LT Unlimited

Join Objects

The JOIN command is another feature in AutoCAD LT 2012 that isn’t new, but that’s been tweaked so it’s more useful than ever.

The basic idea behind Join is that you can combine two or more objects into a single object. Here are some possible combinations:

• Collinear lines (with or without gaps) –> line
• Non-collinear lines (without gaps) –> polyline
• Single arc –> circle
• Multiple arcs (same center & radius) –> arc or circle
• Lines & arcs –> polyline
• Lines & arcs & splines –> spline

Generally speaking, the most complicated object wins. So if you join lines, arcs, and a polyline, the result is a polyline. If your set includes a spline, the result will be a spline.

The change for 2012 is that you can select your objects for joining in any order, or even select multiple objects at once with a crossing or selection window. AutoCAD LT will automatically figure out which objects can be joined and what the resulting object type will be.

Object Snap Enhancements

AutoCAD LT 2012 includes a small improvement to the Perpendicular and Tangent object snaps that I think might go unnoticed if it weren’t pointed out, but could still be helpful for those of you who need it.

When you’re grip-stretching a line or polyline and using the Perpendicular object snap, you now get two options for the snap point.

First, you can make one of the segments perpendicular to another line.

  

Or you can make the stretching vector perpendicular to another line.

In earlier versions, you’d only get one or the other, but now you can have both.

A similar principle applies to tangent snaps too. You can either grip-stretch a line so that it becomes tangent to the arc or circle, or the stretching vector can be the tangent instead.

Facelift for the Group Command

This is kind of a sneaky “new features” post, because Groups are by no stretch of the imagination “new”. They’ve been around since…well, I’m not exactly sure how long. Essentially forever, or at least that’s what it feels like.

But in AutoCAD LT 2012, the Group feature has been revamped and been given a place of prominence on the Home tab.

If you’re a long-time groups user, this change just makes it that much easier to find the commands you’re used to. And if you’ve never used groups before…it makes it that much easier to find a “new” command. (Sort of like styles in Word. I never used them before they were put front and center on the Word ribbon—and now I never create a document without them.)

So, what is a group, anyway? It’s a collection of objects that you can select and manipulate as a unit. It’s sort of like a block, except a group is easier to create and un-create, doesn’t have to have a name, and is designed for temporary use in a single drawing.

These days, all you have to do to create a group is click on the largest icon in the Groups panel, select your objects, and finish. Then, when you select any of the objects in the group, they’re all selected.

Here’s a before-and-after screenshot:

 

Notice that the group now has a single center grip, and a gray “bounding box” around the outside edge. (The bounding box is easiest to see where it crosses the door to the cubicle, but trust me, it goes all the way around.)

You can move, copy, scale, rotate, or mirror this group without having to select each object every time.

But what if you want to make some changes to the group—add or remove objects, or change the position of individual items? Look back up at the panel.

The icon in the top right is for Ungroup, which the group version of Explode. It just removes the group association so you can select everything individually.

Below that is Group Edit, which lets you add objects to the group or remove objects from it.

At the bottom is Group Selection, which determines whether objects remember their group association or not. If you turn it off, it’s as if the group doesn’t exist. You can make any kind of modifications to the objects in the group, and when you turn Group Selection back on, the original association is restored.

Personally, though, using Group Selection seems a little extreme to me. I think it’s a little risky to pretend you don’t have any groups at all in your drawing when you do—you might be surprised by some results down the road.

Instead, I’d rather use something on the expanded portion of the Groups panel: the Bounding Box:

When it’s on, as it is in the image on the right above, selecting a group results in a single grip with the light gray outline around all the objects.

When it’s off, selecting any single item in the group selects all the items, but they still have all their grips visible. It would look the same as in the image above on the left. That way, you can use grip-edit methods to modify individual items, but general commands like Move and Rotate would still work on the group as a whole.

What do you think—will this new Groups panel make you more likely to incorporate groups into your workflow?

Blend Objects

A new command has been added to the Fillet drop-down in AutoCAD LT 2012.

BLEND is related to FILLET and CHAMFER, but it creates smooth splines between objects instead of lines or arcs.

Before and after:

     

The shape of the spline is almost entirely determined by the position and angle of the two objects it’s connecting.

You do have a choice of continuity, though: Tangent, which creates “a degree 3 spline with tangency (G1) continuity”; and Smooth, which creates “a degree 5 spline with curvature (G3) continuity”. The method you choose will affect the shape of the spline at least slightly, so unless you know in advance which one you need you can try both to see which one you like better.

New Option in Copy Command

You may have heard by now that the Array function has seen a major upgrade in AutoCAD LT 2012. (I’ll have a post with the details soon.) But it also turns out that Array wasn’t content to stay in its own corner – it had to expand into Copy too.

You can find this new option after you select your objects and pick your base point like always. But before specifying the second point, enter A instead.

Then you can enter the number of items in the array, and see a live preview of what the results will be. You can finish the array by either clicking to set the spacing between objects, or by using the Fit option to specify the total length of the array.

It’s a little hard to tell in the image above, but the line on the right is the original, and the 7 to the left are the arrayed copies.

The result of this kind of array is a bunch of separate objects. They’re not associative like the other new kinds of array. But it can still be quicker than using the regular multiple copy or offset commands.

Use Lengthen to Shorten

Ever heard the saying “sometimes you have to go backwards to go forwards”? It means that the most obvious path isn’t always the best.

I thought about that when I read a tip from Cadalyst about lengthening objects to make them shorter.

Usually when you think of “lengthening” objects, you think about making them longer. But the LENGTHEN command in AutoCAD LT can be used to make a line, polyline, spline, or arc longer or shorter.

When you start LENGTHEN, you’re given four options: DElta, Percent, Total, and DYnamic. You can also click on an object to see its current length.

For Delta, you provide the change in length or angle – positive numbers make things longer, negative numbers make things shorter. Once you’ve specified the increment, click close to the end you want to change.

With Percent, you specify the proportional change. Numbers less than 100 shorten objects; numbers greater than 100 extend them.

If you know the actual finished size you want, you can use Total. Again, the number you enter can be bigger or smaller than the current object – doesn’t matter which.

The last option is Dynamic. With this option, you get a live preview that extends or trims the object as you move your cursor. It’s the best visual of the four options, but the least precise.

Not all objects work with all options. For example, you can’t lengthen a spline with the Dynamic option, and you can’t use Angle with lines. If you’re not sure if something will work, try it. Either it’ll work, or you’ll get a message telling you why it didn’t. And either way, you’ll know for next time.

Break or Split Objects

I’m heading over to the Modify panel today to talk about two related buttons there – Break and Break At Point.

The regular Break command inserts a gap between two points on an object, splitting it into two new objects.

By default, the click you use to select the object to be broken is the same as the click that defines the first point of the break.

You can either accept that first point (which may or may not be accurate enough) and click again to specify the second point, or enter F to pick a new, more precise first point and then the second point.

Break points don’t have to be actually on the object. If you click nearby instead, that point is projected onto the object. Of course, you can always use object snaps to help you be more precise.

Here’s an arc, before and after being broken:

It is also possible to simply split an object into two, without creating a gap. One way is to pick the first point as usual, then enter “@” when prompted for the second point. This reuses the coordinates of the last pick.

Or, you can use the “Break At Point” button found next to Break on the Modify panel. This command – actually a macro – does the work of setting the “first” and “@” options for you, so you only have to pick one point on the object to create the split.

Here’s the arc again, this time split with the “Break At Point” function:

(I had to show you the arc selected here, or you might not have believed me that I actually broke it!)

Match Hatch Properties

The ability to set the properties of a new hatch to match those of an existing one has been around for a long time. Before 2011, this tool was called “inherit properties” and it was limited to hatch-specific properties like pattern, angle, and scale.

AutoCAD LT 2010 hatch preview, before “inherit properties” (current layer color is white, existing hatch layer color is red):

AutoCAD LT 2010 hatch preview, after “inherit properties”:

In AutoCAD LT 2011, this feature has been renamed to “Match Properties” because it behaves much more like the regular “Match Properties” command. Now, whether you’re creating or editing a hatch, you can match ALL the properties of another hatch, including color, background color, and layer. You can even choose whether you want to use the current value for the new hatch’s origin or use the origin of the hatch you’re matching.

AutoCAD LT 2011 hatch preview, before “match properties” (current layer color is white, existing hatch layer color is red, hatch layer is set to “use current”):

 

AutoCAD LT 2010 hatch preview, after “match properties”:

Twitter Tip of the Day: Multi-Functional Grips

This morning on Twitter, Brian Benton (@bcbenton) asked “In #AutoCAD 2011, when selecting a Polyline, can the "Stretch, Add Convert" box be turned off temporarily?”

A few minutes later, he answered his own question (albeit on Facebook): “GRIPMULTIFUNCTIONAL set to 0 or 1.”

Rather than leave it there, though, I thought I’d expand on the other options for this particular system variable.

GRIPMULTIFUNCTIONAL can actually be set to 0, 1, 2, or 3. (The default is 3.)

1. Access to multi-functional grips is disabled. With this setting, you lose any object-specific grip functions, and can only use the standard Stretch/Move/Rotate/Scale/Mirror.
2. Access multi-functional grips with Ctrl-cycling and the Hot Grip shortcut menu. This means that you have to left-click on a grip first, then either press Ctrl to cycle through the options or right-click to pick one from a shortcut menu.
3. Access multi-functional grips with the dynamic menu and the Hot Grip shortcut menu. With this value, you can either hover over a grip before clicking to see the menu and pick an option, or you can left-click on a grip and then right-click to bring up the shortcut menu. Pressing Ctrl with an active grip has no effect.
4. Access multi-functional grips with Ctrl-cycling, the dynamic menu, and the Hot Grip shortcut menu. Provides the most options for accessing multi-functional options. Hover over a grip to pick from the dynamic menu, left-click a grip and press Ctrl to cycle, or left-click a grip and right-click for a shortcut menu.

I’m really not sure why anyone would choose 0 (multi-functional grips are great!) or 2 (leaving Ctrl-cycling on doesn’t really hurt anything, does it?), but you could use 1 if you really don’t like pop-up menus.

Updates to the Spline Command

The new 3D modeling tools in AutoCAD 2011 required some updates to the spline command, and while a lot of them are most applicable to 3D situations, some of them have trickled over to the 2D side.

You’ll notice the first change right after you start the command, if you pay attention to the options at the dynamic prompt or command line.

“Object” has been around for a while (it turns a polyline into a spline), but “Method” and “Knots” are new to AutoCAD LT 2011.

“Method” lets you choose between “Fit Points” and “Control Vertices.” Fit Points is the old familiar way, where the spline passes through each point that you select. With Control Vertices (CV), you essentially define bounding lines and the spline fits between them. (That’s an overly simplistic explanation, but let’s just say that CV splines are important for 3D modeling, and you should go check out Guillermo Melantoni’s What A Mesh blog if you want to know more.)

Here are examples of the two methods, first with fit points, then with CV.

Whichever method you choose, you can change the display later.

Knots affect the shape of a fit spline as it passes through fit points. There are 3 options (Chord, Square Root, and Uniform), but I’m honestly not sure how to explain the differences.

Maybe the biggest change you’ll notice is that when drawing a fit spline, the start and end tangencies are now assumed. You can change it with the Tangency options if you want to, but you don’t have to. (Admit it – when you finish a pre-2011 spline, you just hit Enter-Enter-Enter anyway, right?)

Splines also have some new fancy grips, and they’re multifunctional like the ones for polylines and hatches.

The options you’ll see are a little different depending on whether you’re working with a fit spline or a CV one, but the concept is the same.

In the image above, the triangular grip is for switching between Fit and CV display. The “plus” on the left-hand grip indicates the beginning of the spline (to help identify “start” and “end”). For the square grips, you can stretch, add, and remove fit points, and for the start/end grips you can change the tangent direction.