Through the Interface

Maintaining per-object XData in AutoCAD using .NET

As a follow-on from this recent post, I decided to take a stab at a more generic solution for managing XData that should remain unique – i.e. attached to a single object – inside an AutoCAD drawing. This was prompted by an internal discussion that included a long-time colleague, Randy Kintzley, who suggested the approach taken in this post. (Thanks also to Tekno Tandean and Davis Augustine for adding valuable comments/feedback.) Randy’s suggestion was to avoid per-command event handling completely by adding an additional piece of XData – the handle – to objects that need to be managed in... Read more →

Filtering lists of AutoCAD entities using LINQ

A comment on the last post made me think it’s probably worth diving into LINQ a bit further, as there’s clearly interest out there. Now I don’t actually use LINQ very much but whenever I do I tell myself I ought to use it more – it’s really very useful. A lot of LINQ is derived from the world of Functional Programming – in that it allows you to use higher order functions to manipulate data – and it’s really just another way in which .NET languages have been influenced by FP (and have evolved to incorporate its techniques... Read more →

Performing Boolean operations on AutoCAD solids using .NET

I looked back and couldn’t find a post covering this particular topic and so decided to put something together. It may well have been covered elsewhere (I admit to not having looked) but I felt like throwing some code together, either way. :-) To perform a Boolean operation between Solid3d objects inside AutoCAD, you can use Solid3d.BooleanOperation() on the primary Solid3d, passing in the secondary one. We want to implement commands for Unite (or Union), Intersect (Intersection) and Subtract (Subtraction). Only the last of these needs us to select a primary object explicitly – as the other two operations... Read more →

A framework for defining AutoCAD entity jigs using .NET

In the last post we saw some code to create a frustum-shaped Solid3d object inside AutoCAD. I mentioned at the bottom of that post that there seemed to be an opportunity to write a framework of some kind to abstract away some of the repetitive code needed to create a multi-input jig. I probably didn’t say it in quite that way, but that was what I was getting at. :-) Anyway, after having looked at it some more, here’s what I came up with: the EntityJigFramework. It’s a class derived from EntityJig that encapsulates some of the common code... Read more →

Creating a selection filter that finds dynamic blocks in AutoCAD using .NET

An interesting question came in via email from Rob Outman. He’s interested in applying a selection filter when the user selects dynamic blocks. This is straightforward for unmodified dynamic blocks – just as with standard blocks, you can filter on the block name very easily – but it works less well on dynamic blocks whose properties have been modified at an instance level. Essentially what happens is this: if you select a block reference to a dynamic block in the AutoCAD editor and then use (for example) the Properties window to edit some of the custom properties associated with... Read more →

Creating reactive, transient AutoCAD geometry using .NET

This is a really interesting topic. At least I think it is – hopefully at least some of you will agree. :-) The requirement was to create selectable – or at least manipulatable – transient graphics inside AutoCAD’s drawing canvas. As many of you are probably aware, transient graphics are not hooked into AutoCAD’s selection mechanism. This is mostly fine, but if you want to implement a ViewCube-like gizmo that manipulates the view or drawing settings in some way, it’s hard to do so without the ability to react to the current cursor position is and what’s happening with... Read more →

Creating 3D street art using AutoCAD

As mentioned in this previous post, I was very keen to see how AutoCAD could be used to help streamline the process of generating what I’ve now found out can be classified as anamorphic street art. Leon Keer had mentioned that the technique dates back to Leonardo Da Vinci and – sure enough – Wikipedia agrees. As part of my research, I found the original video that inspired my interest in Leon’s work, which should help put this post in context: To make the process reasonably realistic – and to some degree replicate the approach Leon has taken in... Read more →

Chamfering the selected edge of an AutoCAD solid using .NET

Another piece of code culled from an email from Balaji Ramamoorthy, from DevTech India. I did a little refactoring and formatting, to fit the blog. Thanks, Balaji! :-) The below C# code demonstrates how to use Solid3d.ChamferEdges() with a user-selected edge and face. Balaji has also provided code to determine the edge and face programmatically – without the user needing to select anything – using the Brep API. I expect to show that approach in a subsequent post. using Autodesk.AutoCAD.ApplicationServices; using Autodesk.AutoCAD.DatabaseServices; using Autodesk.AutoCAD.EditorInput; using Autodesk.AutoCAD.Runtime; using System; namespace SolidEditing { public class Commands { [CommandMethod("EC")] public void EdgeChamfer()... Read more →

Creating a legend of AutoCAD drawings using .NET

This interesting question came up in our discussion forums: Does anyone have a routine that will insert all the drawings from a single folder into one drawing to create a legend sheet? I'm trying to document the company's various blocks and details for dissemination amongst several offices. The simplest – and most elegant, in my opinion – approach for addressing this requirement is via the Table object, which allows you to include block thumbnails in each of its cells. So we would need to import the various drawings into the current drawing as blocks, and then point the various... Read more →

Displaying an AutoCAD ribbon tab contextually using .NET

This very interesting feature came to my attention via an internal discussion. Thanks, once again, to George Varghese for providing the base sample used for this post. At various times inside AutoCAD – such as when a block is selected, for instance – a specific ribbon tab is displayed “contextually”. As an example, when you select a Hatch object inside the AutoCAD editor, you should see a hatch-related contextual tab displayed: It’s possible to implement your own, comparable behaviour inside the AutoCAD editor using a combination of a simple .NET module, a XAML file and some CUI editing (or... Read more →

Preventing AutoCAD objects from being selected using .NET

In the last post, we looked at how to stop entities from being highlighted during selection. This post looks at how to stop entities from being selected at all. Thanks again to Balaji Ramamoorthy for providing the underlying technique shown in today’s code. The basic scenario we’re using is similar to the last post – we maintain a list of DXF names for the classes we want to stop from being selected – but it could easily be adapted to using different criteria for removing objects from the selection: an example being the use of a similar (although admittedly... Read more →

Preventing AutoCAD objects from being highlighted using .NET

Thanks to Balaji Ramamoorthy, from DevTech India, for the basis of this post (some code he provided in a recent reply to an ADN member). The original question came from someone who wanted to stop text objects from being highlighted when selected. I’ve extended the mechanism to make it a little more flexible: it now maintains a list of object types (their DXF names) of objects that should not be highlighted, when selected. Balaji implemented a HighlightOverrule to control the highlighting. This doesn’t stop the objects from actually being selected, however: in the next post I’ll add some additional... Read more →

AutoCAD .NET Training DevTV Session 2: User Interaction – User Input

It’s Friday, which means it’s time for the next installment of Wayne Brill’s AutoCAD .NET training DevTV series (as mentioned in last Friday’s post). Today’s session is focused on user interaction and user input. This series of DevTV sessions is a companion for the new AutoCAD .NET training material available from the AutoCAD .NET Developer Center. Enjoy! :-) Read more →

Returning an average point to the AutoCAD command-line using .NET

This request came in over the weekend: There is a useful object snap in AutoCAD for the mid point of 2 selected points. I would like a midpoint (average) of 3 (or more) points. Could this work in 3D as well as 2D? It’s useful when drawing building surveys, often you triangulate a point from several and there are often ‘minimal’ differences in the dimension and you just take the average. Given the fact we’re actually talking about an arbitrary number of points that will almost certainly not belong to a single entity, object snaps are probably neither the... Read more →

A tool to help understand transformation matrices in AutoCAD

As promised, today’s post delivers a simple application that provides a user-interface for the command implemented in this previous post. I chose to implement the UI as a WPF user control which is then hosted by a standard AutoCAD palette. Aside from its core function – to allow composition of transformation matrices to be applied on an AutoCAD object – it demonstrates a couple of handy tips for working with Palettes: Separate the core functionality from our UI, using SendStringToExecute() to call it This will reduce the chance of issues related to Document vs. Session context, document-locking, etc. If... Read more →

Adding a 2D spatial filter to perform a simple xclip on an external reference in AutoCAD using .NET

I’ve now checked in for my flight to Las Vegas – and, thanks to Jeremy Tammik’s recent troubles, I luckily renewed my ESTA – so I’m pretty much all set for my trip to AU 2010, at least from a travel perspective. I’m just keeping my fingers crossed that the gastric 'flu my kids seem to have come down with doesn’t hit me before I leave (or once I’m at AU… what a grim thought). I was going to keep today’s post light, just like the last one, but then decided to dip into my email folder of externally... Read more →

Generating C# code for selected AutoCAD polylines using .NET

Here’s an idea I’ve been playing around with for some time: say you want to capture geometry as code for pasting back into your application, how do you do it? For instance, sometimes you might want to model geometry using AutoCAD and then capture it as code for later generation at runtime. I have a specific example in mind, of course: I have some boundary loops that can be used to generate the outer shell of a space shuttle using the surfacing capabilities introduced in AutoCAD 2010. I’d really like to use code to store these loops and –... Read more →

Jigging an upright, square, AutoCAD raster image using .NET

Following on from these two posts, we’re now going to implement a jig to create our QR Code raster images inside AutoCAD. Today’s approach isn’t radically different from the previous one prompting selection of corners, but we do get to see the actual (square) boundary of the raster object as it gets defined. It would have been even better if the raster contents were displayed during the jig, but from what I can tell this has been disabled deliberately, no doubt for performance reasons (you see the same effect – only having the boundary visible – when you move... Read more →

Attaching an “upright” raster image at a user-specified location in an AutoCAD drawing using .NET

As promised, the code in this post extends that from the last post to add some user selection to the process of defining and placing a QR Code in an AutoCAD drawing. This version of the code also makes sure the raster is positioned in an “upright” orientation, irrespective of the order in which the corners are selected. Many images need to be positioned in such a way (although QR Codes are presumably more tolerant due to the positioning squares in three of the corners), so I expect this technique will be of interest to various people who need... Read more →

Changing the layer or color of a nested entity using .NET (take 2)

A big thanks to Thorsten Meinecke for pointing out the obvious issue with my prior post (the nested entity selection loop which has frustrated me unnecessarily when developing the code for that post and another). Here are the details of the fix: using Editor.GetNestedEntity() along with a PromptNestedEntityOptions object, instead of a direct message string, allows us to specify AllowNone to be true. Which, in turn, causes PromptStatus.None to be returned when the enter or space keys are used to terminate the selection loop. An obvious omission, in hindsight, but anyway – I’m much obliged to you, Thorsten! :-)... Read more →