LT Unlimited

Breakline Dynamic Block -- Part 3

Today's post continues the creation process for a breakline dynamic block. Here's where we left off last time, with independent stretch actions on the left and right ends of the breakline:

The last thing I want to do is add a rotation action. Sure, you could use the regular rotate command, or grip-edit the block, but having an action to rotate the breakline seems faster to me, since you've already got the block selected to change its end points. If you don't want to rotate your breakline with an action, you certainly don't have to.

As usual, I'll start by adding the rotation parameter. I'll pick the center, the radius, and the default rotation angle. Since our breakline starts out horizontal, that default angle is 0. Non-zero default angles come in handy when your default state is not horizontal. Then, any rotation can be done incrementally, instead of having to do the math back to zero. Anyway, here's what it looks like:

For a rotation parameter, the grip location is fairly arbitrary. Just put it somewhere where it'll be obvious what it affects. And there's that exclamation point again -- I'll double click on it to create the rotate action.

After double-clicking, the first prompt is to select objects. That's because, unlike linear parameters, rotation parameters can have only one action type. So there's no need to prompt you with a choice.

I select the polyline and the two distance parameters (so that the stretch grips rotate with the line), and I'm done.

Now I have a dynamic block with 3 possible actions -- stretch the left end, stretch the right end, and rotate.

On Monday, I'll post a video showing the creation process start-to-finish.

Breakline Dynamic Block -- Part 2

In the last post, I started the process of creating a dynamic block breakline, beginning with stretching the right end of the line. Here's where we left off:

Now let's go get the other side.

I prefer to have the left and right sides of the breakline stretch independently. Sometimes, things just aren't symmetrical. So to stretch the left side, I'll just repeat the process from last time.

1. Create a linear parameter from the center of the breakline to the left end.
2. Double-click the exclamation point and choose Stretch.
3. Select the left-hand grip as the associated parameter point.
4. Draw the stretch window around the left end of the breakline.
5. Select the polyline as the object to stretch.
6. Select the parameter and use the Properties palette to set the number of grips to 1.

And here's what I get:

If you like shortcuts (and who doesn't?), there's a "Linear Stretch" item on the "Parameter Sets" tab of the Block Authoring Palette. It does steps 2, 3, and 6 for you.

Maybe in your world, though, your breaklines are always symmetrical. In that case, there's no need for a second parameter. Here are two ways you can create symmetric stretching with one parameter and two actions.

1. Use a stretch action on the Distance 1 parameter with either a distance multiplier of -1 or an angle offset of 180 degrees.

This method uses the same parameter and associated point as the first stretch action, but the stretch window is on the other end.

The other difference is in the action's properties. When the right end moves right, the left end needs to move left (and vice versa). To make this happen, you can either give the action a distance multiple of -1, or an angle offset of 180 degrees. It doesn't matter which one you use.

Now we have a block with one grip that moves both ends.

2. Adjust the Distance1 parameter to have 2 grips and a base location of "midpoint", and use the action from method 1.

Until now, we've been stretching linear parameters from what's called the "startpoint", or the first defined point of the parameter. But you can also have linear parameters that stretch symmetrically from their midpoint.

First, I'll adjust the location and properties of the Distance1 parameter.


Notice that the exclamation point is back, and that the blue "x" is still in the center of the polyline. (Before, it was attached to one end of the Distance1 parameter.)

Next, I'll create the stretch action for the left side of the breakline, making sure that the "associated point" is the left end of the parameter.

I don't have to do anything special to the action -- it automatically moves the correct way.

In this configuration, moving either grip also adjusts the other side, so that the breakline once again stays symmetric.

In the next post, I'll show you how to add the optional rotation action and parameter.

Breakline Dynamic Block -- Part 1

Last week, I posted about a dynamic block breakline that I'd created to mimic the behavior of the Express Tool.

This week, I'll go through the steps to create it, showing you a few dynamic block tips and tricks along the way.

Step 1 is to create your geometry. I just drew a polyline in the shape of my default breakline.

Step 2 is to create a parameter. A parameter is essentially a type of property -- you can have parameters that define lengths, angles, positions, etc. The first parameter I'm going to create is a linear parameter. It simply defines the distance between two points.

So "Distance1" is now the distance between the center of the breakline and one end. (Notice that I held the end of the parameter back from the end a little. This lets the breakline hang over the edge without having to measure it each time.)

The exclamation point means that the parameter's not done -- it needs an action. Actions control changes in parameters.

Double-clicking on the exclamation point brings up the actions to choose from. For a linear parameter, you can choose Array, Move, Scale, or Stretch. Today, I want Stretch.

Next, I have to pick the parameter point to associate with this action. In other words, should moving the right-hand arrow change the geometry, or should the left-hand arrow? Stretching from the center wouldn't make much sense, so we'll use the right-hand arrow.

Next, I'm asked for a stretch frame. I need to window around the objects and points I want to stretch -- in this case, the right end of the breakline.

Unlike with the regular stretch command, though, drawing the window doesn't mean you're done. In the Block Editor, you still need to select the objects to stretch. This is nice, because it gives you more control over the objects in your dynamic block.

Once I select the polyline, the Action appears next to the parameter. The exclamation point doesn't go away, though, because there's still a parameter grip that doesn't have an action.

If you're on an earlier version of AutoCAD LT, your action will look like this instead:

I don't actually want to use that other grip, so I'll select the parameter and use the Properties palette to set the number of grips to 1.

Testing the block shows me that my stretch action is working as intended. Tune in next time for options for stretching the other end of the breakline.

When this is done, I'll post a video showing the creation process start-to-finish.

Missing dialog boxes

Another popular discussion group question is, "What happened to my dialog boxes?" Someone goes to open a drawing, or save the current one, and instead of the usual window all they see is:

Enter name of drawing to open <.>:
or
Save drawing as <C:\My Documents\Drawing1.dwg>:

What this means is that FILEDIA (short for File Dialog) has been turned off, or set to 0. Macros, scripts, and other routines sometimes do this because having a dialog pop up would interfere with the smooth running of the routine. If the macro etc. doesn't set the variable back, or gets canceled mid-run, FILEDIA can sometimes get left at 0.

To get your browsing-friendly dialog boxes back, just set FILEDIA to 1 again.

<update> Darren Young just reminded me that you can use a tilde (~) to launch the dialog even if FILEDIA is set to 0. That way you can finish your command and then reset the variable, instead of having to start over. Thanks, Darren!

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Comparing AutoCAD and AutoCAD LT

One of the most frequently-asked questions about AutoCAD LT has to be, "What does AutoCAD have that LT doesn't?" The second most-popular question is probably, "What's new in this version of AutoCAD LT?"

To help answer those questions, every year we put out a comparison matrix for AutoCAD vs. AutoCAD LT and another one comparing the latest versions of AutoCAD LT with each other. You can find the latest PDF files here:

AutoCAD vs. AutoCAD LT Comparison Matrix
AutoCAD LT Release Comparison Matrix

Breaklines

I got an e-mail last week asking me about creating break lines in AutoCAD LT. You know, for when you want to show only part of an object and indicate that it continues.

There's no built-in way to do this in AutoCAD LT (AutoCAD has an Express Tool), but it's not hard to make your own.

Here's the dynamic block I built to replace the Express Tool:

Its insertion point is in the center, and it has an independent stretch action for each end. (I use the M2P object snap a lot when placing this breakline. I also threw in a rotation action, but as it acts on the whole block, it's optional. (Without the rotate action, you can accomplish the same thing with grip-rotating or the Rotate command.)

I put the block on a tool palette, and set up its auxiliary scale so that it would insert at the current dimension size. It's worked great ever since.

In the spirit of "teaching to fish", I'm not going to post the block here. It's pretty simple to make -- with just a little knowledge of dynamic blocks you'll be able to create it yourself. But maybe I'll use the rest of this week to walk through the steps...we'll see what other tips I come up with between now and then. :-)

Another Text Editing Shortcut

Last month, I ran a couple posts with keyboard shortcuts for editing text in AutoCAD LT (and other programs).

This week, I got another tip in my e-mail regarding mouse-based editing instead. It's another feature I use all the time, especially when writing blog posts, but it hadn't occurred to me to make it a tip. (Thanks, Murray.)

If you want to move some letters or words from one place in the text object to another, simply highlight them, left-click (holding the button down), and drag-and-drop it to the new location.

Like many of the earlier keyboard shortcuts, this mouse trick works in all kinds of text-editing programs -- AutoCAD LT, Notepad, Word, even fields in web browsers.

And if you're using the old Attribute Editor, you can even drag-and-drop values between attribute fields, as I posted about a while ago. (It doesn't work in the Enhanced Attribute Editor in LT 2010, but that editor has other advantages. And of course there's always cut-and-paste.)

If you have a favorite tip, trick, or hidden feature you'd like to share, send it on in! I'm always interested in how other people are getting the most out of AutoCAD LT.

Purge Empty Objects (the pre-2010 version)

So after yesterday's post on purging zero-length geometry and empty text objects, I was rightly taken to task for hinting that Quick Select can be used to accomplish the same thing and then not telling you how.

Mea culpa -- here you go.

In this drawing, I have a line, a rectangle, a text object, and an mtext object.

What's that? You only see a circle? Well, that's because the other objects are zero-length or empty. Let me press Ctrl+A now...

Ah, THERE they are. Let's fix that.

I'll launch Quick Select (from the Tools menu, Properties palette, or by typing QSELECT), set the object type to Line, the property to Length, and the value to 0.

Got it!

Now I can press Delete and get rid of it. Then I can repeat the process for the polyline, text, and mtext objects, except that the property for the text objects is Contents and the value is a space.

So that's how you'd get rid of empty objects prior to AutoCAD LT 2010 -- you can see why the new Purge option would be a real timesaver!

Purge Empty Objects

I love all the easy-but-cool features that found their way into AutoCAD LT 2010. Like editing non-associative hatch objects.

Another feature that I can just tell you about (instead of having to "teach" it) is the ability to purge zero-length geometry and empty text objects. It's a new box at the bottom of the Purge dialog.

Zero-length geometry can happen when you draw a line and put two points on top of each other, or when you draw a rectangle and put the first and second corner at the same point -- in other words, it's usually an accident. Same thing with empty text: maybe you erased the contents of a text object instead of deleting the object, or you typed a space and saved the object instead of undoing it.

These objects can be hard to find, because they're either tiny points or completely invisible. There are ways to track them down (Quick Select is one), but it's a lot easier to just check the box and make them all go away.