Perfecting Selecting
When you edit in command-first mode, you have all the selection options described in the previous section — single object, window box, window polygon, crossing polygon, and crossing box — plus a slew of others. If you type ? and press Enter at any Select objects prompt, AutoCAD lists all the selection options at the command line:
Window/Last/Crossing/BOX/ALL/Fence/WPolygon/CPolygon/
Group/Add/Remove/Multiple/Previous/Undo/AUto/
SIngle/SUbobject/Object
Table 10-1 summarizes the most useful command-first selection options.
Table 10-1 Some Useful Command-First Selection Options
| Option | Description |
| Window | All objects completely within a rectangular area that you specify by picking two points |
| Crossing | All objects within or crossing a rectangular area that you specify by picking two points |
| WPolygon | All objects completely within a polygonal area whose corners you specify by picking points |
| CPolygon | All objects within or crossing a polygonal area whose corners you specify by picking points |
| Fence | All objects touching an imaginary polyline whose vertices you specify by picking points |
| Last | The last object you drew (whether or not it's visible in the display) |
| Previous | The previous selection set that you specified |
| ALL | All objects on layers that aren't frozen or locked and that are in the current space (model space or paper space) |
To use any of the command-first selection options at the Select objects prompt, type the uppercase letters indicated in Table 10-1 that correspond to the desired option and press Enter. After you're finished selecting objects, you must press Enter again to tell AutoCAD that you've finished selecting objects and want to start the editing operation.
After you're finished selecting objects, you must press Enter again to tell AutoCAD that you've finished selecting objects and want to start the editing operation. Say … is there an echo in here? As a matter of fact, I am repeating myself. One of the things that most new AutoCAD users find hardest to remember is the necessity of pressing Enter after you finish selecting objects.
AutoCAD's Selection preview features remove a lot of doubt about which objects you're selecting. Rollover highlighting displays individual objects with a thick, dashed lineweight as you move the crosshairs over them. Area selection displays a transparent, colored highlight over multiple selections when you use Window and Crossing options. You can enable and disable both features on the Selection tab of the Options dialog box (refer to Figure 10-1).
The following example demonstrates how to use the ERASE command in command-first mode with several different selection options. The selection techniques used in this example apply to most AutoCAD editing commands.
- Open a drawing that contains some objects, or start a new drawing and create some lines, arcs, or circles.
You needn't be too particular drawing these because you're going to blow them away in the following steps.
- Press Esc to make sure that no command is active and no objects are selected.
If any objects are selected when you start an editing command, the command, in most cases, will operate on those objects (selection-first editing) instead of prompting you to select objects (command-first editing). For the reasons that I describe in the section “Commanding and Selecting,” earlier in this chapter, I recommend that you use command-first editing style until you're thoroughly familiar with it. Later, you can experiment with selection-first editing if you like. (Just reverse the sequence of commanding and selecting that I describe in this chapter.) 
Click the Erase button on the Home tab's Modify panel.
AutoCAD displays the Select objects prompt at the command line and, if Dynamic Input is enabled on the status bar, the Dynamic Input tooltip.
- Select two or three individual objects by clicking each one.
AutoCAD adds each object to the selection set. All the objects you select remain highlighted, and AutoCAD continues to display the Select objects prompt.
- Specify a window selection box that completely encloses several objects.
Move the crosshairs to a point below and to the left of the objects, click, release the mouse button, move the crosshairs above and to the right of the objects, and click again.
All objects that are completely within the box are selected.
- Specify a crossing selection box that completely encloses a few objects and cuts through several others.
Move the crosshairs to a point below and to the right of some of the objects, click, release the mouse button, move the crosshairs above and to the left of some of the objects, and click and release again.
All objects that are completely within or cross through the box are selected. AutoCAD continues to display the Select objects prompt.
- Type WP and press Enter to activate the WPolygon selection option.
AutoCAD prompts you to pick points that define the selection polygon.
- Pick a series of points and press Enter.
Figure 10-5 shows an example. After you press Enter, AutoCAD selects all objects that are completely within the polygon. AutoCAD continues to display the Select objects prompt until you press Enter.
- Press Enter to end object selection.
AutoCAD erases all the selected objects and returns to an empty command prompt.
Notice how you could use a combination of object selection methods to build a selection set and then press Enter to execute the command on the selected objects. Most AutoCAD editing commands work this way in command-first mode.
Figure 10-5: Lassoing objects with a WPolygon.
If, after erasing a selection set, you immediately realize that you didn't really mean to do away with so many objects, you can use the Undo button on the Quick Access Toolbar to restore them all. But AutoCAD has one additional unerase trick up its sleeve — the aptly named OOPS command. When you type OOPS and press Enter, AutoCAD restores the last selection set that you erased — even if you've run other commands after ERASE.
The ERASE command isn't the only way to remove unwanted objects from your drawing. Easiest of all in any workspace is to simply select an item and press the Delete key.
It's all too easy to draw objects on top of other objects, and once they're there, pretty well impossible to recognize that there are multiples so you can weed out the ones you don't want. For the last couple of releases, holding down the Shift key and the spacebar together while clicking on suspected multiple objects will highlight them, one after the other; when the one you're after lights up, you press Enter to select it. AutoCAD 2011 introduced a more powerful selection cycling method. With Selection Cycling enabled on the status bar, AutoCAD displays a blue icon showing overlapping rectangles if it detects multiple objects under your crosshairs. And when you pick an object with this icon displayed, AutoCAD opens a Selection dialog box where you can choose the object you actually want to.
AutoCAD 2011 could find those duplicates, and now AutoCAD 2012 will blow them away for you! Click the new Delete Duplicate Objects tool (look for the broom on the Modify panel slideout on the Home tab) to run the aptly named OVERKILL command. You can process an entire drawing at one fell swoop by entering ALL at the Select Objects prompt. The Delete Duplicate Objects dialog box appears; there you can set a number of properties and options (see Figure 10-6). Check the online help for more about this command.
AutoCAD LT users, for some strange reason, the tool button I describe in the preceding paragraph may not have made it onto LT's Modify panel. However, you do have access to the command — you just need to type OVERKILL at the command prompt to call up the Delete Duplicate Objects dialog box.
Like most graphics programs, AutoCAD lets you select a bunch of objects and gather them into a group, so that when you click on one object, everything in the group is selected. The new Groups panel on the Home tab of AutoCAD 2012's Ribbon offers a welcome update for the old and complicated Object Grouping (AutoCAD) and Group Manager (AutoCAD LT) dialog boxes. You simply select your objects and click Group. If you want, you can name your group as you create it. The buttons on the main Groups panel let you create new groups, toggle group selection off and on, edit groups by adding or removing individual objects, or permanently ungroup a selected group.
Clicking Group Manager in the Groups panel slideout displays the old Object Grouping (in AutoCAD) or Group Manager (in AutoCAD LT) dialog box for even more group functions.
