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Chapter 7: Edit for Credit 161
Choosing an editing style
This chapter emphasizes command-first editing. (We also discuss grip editing at the end of the chapter.) AutoCAD is fundamentally a command-first program. AutoCAD started out offering only command-first editing and later added selection-first methods; AutoCAD 2007 inherits this ancestral trait. We emphasize command-first editing for the following reasons:
It’s the default AutoCAD editing style.
^ It works consistently with all editing commands — some editing commands remain command-first only.
^ It provides added object selection flexibility, which is useful when you work on complicated, busy drawings.
After you know how to do command-first editing, you can simply reverse the order of many editing operations to do them selection-first style instead. But if you don’t get familiar with command-first editing in the beginning, you’ll be completely bewildered by some very useful AutoCAD commands that work only in the command-first style, such as FILLET (F) and STRETCH (S). (Commands such as these ignore any already selected objects and prompt you to select objects.)
Much of the information in this chapter assumes that you’re using the default AutoCAD selection settings. If object selection or grip editing works differently than we describe in this chapter, check the settings on the Options dialog box’s Selection tab. The seven check box settings listed next and shown in Figure 7-1 should be turned on. (All other check box settings should be turned off.)
^ Selection Preview When a Command Is Active ^ Selection Preview When No Command Is Active ^ Noun/Verb Selection ^ Implied Windowing ^ Object Grouping ^ Enable Grips ^ Enable Grip Tips
For information on what these options do, click the small question mark button beside the Close button at the top-right corner of the Options dialog box, and then click one of the options.
162 Part II: Let There Be Lines
Setting selection options in the Options dialog box.
Part of AutoCAD’s editing flexibility comes from its object selection flexibility. For example, command-first editing offers 16 selection modes! (We describe the most useful ones in this chapter.) Don’t worry though; you can get by most of the time with three selection modes:
Selecting a single object
Enclosing objects in a window selection box (pick left corner and then right corner)
Including part or all objects in a crossing selection box (pick right corner and then left corner)
The most obvious way to select objects is to pick (by clicking) them one at a time. You can build up a selection set cumulatively with this pick-one-object-at-a-time selection mode, but this cumulative convention may be different from what you’re used to. In most Windows programs, if you select one object and then another, the first object is deselected, and the second one selected. Only the object you select last remains selected. In AutoCAD, all the
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objects you select, one at a time, remain selected and are added to the selection set, no matter how many objects you pick. (You can change this behavior to make AutoCAD work like Windows does by turning on the Use Shift to Add to Selection option on the Option dialog box’s Selection tab, but we suggest that you don’t change it.) Most editing commands affect the entire group of selected objects.
Selection boxes left and right
Selecting objects one at a time works great when you want to edit a small number of objects, but many CAD editing tasks involve editing lots of objects. Do you really want to pick 132 lines, arcs, and circles, one at a time?
Like most Windows graphics programs, AutoCAD provides a selection window feature for grabbing a bunch of objects in a rectangular area. As you may guess by now, the AutoCAD version of this feature is a bit more powerful than the similar feature in other Windows graphics programs and, therefore, slightly confusing at first. AutoCAD calls its version implied windowing.
If you click a blank area of the drawing — that is, not on an object — you’re implying to AutoCAD that you want to specify a selection window, or box. If you move the crosshairs to the right before picking the other corner of the selection box, you’re further implying that you want to select all objects that reside completely within the selection box. If you move the crosshairs to the left before picking the other corner of the selection box, you’re implying that you want to select all objects that reside completely or partially within the selection box.
The AutoCAD terminology for these two kinds of selection boxes gets a little confusing:
The move-to-the-right, only-select-objects-completely-within-the-box mode is called window object selection.
The move-to-the-left, select-objects-completely-or-partially-within-the-box mode is called crossing object selection.
Fortunately, AutoCAD gives you visual cues that there’s a difference. As you move to the right, the window box appears as a rectangle with blue fill and a solid border. As you move to the left, the crossing box appears as a rectangle with green fill and a dashed border.