Circles and Lines: Super Speedy Selection Sets

12 Feb, 2006 By: Lynn Allen Cadalyst

So many options, so much more time.

AutoCAD (and LT) asks you to select objects countless times every day. Most of us are masters at windowing, using it as the panacea for all our select objects needs (even when it takes several windows to accomplish our goal). I, as the saving steps queen, thought it useful to review the other object selection alternatives .

Be warned -- you might just stumble across something that will save you time in your drawing routine. I published a similar article many years ago, but recent encounters during my travels made me realize it is definitely time to update this topic.

So Many Options
You have 17 options for selecting objects (yes -- 17!). That's a lot of options, and most of us only know about three or four of them. Back in the old days of AutoCAD, selecting objects was simple. The Command prompt read: Select objects, Window or Last. You had three options. Over the years Autodesk has tried to satisfy its users' wishes by adding new ones.

I'm sure you'll find many of these 17 options useful, and this column will hopefully encourage you to expand your selection set horizons. I've listed 16 of the many different options below. The 17th option is the simple pick to select an object (which of course you've already figured out). I'll discuss the different options one by one. I've listed them in the order they appear in the prompt.


I predict that most of you use two options 95% of the time: the automatic windowing and selecting the objects one at a time. Automatic windowing refers to the automatic standard and crossing windows that appear when you select a point on the screen where no object resides. Moving the window from left to right creates the standard window, right to left yields a crossing window. The standard window is solid in representation; the crossing window is dashed.

For those using AutoCAD 2006, you'll also see that a solid blue box indicates a standard window, dashed green for crossing. The standard window selects only those objects found completely within the selection window. A crossing window selects all objects that are completely within the selection window as well as those that cross the window. If one quarter of a line was within a crossing window with three quarters hanging out, the line would still be selected.

Selecting objects one at a time is simple. Place the pickbox on top of the desired object and pick. You can make the pickbox larger or smaller by using the Pickbox command. It is measured in pixels. For those of you who are bad shots or have had little time for your new Xbox, you might find it useful to enlarge the pickbox. When trying to get into tight areas, making it smaller can come in handy as well.

If the system variable PICKAUTO is off, you will not get the automatic windowing.

Rare Birds
Now let's look at the lesser-known (and rarely used) object selection methods. The upper case letter indicates the minimum needed to use that means of object selection.

Last: I often use this option. L is used to select the last object created in the current display.

Window: Technically you can key in a W to force a standard window selection (though we wouldn't bother with this anymore).

Crossing: Similar to Window, you can key in a C to force a crossing window selection.

Two in the Hand
The following two go hand in hand. They've traditionally been used in menus to force the automatic window we just covered. If the user accidentally turned PICKAUTO to off, the menu selection would still force the automatic windowing. It is doubtful you would ever need to use either of these in your daily AutoCAD life, but I'll cover them anyway.

AUto: Forces the automatic windowing discussed above. If the user picks in a location where no object resides, it goes into the Window/Crossing window mode. If the user picks in a location with an object, then that object is selected and no window appears.

BOX: Forced an automatic window only, even if the user selected on top of an existing object.

ALL: Use this option to select every darn object in your drawing. The only objects safe from this option are those on frozen or locked layers. I use this option on occasion as well.

Fence: Use the Fence option when it's easiest to draw a series of connected line segments through the desired objects (figure 1). Fences don't need to close, and they may cross themselves. You'll also find the Undo option in the Fence selection should you pick an incorrect endpoint. Fence is a great means of selecting multiple objects to trim or extend.

Figure 1. Use Fence to select the cyan colored lines only.

Think Outside of the Box
Crossing Polygon and Window Polygon are two great, underused selection secrets! The objects we wish to select don't always conveniently lie within a rectangular area. Hence, rectangular windows don't always do the trick. The CP and WP options allow you to create a polygonal area with as many sides and whatever shape you'd like. Rather then creating several windows to get the desired objects, try using these two options. CP selects all the objects within or crossing the polygonal area (figure 2). WP selects only those objects that fall completely within the polygon. You'll find the Stretch command lets you use the CP option (very handy!).

Figure 2. Use Crossing Polygon when objects lie in a non-rectangular area.

Both CP and WP must follow one rule -- the polygon may not cross or touch itself. AutoCAD continually sketches in the last segment to ensure a closed polygon. You'll find an Undo option should you accidentally select an incorrect location for a polygon vertex.

Group: Have you ever wanted to save a group of objects for future editing purposes? The Group command lets you do exactly that. You can name a group of objects to be used later as a selection set. You may also use this same group over and over again. I don't have the time to address this sizeable topic this month, but take a look at the Group command if this is one of your design needs. Should you create a group, you may call to it by using the G option. For example:

Select objects: g
Enter group name: desks

Add and Subtract
Add and Remove work together. They're used to add and subtract objects from an existing selection set of objects. Let's say you want to move all of the objects in one section save for a couple of objects right in the center. Do you painfully select the desired objects by using multiple windows? No! It's so much faster to select all of the objects in the section and then remove the one or two objects from the final selection set. The Remove option is used for this exact reason. When selecting the Remove option, you'll find the familiar Select objects prompt changes to Remove objects. Should you choose to return to the Select objects: prompt, you'll need to use the Add option.

Note: If someone has turned off the PICKADD variable, you only will have one chance to select objects. Due to this, you may see an occasional Add option added to menus to ensure the user has the opportunity to select more then once. It's doubtful that you (or anyone) would intentionally set this value to off.

Many releases ago, Autodesk added the nice Shift to Remove feature to AutoCAD. This feature is much easier to use then the Remove option because you don't have to key in R. Simply hold down the Shift key to remove objects from the selection set. While holding down the Shift key, you can also use automatic windowing. In this situation, you wouldn't need the Add option. This is a great feature that's still underutilized.

Previous is used to select the previous selection set (another one of my favorites). For example, let's say you wish to move and array a group of objects. You'll select the group of objects once for the Move command and use the Previous selection option when you enter the Array command. There's never any reason to select the same selection set over and over again.

Multiple: I believe this option remains in AutoCAD primarily due to legacy. This option permits the individual selection (by picking) many objects without highlighting the objects. It is intended to speed up the selection process. You pick and pick and hope you picked the correct objects. If you pick at an intersection twice, you should have selected both objects (though it doesn't always work). When you think you've selected all of the objects, you hit Enter and the objects become highlighted. Years ago, on the very slow machines, this option was occasionally used -- I don't hear of it being used today (please enlighten me if I'm wrong!).

SIngle is used primarily in menus. When entered, the user gets only one chance to select objects before the command progresses to the next step. I can think of no reason you'd use this option in your daily drawing routine.

Undo is obviously a popular one. Should you select the wrong objects, no need to cancel the operation and start over; just use the Undo option to deselect the last object(s) selected. Take the lazy route and don't do any more work than absolutely necessary!

One last point of interest in selecting objects is referred to as Object Cycling. Have you ever tried to pick an object but found that AutoCAD keeps grabbing the wrong one? Object Cycling to the rescue! You'll find that if you hold down the Control key while picking, AutoCAD will cycle through all the objects that fall under the pickbox as you continue to pick. When the correct object is highlighted, simply hit Enter. You don't need to continue to hold down the Control key after the first pick. Try it -- it's a great addition to your newfound selection set knowledge.

Is your mind now open to trying some of the other selection set options? You'll have to force yourself to get out of that automatic windowing habit (no CAD patch?), but I'm sure you'll find the advantages worthwhile. Happy AutoCAD-ing!

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