Through the Interface

Merging AutoCAD blocks using .NET

I decided to dust off Visual Studio and write a quick AutoCAD app, this morning. It tackles a question received via a blog comment from Pankaj Potdar, over the weekend. I have two blocks with different attributes I want to merge them in single block, and I don't want to create any nested blocks. I haven’t had much time to spend on AutoCAD, of late. Part of the reason has been work-related: I’m heads-down getting the VR/AR track in shape for the upcoming Forge DevCon, as well as spending time on new duties in Autodesk Research. The other part... Read more →

Unlocking layers for certain AutoCAD commands using .NET

This question came up during last week’s accelerator, and is part of the reason I spent creating the last post: is it possible to selectively unlock certain layers for the duration of commands that have been specified by the user? Let’s take an example: you have layers that should remain locked, apart from when using the MOVE command (COPY and ERASE should not work). The approach I took was to maintain a dictionary mapping command names to lists of layers to unlock. When a command is launched – which we can tell using the Document.CommandWillStart event – we check... Read more →

Locking and unlocking AutoCAD layers visibly using .NET

On Friday I visited Munich Airport: not only to catch a flight home to Switzerland but also to take a look at some AutoCAD issues frustrating the developers working on the airport’s facilities management system. During the course of the day we were able to work through a number of problems – such as using COM (SendCommand()) to run a script synchronously as well as to get the fill pattern for MPolygon objects (this is apparently broken in .NET) – but there was one I had to bring home with me: when locking and unlocking layers programmatically, their geometry... Read more →

Creating AutoCAD Xrefs as overlays with relative paths using .NET

After showing how to automatically attach xrefs at the origin inside AutoCAD, and then redoing the approach to take care of different unit systems, I then had the request from a couple of places to look at making the xrefs overlays and adjusting their paths to be relative rather than absolute. Looking around, I found some code on the AutoCAD DevBlog that changes an attachment to an overlay, after the fact. Henrik Ericson found the code didn’t work for him, but did spot the db.OverlayXref() method which did. So I went ahead and made use of that for overlays.... Read more →

Converting units between different AutoCAD drawings using .NET

This is actually a redo of last week’s post, just with a different title: while the approach shown worked well when creating external references to drawings using the same units, when bringing in (for instance) metric xrefs into an imperial master drawing the scale was all messed up. Thanks to Hans Lammerts for reporting the issue. The scaling ended up being straightforward to implement: the hard work was done by UnitsConverter.GetConversionFactor(), which established the scale factor to use, converting between the Units property of the new block table record and the Insunits property of the target database. Then it... Read more →

Creating an AutoCAD layout with custom plot and viewport settings using .NET

This request from Thomas Longnecker languished in my inbox for several weeks before I finally found the time to work on it. It would be tremendously helpful to me if you could give an explanatory example of how to: Create a new layout, add a page-setup with plot-settings and then either delete the default viewport and create a new one or possible change the default viewport. […] Within the newly created layouts I needed to set some of the general Plot setting, mainly Paper size and Plot style table. Some of the main things for the viewport was to... Read more →

Attaching AutoCAD Xrefs and inserting them at the origin using .NET

I just received this interesting (and quick to solve) question from Henrik Ericson, this morning: I’m looking for a new xref command (or perhaps overriding the internal xref command) that always insert the selected xref at 0,0,0 coordinates and in World coordinate system. I’m often inserting an xref and ’nothing happens’ and then I realize that I’m in a UCS. I created a simple command called XAO – for XrefAttach[At]Origin – that does just this. As a helper function I implemented a simple extension method to both attach and insert an external reference in the current space of the... Read more →

Applying an operation to all the entities in an AutoCAD drawing using .NET

In the last post we saw a “general” function to erase all the entities in a drawing that fulfill a specified condition. We used it to erase all the zero-length lines in a drawing. But as I’d mentioned at the end, I thought there was an opportunity to generalize the mechanism even further. Here’s what I came up with (and I’ve included a suggestion by Parrish Husband to create an additional extension method for Curve.IsZeroLength()). using Autodesk.AutoCAD.ApplicationServices; using Autodesk.AutoCAD.DatabaseServices; using Autodesk.AutoCAD.Geometry; using Autodesk.AutoCAD.Runtime; using System; namespace ZeroLengthEntities { public static class Extensions { ///

/// Performs an operation... Read more →

Adjusting the size of multiple AutoCAD text and block attribute objects to fit their containers using .NET

This is a follow-up to the post where we modified the size of selected text in a drawing, to make it fit its container. I received this comment last week: instead of selecting the nested entities one by one, is it possible to make a "selectall" selection ? It turns out that the question was related to a completely different post, but by the time I realised I’d already completed most of the work. It seems a very valid question for this topic, so that’s fine. :-) Looping through all the text – some of which may be nested... Read more →

Preventing AutoCAD objects from being purged using .NET – Part 2

In the last post we introduced a static C# class containing extension methods for the ObjectId and Transaction classes. The new Transaction methods allow you to more easily “lock” objects, whether because they’re “system” objects you want to keep around in every drawing or because they’re objects that shouldn’t be purged at whim by users. Under the hood, the implementation uses Xrecords stored in the Named Objects Dictionary that contain hard-pointer references to the various locked objects. This stops the PURGE command from removing them, but also allows us to check via Database.Purge() – or our new ObjectId.IsErasable() shortcut... Read more →

Preventing AutoCAD objects from being purged using .NET – Part 1

This is one of those topics that has been at the back of my mind for a number of years. Here’s a question I received via a blog comment back in 2009: I was wondering if there's an easy way to modify the objects to purge. For example, if a particular text style was included in the drawing that I did not want to be purged. Can this easily be done? Here’s how I responded, at the time: There are a couple of ways: You can maintain your own list of objects "to keep" and remove any items that... Read more →

Checking for built-in AutoCAD objects using .NET

This interesting question came in by email from Igor, over the weekend: Let say I want to delete a layer by it's name. I can get ObjectId or LayerTabelRecord from the name, like LayerTable tLayers = (LayerTable) Transaction.GetObject(Database.LayerTableId,OpenMode.ForRead,false) LayerTableRecord ltRecord = (LayerTableRecord) Transaction.GetObject(tLayers.Item[Name],OpenMode.ForWrite,false); Now having LayerTableRecord how can I found out that this DBObject is not the built-in one? Like names '0' or 'DEFPOINTS'. Same goes for TextStyle (STANDARD) or layout (MODEL)….? I can't found any property regarding this, like IsBuiltIn. The IsPersistent property is no help. It’s true that there isn’t an IsBuiltIn property on AutoCAD objects… for... Read more →

Replacing AutoCAD blocks with Xrefs using .NET

I mentioned in a recent post about some code I put together to replace a drawing’s internal block structure with external references. The code determines the blocks used in the modelspace and then works through, saving each to a file via the wblock mechanism and then attaching them back in as Xrefs. The code was surprisingly easy to put together. It’s a bit on the destructive side – it rips out blocks and creates equivalent drawings in the temp folder – so I do suggest running this on a copy of your drawings. But as part of a process... Read more →

Preventing an AutoCAD block from being exploded using .NET (redux)

When I was a boy, I used to love going to play with toys at my grandmother’s house. My absolute favourite was a die-cast Batmobile made by Corgi in the UK. What I particularly liked about this toy was its hidden features: the cars apparently came with secret instructions, although these were nowhere to be seen by the time I started playing with it. The Batmobile had plastic flames that came out of the exhaust when the rear wheels turned and spring-loadable, vertical rocket launchers. The biggest surprise was when I discovered the cutting blade that popped out of... Read more →

Puzzling over laser cutters

After introducing a rudimentary program to help build jigsaw puzzles, we needed to fabricate the design in some way. As mentioned originally, we quickly discarded the idea to 3D print it as too time-consuming and unreliable: we decided to at least investigate using a laser cutter, what I considered to be a more natural choice for this. Now I did have some experience of using the laser cutter at our local Fab Lab, but as we wanted to iterate quickly – and didn’t have the fixed requirement of the larger cutting bed – we opted to use a slightly... Read more →

Modifying the contents of an AutoCAD xref using .NET

An interesting query came into my inbox, last week. A member of one of our internal product teams was looking to programmatically modify the contents of an external reference file. She was using the code in this helpful DevBlog post, but was running into issues. She was using WblockCloneObjects() to copy a block definition across from a separate drawing into a particular xref, but found some strange behaviour. In this post I’m going to show the steps we ended up following to make this work. We’re going to implement a slightly different scenario, where we modify an external reference... Read more →

Selecting a linetype and applying it to a set of AutoCAD entities using .NET

I received this request from Mateusz Andrzejczak, over the weekend: I have problem with LineTypeDialog. Your part of the code is working perfectly, but i have problem with modifying the values. I have a SelectionSet that holds all object that are selected with using a filter. I want to use LineTypeDialog to select linetype and then accept so all the object in selection set will change to selected linetype. I'm working with this for a few hours and it's not working. Any tip for me? The question related to this old post. I started by sending Mateusz a link... Read more →

Recreating the Star Wars opening crawl in AutoCAD using F# – Part 4

Happy Friday! It’s time to unveil the completed Star Wars opening crawl inside AutoCAD… After an intro and seeing various pieces implemented, in today’s post we’re going to add the crawl text and animate its movement into the distance. The initial blue text The theme music The star field The disappearing Star Wars logo The crawling text As the surprise “bonus” item 6, I decided to add a planet and – at the end of the crawl – shift the view downwards to show its surface: an effect I’ve seen in the opening crawl for at least one of... Read more →

Recreating the Star Wars opening crawl in AutoCAD using F# – Part 3

Now that we’ve introduced the series and seen how to add some introductory text, theme music and a field of stars, it’s time for the Star Wars logo. The initial blue text The theme music The star field The disappearing Star Wars logo The crawling text The logo came, once again, from the HTML opening crawl, which embeds some SVG content representing it. I copied this into a standalone SVG text file, ran it through a web-service to translate it to DXF and then opened that inside AutoCAD. The outlines of the letters (or groups of letters) were continuous... Read more →

Recreating the Star Wars opening crawl in AutoCAD using F# – Part 2

After introducing this series in the last post, today we’re going to address the first 3 items on our TODO list: The initial blue text The theme music The star field The disappearing Star Wars logo The crawling text The following two items are fairly significant, in their own right, so they’ll each take a post of their own to complete. Oh, and I’ve thrown in a surprise item 6, which I’ll unveil when we implement the crawling text. Before we dive in, it’s important to make some points about the code: because this is mainly just a bit... Read more →