finally moved to a different provider. The new provider’s promised “24/7 tech support” turned out to mean “24 hours to respond, 7 days to fix” every problem, not to mention that I would need to provide step by step instructions to their techs so they could configure the server the way I needed. After two weeks of that, I gave up and configured my own server and now host it myself.

Let this be a warning to all of you hosting web sites with reputable providers, or storing your data somewhere in the cloud. I paid big bucks every month to my old provider for secure servers, redundant power supplies, managed and air conditioned server rooms, nightly backups, 99% uptime, etc., but they still lost everything. Almost a month later they still haven’t restored their customers’ data. Luckily, I make my own backups.

Disable InfoCenter in AutoCAD 2010

Mon, 30 Mar 2009 18:13:00 +0000

[Update: See Disable AutoCAD InfoCenter]

In case you missed it, Tony Tanzillo has posted instructions for disabling the InfoCenter in AutoCAD 2010. AutoCAD 2010 starts faster when the InfoCenter is disabled.

To make it easy, I’ve created an AutoLISP file that defines commands named DisableInfoCenter and EnableInfoCenter:

ObjectARX 2010: Dealing With Missing Exports

Sat, 28 Mar 2009 16:54:00 +0000

In the new ObjectARX 2010 SDK, Autodesk has added some new virtual member functions that are not exported as they should be. For example, the AcGiFaceData class has had two new virtual functions added for setting and getting the face transparency:

class AcGiFaceData: public AcRxObject
{
//[… deleted for brevity]
ACDB_PORT virtual AcDbObjectId materials() const;
ACDB_PORT virtual AcGiMapper mappers() const
virtual void setTransparency(const AcCmTransparency transparency);
virtual AcCmTransparency transparency() const
private:
AcGiImpFaceData mpAcGiImpFaceData;
};

As you can see, whoever added the new functions neglected to prefix them with the ACDB_PORT macro. ACDB_PORT evaluates to __declspec(export), which tells the compiler to export the function. Since the macro is missing, the new functions are not exported from acdb18.dll.

Since these are virtual functions, you won’t have any problems calling them through a pointer to an AcGiFaceData object that was constructed by AutoCAD. The problem arises when you derive a class from AcGiFaceData. Since the functions are not exported, the linker has no way of resolving their address for creating the virtual function table of your derived class. This results in linker errors:

acrxEntryPoint.obj : error LNK2001: unresolved external symbol “public: virtual void __thiscall AcGiFaceData::setTransparency(class AcCmTransparency const )” (?setTransparency@AcGiFaceData@@UAEXPBVAcCmTransparency@@@Z)
acrxEntryPoint.obj : error LNK2001: unresolved external symbol “public: virtual class AcCmTransparency * __thiscall AcGiFaceData::transparency(void)const " (?transparency@AcGiFaceData@@UBEPAVAcCmTransparency@@XZ)
Following is an example that results in these errors:

class AcGiFaceDataEx: public AcGiFaceData
{
public:
AcGiFaceDataEx() {}
~AcGiFaceDataEx() {}
} Test;

The only solution is to provide an implementation of the missing functions. In this case, it could be accomplished by something like this:

class AcGiFaceDataEx: public AcGiFaceData
{
AcCmTransparency mpTransparency;
public:
AcGiFaceDataEx() : mpTransparency( NULL ) {}
~AcGiFaceDataEx() { delete mpTransparency; }
virtual void setTransparency(const AcCmTransparency transparency)
{
delete mpTransparency;
mpTransparency = (transparency? new AcCmTransparency( transparency ) : NULL);
}
virtual AcCmTransparency transparency() const { return mpTransparency; }
} Test;
This will fix the linker errors, but there is no guarantee that it will work as intended. AutoCAD might access its internal transparency value directly without calling through the member functions, which means it would never “see” the transparency set through the replacement member functions. Furthermore, the addition of the new pointer member changes the size of the class, which causes AcGiFaceDataEx arrays to have a different memory footprint than AcGiFaceData arrays. Lastly, what if Autodesk fixes the problem in a future AutoCAD service pack?

The ideal solution should not change the size of the class. It should check at runtime whether the function is exported, then use the exported function if it exists. That way, code that is written now will use the exported function if and when it becomes available in a future version of AutoCAD. When the function is not exported, an alternate implementation must be provided. This is not an unusual scenario, and the solution I present for the specific case of AcGiFaceData can be adapted to the more general problem.

In the AcGiFaceData case, the missing functions are virtual functions. Knowing this, it is possible to use a trick to get the address of the real function. In the code below, the function getAcGiFaceData_vtable() constructs a temporary AcGiFaceData object, from which it extracts a pointer to the object’s virtual function table. The virtual function table is just an array of function pointers, so the address of the desired function can be obtained by indexing into the virtual function table. The question is, how far? By counting virtual functions and data members starting from the top of the class hierarchy: in this case, 6 virtual functions in AcRxObject plus 16 virtual functions in AcGiFaceData = 22.

Note that obtaining a function pointer this way relies on Visual C++ implementation details, but this is safe to do since all ObjectARX modules must be compiled in Visual C++.

Following is my solution to the missing AcGiFaceData functions:

#pragma warning(push)
#pragma warning(disable: 4608)
template < typename Src, typename Dest >
Dest force_cast( Src src )
{
union _convertor { Dest d; Src s; _convertor() : d(0), s(0) {} } convertor;
convertor.s = src;
return convertor.d;
}
#pragma warning(pop)

static FARPROC getAcGiFaceData_vtable()
{
static FARPROC rfVTable = (FARPROC**)&AcGiFaceData();
return (rfVTable? rfVTable : NULL);
}

void AcGiFaceData::setTransparency( const AcCmTransparency transparency )
{
typedef void (AcGiFaceData::F_setTransparency)( const AcCmTransparency );
static F_setTransparency pfSetTransparency = force_cast< FARPROC, F_setTransparency >(GetProcAddress( GetModuleHandleA( “acdb18.dll”), “?setTransparency@AcGiFaceData@@UEAAXPEBVAcCmTransparency@@@Z” ));
if( !pfSetTransparency )
{
static FARPROC rfVTable = getAcGiFaceData_vtable();
if( rfVTable )
pfSetTransparency = force_cast< FARPROC, F_setTransparency >( rfVTable[22] );
}
if( pfSetTransparency )
(this->pfSetTransparency)( transparency );
}

AcCmTransparency AcGiFaceData::transparency() const
{
typedef AcCmTransparency (AcGiFaceData::F_transparency)() const;
static F_transparency pfTransparency = force_cast< FARPROC, F_transparency >(GetProcAddress( GetModuleHandleA( “acdb18.dll”), “?transparency@AcGiFaceData@@UEBAPEAVAcCmTransparency@@XZ” ));
if( !pfTransparency )
{
static FARPROC rfVTable = getAcGiFaceData_vtable();
if( rfVTable )
pfTransparency = force_cast< FARPROC, F_transparency >( rfVTable[23] );
}
if( pfTransparency )
return (this->*pfTransparency)();
return NULL;
}

What's New in the AutoCAD 2010 EULA

Wed, 25 Mar 2009 00:55:00 +0000

Everyone else is discussing all the cool new features in AutoCAD 2010, so I decided to have a look at what’s new in the EULA (End User License Agreement). I compared the AutoCAD 2010 EULA for US/Canada to the AutoCAD 2009 EULA. I won’t divulge the process I used to automate the comparison, because the odds are pretty good that I violated the EULA somewhere along the way, and I want plausible deniability.

The first change I noticed is that the AutoCAD 2010 EULA contains more shouting. The 2009 EULA started out in a fairly mellow mixed case with a few shouts thrown in for effect, but the 2010 EULA dispenses with the lower case and launches right into a multi-paragraph avalanche of screaming block letters. Apparently nobody was listening, so they turned up the volume.

Substantively, there are a number of very interesting changes. The following was added to the preamble:

SOFTWARE OBTAINED FROM THIRD PARTIES THAT HAVE NOT BEEN AUTHORIZED OR ALLOWED BY AUTODESK, DIRECTLY OR INDIRECTLY, TO SUPPLY SOFTWARE IS LIKELY TO HAVE BEEN MADE AVAILABLE IN VIOLATION OF AUTODESK’S RIGHTS. IN SUCH AN EVENT, AUTODESK IS NOT OBLIGATED TO ISSUE AN ACTIVATION CODE OR OTHERWISE PERMIT YOU TO INSTALL OR USE THE SOFTWARE.

Next time you’re eyeing that used copy of AutoCAD 2010 on eBay, be warned that Autodesk is not obligated to permit you to install or use the software. They don’t come right out and say that they won’t allow it, so maybe they won’t mind – but then what’s the point of including this clause? Tim Vernor won’t be very happy about this change.

Moving along, I see that they added a definition for “Uninstall”, defining it as “to destroy or remove”. The definition of “User Documentation” was very slightly changed from “…after You acquire or Install the Software…” to “…when or after You acquire or Install the Software…”. Incidentally, did you know that Autodesk considers an AutoCAD reseller’s invoice to be “user documentation”?

Rounding out changes in definitions is a change in the definition of “You”. Yes, Autodesk has redefined “You” whether “you” like it or not.

I could go on and on about small wording changes, and while it would be interesting to contemplate why each change was made (and how many scheming lawyers it took to do it), we’d risk missing the forest for the trees.

Section 2.1, “License Grant”, contains ominous new language. The following has been added:

You may Access the application programming interfaces that may be included with or in the Software or otherwise available from Autodesk for use with the Software (“API’s”) to develop programs, modules, components or functionality that (i) are compatible with and are used and/or interfaced with the Software and (ii) contribute significant value-added functionality or enhancements to the Software (“API Modules”) provided You may Install and Access such API Modules solely on Computers where a licensed copy of the Software is also installed and further provided such Installation and Access is solely in connection with Your Installation and Access of the Software and solely for Your internal business needs. You may not redistribute all or any portion of an API Module.

Read that again. That’s right, you may not write any “programs, modules, components, or functionality” unless they “contribute significant value-added functionality or enhancements” to AutoCAD. Furthermore, if you do manage to write a program that adds significant functionality, you may not redistribute all or any part of it. What are those guys smoking out there in California?

Finally at the end of section 2.1, they changed “No license is granted under the terms of this Agreement if You did not lawfully acquire the Software” to “No license is granted under the terms of this Agreement if You did not lawfully acquire the Software from Autodesk or from a third party who has been permitted or authorized by Autodesk either directly or indirectly to supply the Software”. Take that Tim Vernor!

In another nod to the Vernor case, section 2.3, “Upgrades”, adds a new requirement to “destroy all Autodesk Materials relating to the Previous Version or, upon request by Autodesk, return all such Autodesk Materials relating to the Previous Version to Autodesk or the company from which they were acquired”. This is important language that could persuade a court to view an AutoCAD purchase as a license instead of a sale, thereby giving Autodesk the power to control the secondary market.

Interestingly, section 2.4, “Crossgrades”, requires that the previous software be uninstalled within 60 days, but has no requirement that it be destroyed. However, new language in section 2.7, “Termination”, which requires the software to be destroyed “upon termination of the license grant or this Agreement”, apparently covers both cases.

A funny change in section 3.2.3, “Transfers”, appears to close a loophole. The AutoCAD 2009 EULA disallowed transfers to “any other person”; the AutoCAD 2010 EULA disallows transfers to “any other person or legal entity”. Considering a license transfer? Make sure it’s to an illegal entity!

Section 4, “ALL RIGHTS RESERVED”, was rewritten. The rewrite introduced a grammatical error (“and You have not other rights”), but otherwise I don’t see that much changed. It still ends with the now familiar directive that “The Software and User Documentation are licensed, not sold."

Finally, the infamous “audit clause” has been revised. Not the way you may have hoped, I’m sad to report. Luckily the change was a minor one that doesn’t make the clause any more overbearing than it already was.

Isn’t change wonderful?

Autodesk Design Review 2010 Snake Oil Alert

Thu, 12 Feb 2009 14:35:00 +0000

From a new features overview of Autodesk Design Review 2010 comes the following snake oil claim:

Digital Signatures
To help secure your data, you can now digitally sign DWFx files.

As I’ve explained before, digital signatures do not provide data security; they simply authenticate the person that applied the signature. Digital signatures are a welcome feature with many potential uses, but data security is not one of them.

Autodesk Discussion Group Facelift Offer

Wed, 28 Jan 2009 12:00:00 +0000

My participation in the Autodesk discussion groups has been severely curtailed since the notorious “upgrade” a few months ago. One of the many problems introduced by the upgrade is the loss of formatting. It’s now virtually impossible to post messages that include inline AutoLISP or ObjectARX code without them being reformatted into unreadable garbage. Even attaching the code as a file is difficult (the “solution” is to rename files with a .txt extension!) As a result, many queries for programming help go unanswered. Autodesk has made an attempt to provide a fix, but a survey of the posts in any of the programming groups shows that it’s not working.

[Thread has been removed by Autodesk, so link was changed to point to archived thread.]

The recently announced layoffs and related cost cutting measures at Autodesk have dimmed my hopes for a resolution. Therefore, I’ve decided to offer my services to fix the problem. Autodesk, I’m offering to donate my time to fix your discussion group software. Just give me access to a development and testing platform, and the right to modify or rewrite the code.

Readers, can I get an “Amen”?

AECOPEN Utility

Sat, 24 Jan 2009 17:07:00 +0000

James Maeding of Hunsaker & Associates contacted me recently about an irritating problem that his users have with the AECOPEN command in Land Desktop. The AECOPEN command replaces the core AutoCAD OPEN command in AEC verticals. The problem they have is that AECOPEN displays an initial project dialog that requires users to press a [Browse] button to open the file browser dialog. Since they want to browse for a file every time they use the AECOPEN command, James wondered if I could create some code to automatically “press” the Browse button every time the AECOPEN command is issued.

I whipped up a little utility for AutoCAD 2007-2009 based products to do what James wanted, and it is now available on my freebies page as AecAutoOpen.zip. When the ARX module is loaded, AECOPEN behaves as if the user had immediately pressed the [Browse] button on the project dialog. If the [Ctrl] key is pressed, AECOPEN reverts to its original behavior.

Why not just use the built in OPEN command instead? The AECOPEN command has some important side effects, according to James.

Missing Menu Madness

Mon, 22 Dec 2008 18:15:00 +0000

One of my many complaints about about the CUI system introduced in AutoCAD 2006 is that it's not very friendly to third party developers. In my opinion, it's not very friendly to end users either, but I digress...

One example of the unfriendly CUI is the case where a third party application installs a partial menu. In the pre-CUI days, adding a partial menu was an easy way to add an application specific menu to AutoCAD without making any changes to the end user's existing menu files. If the application was later uninstalled, the uninstall script could remove its menu and clean up the registry, leaving no trace behind. CUI breaks that scenario.

Design File Locking and Snake Oil Security

Sat, 06 Dec 2008 14:52:00 +0000

The increased sharing of electronic CAD data (ala BIM) holds a lot of promise, but it also exposes companies and individuals to additional liability and risk. This additional risk is coming into focus more and more as actual cases of costly legal battles confront engineers and architects.

The June 2008 AUGI wishlist results contain “Design File Locking” as the top wish by a substantial margin, and Shaan Hurley lists it as number 3 in the AU 2008 AutoCAD wish list. Clearly, interest in file and IP security has been growing steadily.

As demand for IP security grows, there are sure to be snake oil security vendors trying to cash in on it. I received a spam email a few days ago from SafeNet, Inc. promising “a cost-effective and easy to integrate solution that provides reliable and effective security through the use of digital signatures.” Whenever I see such statements with a long string of buzzwords, my snake oil alarm goes on alert. Digital signatures are for authentication and establishing trust – they cannot and do not provide “reliable and effective security”, although I suppose they could be used by a system that does.

In the last year or two, a number of companies have claimed to market software that “secures” AutoCAD DWG files. When I see such a claim, it invariably refers to software that creates an anonymous unequally scaled MINSERT entity. These can be created or “exploded” with a few lines of AutoLISP code. Frequently these companies claim to “encrypt” the drawing, which may sound sexy, but is an outright lie. If this is a level of “security” that meets your needs, at least use one of the many free versions posted throughout the internet (DETER.VLX from DotSoft is one I know of).

There are solutions, but they always require changes in the workflow process that involve difficult tradeoffs and careful evaluation of what is technically feasible and practical versus the costs of implementing the changes. There is no such thing as installing a single piece of software to instantly solve the problem. If you are looking for ways to protect intellectual property in your drawing files, don’t be fooled by snake oil security vendors.

Disclaimer: One of my hats is the president of CADLock, Inc., makers of CADVault for AutoCAD.

Propagandapedia

Wed, 15 Oct 2008 17:58:00 +0000

Did you ever wonder what press release writers do in their spare time? Given Autodesk's recent trademark litigation with SolidWorks and related efforts by Autodesk to trademark "DWG", and given the fact that US Patent and Trademark Office (USPTO) trademark examiners are known to use Wikipedia during their research, it doesn't take an evil genius to realize that a little subversive editing here and there might be helpful to the corporate cause. So, I decided to use Wikiscanner to go spelunking through the labyrinth of Wikipedia editing history to see if I could unearth any nuggets.

OpenDCL Quick Intro

Sun, 24 Aug 2008 14:42:00 +0000

If you’re an AutoLISP programmer, you’ve probably heard about OpenDCL. Maybe you’ve even checked it out, but it looked complicated and you weren’t sure whether it was worth the trouble to learn how to use it. Either way, do yourself a favor and spend 10 minutes to go through the following 10-step quick introduction to OpenDCL.

Download and install OpenDCL Studio. Select the latest version in your desired language (ENU in the filename means US English). The download is an .msi file that can be cleanly uninstalled afterward.
Start AutoCAD (2004 or later). Use the APPLOAD command to load _MasterDemo.lsp from the OpenDCL Studio samples folder (it will be located in a language subfolder of the main OpenDCL Studio folder). When you close the APPLOAD dialog, the OpenDCL ‘MasterDemo’ dockable form will appear.
Click on the [ListView] button to run the ListView sample. The ListView sample is very simple and will demonstrate some basic principles of OpenDCL. Leave it running as you proceed through the following steps.
Locate and open ListView.lsp in the OpenDCL Studio samples folder. ListView.lsp contains all the code for the ListView sample. Look for the c:ListViewDlg_Close_Clicked function defined near the end of that file. That function is called an “event handler”, and it is the lisp function that is executed when the [Close] button is pressed. The event handler for the [Close] button simply closes the dialog. The c:ListViewDlg_OnInitialize event handler function initializes the controls on the dialog before it is displayed.
Locate and open ListView.odcl in the OpenDCL Studio samples folder. Files with an .odcl extension can be opened and edited in OpenDCL Studio. OpenDCL Studio is used to design the user interface elements in an OpenDCL project. In the project tree pane, open the ‘Modal Forms’ folder, then double click on ListViewDlg. The ListView form will be displayed in design mode.
Click on the [Close] button on the ListView form. In the font toolbar at the top of the editor, press the [B] button to make the font bold. Notice that the button’s caption becomes bold. In the ‘Properties’ pane, double click on the ‘Height’ property value and change it to 20. Press [Enter] to apply the new value. Use your mouse to drag the bottom of the button in design view to resize it dynamically.
Leaving OpenDCL Studio open, switch back to AutoCAD. Resize the ListView dialog, and notice how the controls it contains are also resized. Now switch back to OpenDCL Studio, make sure the [Close] button is selected, then click in the right column of the ‘(Wizard)’ property in the Properties pane (or right click on the button control and select ‘Properties’ in the control’s context menu). In the Control Properties Wizard, the Geometry tab shows that the button’s “Left Side Alignment” has been set to “Offset From Center of Dialog” and it’s “Top Side Alignment” has been set to “Offset From Bottom Edge”. Once these properties are set, no additional code is needed for the control to react correctly when the dialog is resized.
Exit AutoCAD, then restart. Enter the OPENDCL command. This command demand-loads the OpenDCL Runtime using AutoCAD demand loading mechanism. The OpenDCL Runtime must be loaded before the OpenDCL functions will work. The OpenDCL Studio installation includes OpenDCL Runtime, so it already exists on your computer.
If you are developing an application for use by others, you’ll need to download and distribute the OpenDCL Runtime along with your application. This is best done by incorporating the OpenDCL Runtime merge module for your language directly into your own application’s installation script. Alternatively, you can distribute the standalone OpenDCL Runtime .msi file for your language, or publish the URL where end users can download the latest version.
Switch back to OpenDCL Studio and double click on the [Close] button control. Intelligent help displays all the properties, methods, and events of the selected control, including their AutoLISP syntax. Click on a property, method, or event in the left pane to see detailed information for it.

Once you complete these ten steps, you are only a few minutes away from creating a fully functional OpenDCL application. Give it a try!

Debugging ObjectARX: Break on Exception

Mon, 12 May 2008 11:11:00 +0000

I have presented a class entitled High Octane ObjectARX at Autodesk University the past two years. In 2006 the focus was on project organization, and last year I focused more on techniques for supporting multiple versions of AutoCAD with a single Visual Studio solution, touching briefly on testing and profiling. For 2008 I plan to focus on debugging.

The Day the ObjectARX SDK Died

Thu, 27 Mar 2008 15:09:00 +0000

Like that day almost 50 years ago, could today be the day that ObjectARX has died?

There have been a flurry of posts in the ObjectARX discussion group about problems downloading the new ObjectARX 2009 SDK. At first I dismissed the problems as new release hiccups, and expected things to get resolved in short order. Seeing that there were no new complaints this morning, I headed over to http://www.objectarx.com/ to download the new ObjectARX 2009 SDK. Instead of the new ObjectARX 2009 SDK, I received the following:

Periscope Speaks HTML

Sat, 22 Dec 2007 17:06:00 +0000

I hit the jackpot at Radio Shack, so I’m back early from my last minute Christmas shopping today. That means I have time to tell you about the new Periscope 4.0 just released this week, in case you’re looking for a last minute stocking stuffer for that CAD geek friend of yours that already has everything.

Periscope shows information about the entity beneath your AutoCAD cursor in a tooltip window (“scope window”) as you hover over an entity in AutoCAD. Periscope 3 added a COM interface that made it very easy to program a custom “extender” that added to or modified the displayed entity information. Periscope 4.0 goes even farther – it uses an excellent open source class by Eugene Pustovoyt to render simple HTML in the scope window. Custom extenders for Periscope 4.0 can now use selected HTML tags to format and beautify their output.

If you’re upgrading from a previous version of Periscope and you already use a custom extender, note that you will need to make a few minor modifications to your extender code. In addition to referencing the new type library (now version 4.0), you’ll need to add a new “GSMarker” argument to your extender’s AddScopeText event handler.

I’ve added a new .NET sample extender to show how easy it is to write a Periscope extender in .NET via COM interop. AutoCAD Map 3D 2008 and Topobase 2008 users, check out the commented code in the .NET sample extender to see how you can display feature data in the scope window!

Happy Holidays!

Blog Posts Immortalized

Sat, 15 Dec 2007 19:18:00 +0000

I’ve created a compendium of two previous series of blog posts on my web site for posterity (and easier reading):
I’ll take web sites for $200, Alex
Digital Signatures in the CAD Industry

Digital Signatures: Practical Guidelines

Mon, 10 Dec 2007 21:17:00 +0000

We use digital signatures every time we visit a secure web site. Visiting a secure web site involves an authentication process that includes verifying the identity of the server by ensuring that its digital certificate, or “server certificate”, is signed by a trusted certificate authority. This verification process might involve verifying an entire chain of certificates from the actual server certificate up through one or more intermediate certificate authorities and ending with a trusted root certificate authority. This all takes place quickly and automatically before the web page is displayed in your web browser because the web browser includes built in logic to do this work without any user interaction. More importantly, the web browser warns us when the server certificate is expired or invalid.

The biggest obstacle when using digital certificates in a CAD environment today is not creating them, but easily and automatically verifying them at the receiving end. Even in a completely digital distribution system where everybody works from the CAD model, the various software tools we use to view and work with the model do not handle digital signature verification automatically in a standardized way. As long as downstream consumers of CAD data cannot easily and automatically ensure the trustworthiness of digital data, they will continue to rely on handwritten signatures on paper.

A second obstacle to the use of digital signatures is the difficulty in accepting that digitally signed data is only trustworthy while it remains in digital format, and therefore the digital file is the “record” document. There is substantial social inertia that must be overcome before a digital document can gain the same amount of trust as a paper document. Engineers and architects must deal with the specter of previously hidden meta data in their CAD models becoming part of their signed document, thereby exposing them to new liabilities that don’t exist with paper drawings. Construction supervisors must learn to refer to the CAD model instead of relying on hardcopy blueprints when resolving disputes or establishing responsibility for errors. Here I think it should be noted that the use of a digitally signed model does not preclude the creation of hardcopy blueprints. Those can be created and “wet stamped” separately at the same time the CAD model is signed digitally; or they can be created in the field for reference without any signature at all.

AutoCAD has supported digital signatures for several years, but using the built in functionality is limited to only individual DWG files, lacks support for co-signing (more than one person signing), and forces the signed document to remain in the proprietary DWG format or lose its signature. These problems can be worked around by using third party tools, but doing so requires recipients to use the same tools.

Over the past few years, many government plan review bodies have amended laws and administrative rules to accommodate digital signatures as part of the plan review process. Without standardization, however, organizations still struggle to effect the necessary changes in their workflow. A lack of uniformity in terminology from one set of regulations to another adds to the confusion. If you are involved in amending or creating rules or regulations that enable the use of digital signatures, you should use generic and well defined terms of art in the regulations, but supplement these with practical guidelines that mention specific technologies, software tools, and file formats that will meet the legal requirements and that you are capable of working with.

If you are an architect, engineer, or CAD manager working to implement digital signatures into your firm’s workflow, there are some concrete steps you can take to make the task easier. Start by segregating your distribution network into “digital-only” and “hardcopy” classes of downstream users. Begin the transition with the digital-only part of the network (perhaps only the plan reviewing authority, for example). Next, decide which file format to use for your digital “documents”. Rather than signing CAD files, many companies start by signing 2D output files such as PDF, DWFx, or XPS. These files are essentially digital versions of the hardcopy documents, so they are more familiar to a wider audience and avoid some of the liability issues of exposing formerly hidden metadata that lives within the CAD model files.

You’ll need to obtain a digital ID and establish internal policies for storing and accessing the digital ID so that only the owner of the digital ID ever has access to the private key. Windows includes a built in certificate manager that you can use to view and manage your digital IDs. To start the certificate manager, run the certmgr.msc management console by entering its name in the Start -> Run command window. Your digital certificate will be installed in your personal certificates folder along with a link to the private key stored in the Windows secure key repository. Make a backup of the digital ID by exporting it to a password protected PFX file. Once a backup is made, the private key should be marked as not exportable to further secure it.

If you want to create digitally signed AutoCAD DWG files, you can use the digital signature feature of AutoCAD to sign a drawing file either while saving it or after it is saved. You should also consider subscribing to a commercial time service (see What time is it?) to ensure that your signatures are accompanied by a reliable time stamp in case your digital ID becomes compromised at some point in the future. Third party tools like CADVault for AutoCAD even make it possible for different people to sign different parts of the CAD model, but such advanced functionality is not needed in most cases.

If you use different CAD software that does not support digital signatures natively, or if you choose to sign only the secondary files produced by exporting your CAD model to a different format, then you will need to use either tools specific to that format or third party tools that work with files of any format. Adobe Acrobat (PDF) and Microsoft’s free XPS Viewer both provide integrated digital signature tools that use the same digital IDs that you would use in AutoCAD, Internet Explorer, or Outlook/Windows Mail, and both applications are easy for recipients to obtain and use.

Another popular tool for managing digital IDs and signing files is an open source tool called GnuPG. GnuPG utilizes encryption and key storage standards called OpenPGP. OpenPGP is not compatible with the X.509 standard used by Windows and many other encryption tools, however it is an attractive alternative when cost or closed source tools are a prohibitive barrier. There are many other digital signature resources available on the internet for those wanting more information, or needing specialized tools.

Unfortunately, no matter what software tools or file formats you use, today’s CAD software and document viewers still do not provide the user experience that web browsers do when it comes to digital signatures. These problems can be overcome by end users, but ultimately they need to be addressed by the makers of the software tools we use. Software for handling digital data will need better user interfaces that allow users to easily specify which digital signatures should be trusted for which purposes, and provide requisite warnings when a document should not be trusted. I am confident that these improvements will come in the future, especially as more companies begin to use digital signatures in their workflow and demand for better digital signature support rises.

If you already use digital signatures with your CAD related documents, I would like to hear about it. Please leave a comment about your experiences, whether good or bad!

Digital Signatures: Under the Hood

Mon, 10 Dec 2007 21:15:00 +0000

The basic requirements of a digital signature are that it must uniquely identify the signatory, it must be independently verifiable, and it must be invalidated if the signed data has changed. To understand how these objectives are achieved, let’s start with the foundation of modern digital signature technology: public key encryption and the public key infrastructure, or PKI.

In public key encryption, a “key pair” consists of two parts: a public key and a private key. In simplistic terms, the public key is mathematically derived from the randomly generated private key using an algorithm known as a “one way function”. A one way function makes it easy to calculate a public key if the private key is known, but extremely difficult to deduce the private key if the public key is known. The end result is a secret private key and an openly shared public key that are mathematically related in such a way that the public key can be used to decrypt data that was encrypted with the private key, and the private key can be used to decrypt data that was encrypted with the public key.

This interesting property of such a key pair gives rise to a number of useful capabilities. In the case of digital signatures, the act of signing data is essentially nothing more complicated than encrypting the data with a private key. If the data can be decrypted successfully with the signer’s public key, then only the signer’s private key could have been used to do the encrypting. In practice, this process is simplified so that the signer encrypts only a secure hash, or checksum, of the data to be signed. The recipient then calculates the hash from the raw data and compares the result with the “signed” hash after it is decrypted. If the values match, the digital signature and data are validated.

For this process to work properly, there need to be standard ways to package information about the algorithms used, and to provide important information about the keys themselves. This need is fulfilled by digital certificates. A digital certificate is a file or block of memory containing a public key along with ancillary data about the key and its owner. The certificate is itself digitally signed by the entity, usually a mutually trusted third party, that issued the certificate. This enables users to verify that the public key is valid and trustworthy.

A digital ID is the private key component of a key pair. Normally the private key is not stored together with the public key, but instead is stored in a separate physical location for security, usually requiring a password to access it. A key manager maintains links between the digital certificate and its associated private key. In many cases, it is convenient to use the term “digital ID” to mean both the public and private keys, even though they are physically separated.

It is almost always a good idea to time stamp digital signatures. Time stamping involves sending the digital signature to a time stamp authority, who then creates and returns a digitally signed time stamp that is uniquely and securely associated with the original digital signature. The time stamp can then be verified by third parties in the future by using exactly the same technique used to verify a digital signature.

I think these important terms deserve a review. A “digital certificate” is a public key, which is itself digitally signed by a mutually trusted third party. Your digital certificate represents your public digital identity, and it should be made freely available to anyone who wants or needs it. A “digital ID” is a digital certificate and the private key associated with the digital certificate. It isn’t difficult to create your own self-signed digital ID, but a digital ID is only as good as the issuing authority that signs it. When you purchase a digital ID from a third party like VeriSign or Thawte, their reputation makes your digital ID more trustworthy.

Digital Signatures: Philosophically Speaking

Mon, 10 Dec 2007 21:11:00 +0000

There is nothing magical about digital signatures. They are simply an electronic mark used to signify a promise and to cement faith in the document or transaction to which that promise is attached. Some day digital signatures will be as commonplace among CAD professionals as the human readable “wet stamp” is today. However it must also be said that, just as CAD did not make architects more creative, digital signature technology will not make engineers more trustworthy.

The technology to use digital signatures has been around for well over 20 years, and a wide variety of software tools exist today that make digital signatures easy to use on almost any platform. So why is the use of digital signatures not more widespread? Primarily because the utopian dream of a paperless world has yet to materialize.

So long as hardcopy on paper is regarded as the authentic “record” version of a document, digital signatures are virtually useless. Even if new buildings are designed completely in CAD, an architect’s digital signature simply won’t mean anything if downstream consumers of the building design require a paper blueprint. The true benefits of a paperless world simply can’t be realized until every link in the chain has joined the digital club. So long as even a single node on the distribution tree requires a human readable method of verifying authenticity, the architect is forced to use a handwritten wet signature on paper blueprints from the very start.

Handwritten signatures can be scanned into an electronic format, but then they lose their putative value because a digital facsimile is so easily reproduced. Therefore only original and unique handwritten wet signatures are trustworthy in a human readable form. Digital signatures do not translate to paper because they are not human readable. Therefore digital signatures only have value for a document in electronic form. This maxim is fundamental to a proper understanding of the emerging digital signature technology: digital data can only be securely signed by computers; and human readable documents can only be securely signed by humans.

I see many people in the CAD industry looking for a hybrid solution to this paper vs. digital dilemma by using a “digitized signature” (i.e. handwritten on paper, then scanned into electronic format) so that printed output contains this digitized signature. This cannot even remotely be considered a digital signature! There is simply no such thing as a secure printed digitized signature. Yes, you can digitally sign a document that has an embedded digitized signature, but once it is printed, that digitized signature is not worth the paper it’s printed on. Not only could that signature be stolen from the document and used maliciously, there is no way to tell from the signature alone whether or not it has already been stolen and used maliciously.

The only hybrid approach that is practical and legally sound is to use digital and wet signatures in parallel. Using an architect as an example, this would mean creating and disseminating two sets of signed documents: the CAD model of a building (perhaps converted into a common 2D format like PDF, DWFx, or XPS) with the architect’s digital signature and paper blueprints with the architect’s individually handwritten wet signature.

A number of companies claim to sell some sort of hybrid solution involving the creation of a secure digitized signature. This is simply capitalism – selling something useless just because there is a market for it. A digitized signature is only secure if it is never used. I’ve heard the rationalization that the digitized signature printed on paper meets a psychological need for people accustomed to seeing one, even if it has no legal value. In my opinion, such pandering borders on deception and serves only to further alienate digital signature technology from those who would benefit from it. This sort of abuse is typified by an emailed PDF file consisting of a scanned document with a handwritten signature. In such cases, checking the sender’s email address likely becomes the most reliable way to verify the document’s trustworthiness. Spam filters bear witness to the fact that the sender’s email address is the most important – and often only – criteria we use in determining the level of trust to place in emailed documents. This is an important point to keep in mind.

The act of applying a digital signature requires the use of a secure private encryption key, but the digital signature alone does not provide security in any way. Digitally signing a document does not prevent it from being modified or stolen. In that respect it is no different than a handwritten wet signature. However, unlike a wet signature that cannot be easily duplicated, a digital signature does not prevent a signed document from being copied. This does not make digital signatures inferior. On the contrary, making copies is necessary and commonplace in the digital world, so the fact that exact copies of digitally signed documents are still trustworthy is a huge benefit over handwritten signatures.

There are other notable differences between a digital signature and a handwritten signature. Digital signatures can be time-stamped, thus providing reliable evidence that a document was signed on or before a certain time. A disadvantage of digital signatures is that they are only as reliable as the digital ID used to create them. To combat this problem, a public clearinghouse of compromised digital IDs must be maintained, and auditing systems must be in place to immediately detect and report suspicious activity. Time stamped digital signatures created before a digital ID is compromised can be easily and certainly distinguished from compromised signatures if properly designed and competently managed infrastructure is in place. This is necessary to ensure that previously existing digital signatures survive a compromising event.

In conclusion, adequate technical solutions and time tested safeguards already exist for successfully using digital signatures in a professional environment, but digital consumers still need to learn how to work within the limitations of the technology. Building an acceptable comfort level with a technology that must by its nature completely replace something as significant and culturally ingrained as the handwritten signature will not be easy or quick, but it is inevitable.

Digital Signatures: Prelude

Mon, 10 Dec 2007 21:07:00 +0000

For many, the word "encryption" has a mysterious quality that invokes images of math virtuosos in secret bunkers working feverishly during wartime to break the enemy's coded communications. My first exposure to encryption came in 1996 when I began working with Paul Kohut on the first version of CADLock software for locking AutoCAD drawing files. After overcoming my initial struggle to understand the terminology and get a handle on the mathematics behind encryption, I realized that it wasn't nearly as mysterious and complicated as it first appeared.

AU 2007 Post Mortem

Mon, 03 Dec 2007 15:12:00 +0000

The Hot List

Carl Bass munching on fast food in the food court, and spotted throughout the week yakking with average folks in the halls.
Staggered classes reduced the lunchtime crush experienced at AU 2006.
More ObjectARX programming classes this year. I’m pushing for creating a new “Developer” track for AU 2008.
The Matt Murphy Head (peace be upon him).
Meeting a lot of familiar faces and a few new ones!

The Cold List

VC Build Hook utility for Visual Studio 2008

Mon, 26 Nov 2007 02:27:00 +0000

The new Visual Studio 2008 has been released, and to celebrate, I’ve updated VC Build Hook. The updated utility allows you to use the new IDE while still building with older versions of the build tools.

Why is this necessary? If you build your AutoCAD 2007/2008 ObjectARX application with the Visual C/C++ 9.0 tools, AutoCAD will display a warning message about an incompatible module when you try to load it. You can use VC Build Hook to target all previous AutoCAD versions from a single Visual Studio 2008 solution (if you have the correct version of Visual C/C++ installed alongside Visual Studio 2008).

In my testing so far, existing Visual Studio 2005 projects build without problems in Visual Studio 2008 when VC Build Hook is installed and the new ‘BuildToolVersion’ property is set to the correct version.

OpenDCL 4.1 Released

Wed, 21 Nov 2007 10:50:00 +0000

OpenDCL 4.1 adds support for the AutoCAD 2008 64-bit platform, includes many improvements in the OpenDCL Studio editor, and has a completely rewritten grid control.

Next on the agenda is adding support for localization so that local language translations can be easily created.

The War On Security

Thu, 01 Nov 2007 13:35:00 +0000

Security and encryption legend Bruce Schneier posted this essay:
The War on the Unexpected

I think we should all be reminded that representative governments are always at risk of death by democracy: suicide under the watchful eyes of a body politic beholden only to the next election.

AutoCAD 2008 Slow Startup Fix

Thu, 06 Sep 2007 15:54:00 +0000

[Update: See Disable AutoCAD InfoCenter]

I’ve noticed more frequent posts in the Autodesk discussion groups about slow startup problems since AutoCAD 2008 was released, and I have the same problem on my development system. Part of the problem is .NET loading, due to the new .NET gadgets like the dashboard palette. Another long running startup hassle is the communication center (WSCommCntr1.exe if you check running processes in task manager) that Autodesk products use to call home.

OpenDCL 4.0 Debuts

Wed, 01 Aug 2007 09:51:00 +0000

OpenDCL 4.0 has finally been released. If you’re not familiar with OpenDCL, check it out at www.opendcl.com, or on SourceForge at sourceforge.net/projects/opendcl.

OpenDCL, based on the original commercial ObjectDCL software by Chad Wanless, is a modern replacement for the old DCL dialog control language in AutoCAD. The current OpenDCL Runtime supports AutoCAD 2002 through 2008 (except AutoCAD 2008 x64). It is designed to give AutoCAD end users and AutoLISP application developers a simple yet powerful way to design and use rich user interfaces in their applications.

The goal for version 4.0 was to get it stable and fix all the bugs, with minimal new feature development. OpenDCL 4.1 will add support for AutoCAD 2008 x64. After that we will start working on localized language versions, and adding new features.

OpenDCL is licensed under the GNU General Public License (GNU GPL) open source license, completely free to use, and source code is available on SourceForge.

What time is it?

Thu, 21 Jun 2007 20:13:00 +0000

AutoCAD 2004 introduced the ability to digitally sign drawing files when they are saved, but very few people use this feature. Even fewer use the time stamp feature that goes along with it. Time stamping a digital signature is important when it’s not only important to know who signed it, but also when they signed it.

For time stamping to be reliable and trustworthy, you need an independent (and trustworthy) third party to provide the time stamp, along with a verifiable receipt so that anyone can verify the authenticity of a claimed time stamp in the event of a future dispute.

Since the inception of the digital signature feature, AutoCAD has included three default time servers for this purpose. Unfortunately, none of the three are accessible any more. If you need to digitally sign drawing files with a time stamp, you’ll have to modify this list of time servers.

The list of time servers is maintained in a file named timesrvr.txt in the AutoCAD installation folder. You can edit the file with notepad, and the format is obvious and straightforward when you view the file.

If you just want to play around with time stamps, try adding the following to the end of the file (you do not need to restart AutoCAD to see the new servers):
NIST A [Maryland] (time-a.nist.gov)
NIST B [Maryland] (time-b.nist.gov)

As of this writing, both of these NIST servers are available and working, but you get what you pay for. For officially incorporating time stamped digital signatures into your workflow, I recommend subscribing to a commercial time service with guaranteed uptime and a web based time stamp verification console. I can’t recommend one, because I have never used a commercial time service myself, but a good place to start is the list of public time servers maintained by NTP.org at http://support.ntp.org/bin/view/Servers/.

Visual Studio Build Configuration Tip

Fri, 15 Jun 2007 12:30:00 +0000

I’ve received several emails recently from users of my VC Build Hook utility that mention switching the ‘UseVC7Paths’ setting on and off depending on the build configuration they are working on. If you are doing this, you need to change your project structure!

DWFx: The Emperor's New Clothes?

Thu, 01 Mar 2007 19:10:00 +0000

I pointed out in a previous post that while the press release headlines pronounced that Vista will support DWF natively, the fine print says otherwise. What Vista does support natively is Microsoft’s new XPS (XML Paper Specification) format. Autodesk has since clarified that they are working on a new DWF format called DWFx that is, essentially, a DWF in XPS format.

A quick test verified my suspicions that XPS files produced by the Microsoft XPS Document Writer are much larger than comparable DWF files. The jury is still out on DWFx file sizes, but a recent post on Scott Sheppard’s blog (http://dwf.blogs.com:80/beyond_the_paper/2007/02/autocad_2008_dw.html) has buried within it a telling comparison point between DWF and DWFx.

The chart uses a neat gambit by comparing both DWF and DWFx file sizes to the completely different DWG format, but the math cognoscenti among you will notice that “typically 1/20 the size of the DWG” for DWF and “typically 1/10 the size of the DWG” for DWFx translates into “DWFx files are twice as large as DWF”. There is no information on file generation times, another metric worth monitoring.

Autodesk has been pretty generous lately, first giving away Design Review, now perhaps gearing up for an exclusive two-for-the-price-of-one deal on DWFx. I haven’t heard too many customers requesting larger file sizes, though.

Introducing OpenDCL for AutoCAD

Wed, 31 Jan 2007 19:44:00 +0000

AutoLISP programmers may remember a product named ObjectDCL, by 3rd Day Software. ObjectDCL was released as open source in the summer of 2006 by developer Chad Wanless due to his inability to continue supporting the software because of “health reasons”. At the time, many users of ObjectDCL hoped that someone would update the code to work in AutoCAD 2007. Programmer David Robison did some work to get AutoCAD 2007 supported, but the project has been languishing, almost to the point of extinction.

After being asked by several ObjectDCL users whether I could help, I decided a few weeks ago to contribute to the community by getting the original C++ code updated to support AutoCAD 2007. As I am wont to do, I’ve ended up re-architecting much of the code in the process.

The results of my work are available now at the new OpenDCL project on SourceForge. The new 4.0 release is still in the alpha testing phase. If you program in AutoLISP and want to create rich user interfaces for your applications, check it out!

I'll take web sites for $200, Alex: Part IV

Wed, 17 Jan 2007 01:38:00 +0000

(continued from Part III)

Creating custom modules for DotNetNuke is an esoteric process that I don't recommend unless you're prepared to invest quite a bit of time and effort. I slogged through the process because I'm too stubborn to quit, but it's hardly worth the investment in time for a one-off custom module. I don't expect many of my readers to try it anyway, so I won't bother describing the technical aspects in any detail.

I'll take web sites for $200, Alex: Part III

Fri, 12 Jan 2007 23:20:00 +0000

(continued from Part II)

DotNetNuke (aka DNN) is not simple to set up. It needs at least the free SQL Server Express Edition on the host system (full SQL Server requires some changes to the default configuration) and either IIS or another ASP .NET 2.0 compatible web server to run on. If you have Visual Studio 2005 fully installed, you have all you need to run DNN.

My ManuSoft manifest manifesto

Thu, 11 Jan 2007 13:10:00 +0000

With the advent of Visual Studio 2005 and automatically generated manifest files, the topic of when and how to use manifest files comes up occasionally. Since a default ObjectARX wizard generated project in Visual Studio 2005 generates an embedded manifest by default, most people don’t even think about it. Of course that was the whole idea – the manifest would ensure that the correct dependent DLLs get loaded, and voila, no need to think about it. One of my programming axioms applies in this case: TANSTAAFL.

The problem is that ObjectARX applications are not in charge. AutoCAD is in charge, and it will decide which VC runtime and MFC runtime DLLs to load. If your ObjectARX application loads a different VC or MFC runtime than the ones AutoCAD is using, you’ll encounter big problems. I’ve always advised disabling the manifest completely (see my ObjectARX Tips page) to avoid such a possibility. Unfortunately, there’s a catch.

The problem is that linking to the ATL80.DLL file isn’t possible by just disabling the manifest and doing nothing more. ATL is now a side-by-side (SxS) assembly, and it no longer lives on the Windows support path, so a standard un-manifested DLL won’t be able to find it. The preferred solution is to link statically to ATL (see Configuration -> General -> ‘Use of ATL’ in VS 2005 project properties) and avoid the problem altogether. If you only have one module that uses ATL, this is always the best solution.

The less desirable solution is to add a manually-created manifest that specifies the desired ATL SxS assembly, but ignores the VC and MFC runtime DLLs. You’ll still need to decide whether to make ATL shared or private, and in either case you must distribute ATL with your application to ensure that it is available when your application is deployed. You can cheat, and let VS generate your manifest file (instruct it to not embed the file), then just edit the resulting .manifest file to remove references to the VC and MFC assemblies. For example, here’s one that I generated (you’ll need to generate your own to ensure that the manifest matches the version you are redistributing):

<?xml version=“1.0” encoding=“UTF-8” standalone=“yes”?>
<assembly xmlns=“urn:schemas-microsoft-com:asm.v1” manifestversion=“1.0”>
<dependency>
<dependentassembly>
<assemblyidentity type=“win32” name=“Microsoft.VC80.ATL” version=“8.0.50727.762” processorarchitecture=“x86” publickeytoken=“1fc8b3b9a1e18e3b”>
</assemblyidentity>
</dependentassembly>
</dependency>
</assembly>

In my work, I’ve had very little need for manifests. The VC optimizer is able to strip the unused portions of statically linked ATL out of your code, leaving a much smaller footprint than the entire assembly would require. This eliminates the need to redistribute ATL with your application, thus reducing the overall potential for deployment issues. Nevertheless, there are exceptions to every rule, and your mileage may vary.

I'll take web sites for $200, Alex: Part II

Thu, 11 Jan 2007 01:41:00 +0000

(continued from Part I)

The kind of web site I wanted to create is usually built on top of a Content Management System (CMS) that becomes the administrative user interface as well as the framework for web pages that get served to web site visitors. The first thing I learned is that there are thousands of CMS products floating about the internet, from simple “guest book” type scripts to full blown corporate extranet management systems designed for use by tens of thousands of employees and customers. I’ve also been looking for an excuse to learn ASP.NET, so I decided to narrow my search to CMS software that was based on ASP.NET. Finally, the software had to be free or very inexpensive.

I'll take web sites for $200, Alex: Part I

Mon, 08 Jan 2007 17:35:00 +0000

I’m one of those throwbacks that learned HTML by typing it in Notepad. I’ve since moved up to using the Visual Studio editor; it does syntax coloring, error highlighting, and has a “design” mode for previewing the page, yet it’s a very utilitarian editor that I feel comfortable with. I do use FrontPage when I need to manage connections between multiple HTML pages, but mostly in raw HTML mode. When I use WYSIWYG design mode in FrontPage, I inevitably end up cleaning out a lot of unnecessary junk that it includes in the generated HTML. I think it’s fair to say that my obsession with clean HTML results in utilitarian, functional, and standards conformant presentations – but with a decided lack of graphic appeal.

The ManuSoft and CADLock web sites are examples of this utilitarian approach. The ManuSoft site uses no fancy graphics and relies very little on client side scripting, and it supports a hierarchical navigation system using only standard hyperlinks. I like that minimalist approach, but the price for clean HTML being served to clients is a lot of work on the server to maintain the site. As a result, I don’t update the site very often because it’s just too difficult.

This blog was the first step toward realizing a goal of making it easier to add new content. After all, the raison d’être of blogs is to minimize the latency between the writer’s stream of consciousness and words on the web by making it irresistibly easy to add new content. This is precisely why blogs have become so popular.

Unfortunately, I soon found limitations with my blog. Tabular lists of data still require manual HTML input, it is difficult to customize the content area outside the individual posts on the blog page, and most aspects of the hosted blog software are outside my control. I wanted more.

The Autodesk vs. Open Design Alliance lawsuit gave me an excuse to take the next step: implement the “blog” concept across an entire web site with software that I control. So, I decided to swallow my pride and learn how to create an entire web site that would be so easy to update that I would actually update it frequently – even if it meant messy HTML code. Stay tuned for Part II, choosing a hosting service and deciding which software to use.

VCBuildHook updated for VS 2005 SP1

Tue, 19 Dec 2006 17:13:00 +0000

I’ve installed Visual Studio 2005 SP1 and have been busy testing all my projects to make sure they didn’t break. Microsoft did fix at least one of the bugs I reported (the resource editor choked on resource strings that contained an embedded NULL character), but the IDE still crashes fairly consistently if I initiate a large solution build while the Intellisense database is being rebuilt. SP1 also managed to break my VCBuildHook utility, so I’ve uploaded an updated version (2.0.3.0) for use with SP1.

Visual Studio Version Hunt

Fri, 08 Dec 2006 20:06:00 +0000

If you’ve been programming with ObjectARX for a while, you already know that each version of the ObjectARX SDK only works with a specific version of Visual Studio. Mazhar Basa touches on the subject in his article Components of ObjectARX Applications. My VCBuildHook utility makes it possible to build for multiple target AutoCAD versions from a single Visual Studio 2005 solution, but this utility still needs the older versions of Visual Studio to be installed on the same system in order to perform its magic.

The problem is, legitimate licenses of older versions of Visual Studio are hard to come by. Back in the Visual Studio .NET 2003 days, you could purchase a new license of VS 2003, then get a free license downgrade from Microsoft that allowed you to install Visual Studio 2002 side by side on the same system. That combination allowed you to target AutoCAD versions as far back as AutoCAD 2004. Unfortunately, Microsoft stopped offering the VS 2002 downgrade license when Visual Studio 2005 began shipping in November of 2006.

The end result is that new ObjectARX programmers are faced with a dilemma if they need to target anything older than AutoCAD 2007. One of the attendees at my “High-Octane ObjectARX” class at AU 2006 reminded me that MSDN (Microsoft Developer Network) members can download older versions of Visual Studio from the MSDN subscriber download center.

I have verified that Visual Studio .NET 2002 (VS 2002) is available for download to MSDN Professional subscribers, but I could not find Visual Studio 6.0, which is required to target AutoCAD 2000 - 2002. Visual Studio 4.2 (required for AutoCAD R14) is available though, so maybe I’m just not looking in the right place.

If you are a professional software developer, whether commercial or in-house, you should consider subscribing to MSDN for various reasons. If you’re an ObjectARX programmer and need to target older versions of AutoCAD, MSDN may be the only way to obtain the older Visual Studio build tools and libraries that you’ll need.

Does Vista really open DWF files?

Tue, 05 Dec 2006 05:12:00 +0000

Not according to the press release. Vista (and .NET 3.0) includes a built-in XPS Viewer (also available for Windows XP SP2 and Windows Server 2003), which will view any XPS format file. Apparently Autodesk plans to add support for output to XPS format in the future, and this output will be called DWFx – a new file format. It’s not clear what the difference will be between DWFx and the output produced using the Microsoft XPS Document Writer that is already available.

I installed the Microsoft XPS Document Writer and XPS Viewer on my Windows XP SP2 machine. Next, I started AutoCAD 2007 and opened “3D House.dwg” from the Sample folder. I then plotted this file to DWF, PDF, and XPS, with the following results:

Plotter	Plot Time	File Size
DWF6 ePlot.pc3	7 seconds	139 kb
DWG To PDF.pc3	5 seconds	165 kb
Microsoft XPS Document Writer	34 seconds	829 kb

I’m not suggesting that these files all contain the same content, I’m merely suggesting that DWFx/XPS may have some undesirable tradeoffs in practice.

This whole issue about “native Vista support for DWF” may be nothing but smoke and mirrors. There is no guarantee that publishing CAD data in the XPS format will be efficient. So what will happen if users can choose between a compact DWF, a slightly less compact but ubiquitous PDF, or a very space-hungry DWFx? Time will tell, but I think this issue of DWF in Vista is getting way to much spin and not enough critical analysis.

Demand Loading a VLX File

Mon, 04 Dec 2006 18:34:00 +0000

Some years ago I wrote a small ObjectARX module named VLXLoad that loads a .vlx file of the same name and in the same directory as the .arx module. I never claimed credit for the utility, but now that I’ve released the source code, I guess I’ll have to own up to it.