Moving, copying, and stretching are, for many drafters, the three most common editing operations. AutoCAD obliges this need with the Move, CoPy, and Stretch commands.
The Move, CoPy, and Stretch commands all require that you specify how far and in what direction you want the objects moved, copied, or stretched. After you’ve selected the objects to be edited and started the command, AutoCAD prompts you for two pieces of information:
Specify base point or displacement:
Specify second point of displacement or <use first point as displacement>:
In a not-so-clear way, these prompts say that two possible methods exist for you to specify how far and in what direction you want the objects copied, moved, or stretched:
? The most common way is to pick or type the coordinates of two points that define a displacement vector. AutoCAD calls these points the
? The other way is to type an X,Y pair of numbers that represents a distance rather than a point. This distance is the absolute displacement that you want to copy, move, or stretch the objects (thus it’s called the “displacement method”).
How does AutoCAD know whether your response to the first prompt is a base point or a displacement? It depends on how you respond to the second prompt. (Is that confusing, or what?) First, you pick a point on-screen or enter coordinates at the Base point prompt. Next, there are a couple of possibilities:
? If you then pick or type the coordinates of a point at the second point prompt, AutoCAD says to itself, “Aha — displacement vector!” and moves the objects according to the imaginary arrow pointing from the base point to the second point.
? If you press Enter at the second prompt (without having typed anything), AutoCAD says, “Aha — displacement distance,” and uses the X,Y pair of numbers that you typed at the first prompt as an absolute displacement distance.
What makes this displacement business even more confusing is that AutoCAD lets you pick a point at the first prompt and press Enter at the second prompt. AutoCAD still says, “Aha — displacement distance,” but now it treats the coordinates of the point you picked as an absolute distance. If the point you picked has relatively large coordinates, the objects can get moved way outside the normal drawing area as defined by the limits. The objects fly off into space, which you probably won’t notice at first because you’re zoomed into part of your normal drawing area; it just looks to you like the objects have vanished!
In short, be careful when you press Enter during the Move, CoPy, and Stretch commands. Press Enter in response to the second prompt only if you want AutoCAD to use your response to the first prompt as an absolute displacement. If you make a mistake, click the Undo button to back up and try again. You can use Zoom Extents (described in Chapter 7) to look for objects that have flown off into space.
The following steps demonstrate command-first editing with the Move command, using the base point method of indicating how far and in what direction to move the selected objects. This procedure also gives detailed recommendations on how to use precision techniques when you edit:
1. Press Esc to make sure that no command is active and no objects are selected.
2. Click the Move button on the Modify toolbar.
The command line displays the Select objects prompt.
3. Select one or more objects.
You can use any of the object selection techniques described in the “Perfecting Selecting” section, earlier in this chapter.
4. Press Enter when you’re finished selecting objects.
AutoCAD displays the following prompt:
Specify base point or displacement:
5. Specify a base point by clicking a point or typing coordinates.
This point serves as the tail end of your imaginary arrow indicating how far and in what direction you want the objects moved. After you pick a base point, it’s fairly easy to see what’s going on because AutoCAD displays a temporary image of the object that moves around as you move the cursor. Figure 6-4 shows what the screen looks like.
Figure 6-4: Dragging objects in the middle of the MOVE command.
Specify a base point somewhere on or near the object(s) that you’re moving. You can use an object snap mode to choose a point exactly on one of the objects.
AutoCAD displays the following prompt:
Specify second point of displacement or <use first point as displacement>:
6. Specify the second point by clicking a point or typing coordinates.
The second point serves as the arrow end of your imaginary displacement arrow. After you specify the second point, AutoCAD moves the objects.
Don’t press Enter alone at this prompt! If you do, AutoCAD treats the X,Y coordinates of the first point you picked as an absolute displacement, and the objects fly off in an unpredictable fashion.
These are common precision techniques for specifying the second point:
? Use an object snap mode to pick a second point exactly on another object in the drawing.
? Type a relative or polar coordinate, as described in Chapter 4. For example, if you type @6,2, AutoCAD moves the objects 6 units to the right and 2 units up. If you type @3<45, AutoCAD moves the objects 3 units at an angle of 45 degrees.
? Use direct distance entry to move objects in an orthogonal or polar tracking direction. See Chapter 4 for instructions.
The CoPy command works almost identically to the Move command, except that AutoCAD leaves the selected objects in place and moves new copies of them to the new location. The CoPy command also includes a Multiple option for making multiple copies of the same set of objects. You activate the Multiple option by typing M and pressing Enter after you finish object selection. As always, you must watch the command line prompts to find out what you can do and when to do it!
You can’t copy objects from one drawing to another with the CoPy command. Instead, you use the COPYCLIP command, together with its companion command, PASTECLIP. Follow these steps:
1. Open two drawings that contain geometry you want to copy from one to the other. Arrange the two drawings so that you can see both of them, as shown in Figure 6-5.
Figure 6-5: Copying objects between drawings.
If you don’t have enough screen real estate to arrange the two drawings side by side, you can leave them overlapped and change between the two drawing windows by using the Window menu or by pressing Ctrl+Tab.
2. In the first drawing, right-click in the drawing area and choose Copy from the cursor menu.
Choose Cut if you want to move rather than copy the objects to the other drawing. Choose Copy with Base Point if you want to choose a specific base point rather than let AutoCAD choose a base point.
The base point that AutoCAD chooses is the lower-left corner of an imaginary rectangle that just barely encloses all the objects you’ve selected.
