Learning Curve: Get a Grip on Editing with Grips14 Jun, 2005 By: Bill Fane Cadalyst
Learn how AutoCAD's grips make editing faster and easier
It was a lovely warm spring afternoon. The sun was shining, the birds were singing, income taxes needed filing.
Captain LearnCurve's mind began to wander, as he thought of all the fun things he could be doing. Nope, got to get a grip on reality and get to work on this month's article. Now for a topic?
That's it! Grips! I haven't written about grips since 1993 when they were introduced in Release 12.
The topic of grips actually includes two subjects. One is grip editing itself, and the other is noun-verb versus verb-noun editing.
Most of you make extensive use of the editing commands such as Move, Copy, Erase, Rotate, Trim, Extend, Mirror and so on. They are some of the commands that give AutoCAD its power. In fact, one thing I teach my students is that it is often faster to do it wrong and correct it than it is to do it right the first time. For example, you can copy or mirror a detail that is almost what you want and then change it faster than you can draw it from scratch.
Two Ways to Edit Objects
Some CAD programs use a verb-noun sequence. You issue a command such as Move (the verb), and then pick the objects to be moved (the nouns). Traditional AutoCAD works this way.
Other programs use a noun-verb sequence. You select the objects first, and then issue the command. SolidWorks, for example, makes extensive use of this sequence.
Since Release 12, AutoCAD has given us the luxury of working either way. For example, if you start the Move command (the verb), AutoCAD asks you to Select Objects (the nouns). It then asks for a base point and second point (the adjectives) for the Move and completes the operation.
On the other hand, observe what happens when you are sitting back at the Command prompt and you pick an existing line in your drawing. Two things happen: the line becomes highlighted (dotted) to indicate that it was selected, and three little blue boxes appear on it -- one at each end and one in the middle. AutoCAD remains at the Command prompt.
Figure 1 shows this phenomenon, and it also shows the new rollover indicator. In AutoCAD 2006, an object fattens up as you roll over it to indicate that it would be selected if you clicked at that point.
Figure 1. Unselected, rollover and selected states.
Now start the Move command again and AutoCAD doesn't ask you to Select Objects, but instead turns off the blue boxes and jumps straight to the Base Point and Second Point prompts.
In this noun-verb mode, you tell AutoCAD which objects it should edit and then tell it what to do with them.
When you finish the command, the highlighting goes away to indicate that there is no longer a pending selection set.
Note that AutoCAD is smart enough to automatically switch between verb-noun and noun-verb modes depending on what you do first.
In either case, AutoCAD remembers the selected objects as a Previous set. Whether you used noun-verb or verb-noun, you can always go back and use the Previous selection set for any appropriate editing command.
The noun-verb mode can't be used with all editing commands. It only works with editing commands that can operate on a group of objects such as Move, Copy, Array, Block, Scale and so on. The commands that operate on only one or two objects -- such as Break, Fillet, Offset, etc. -- ignore and cancel any pre-selected objects and ask for specific objects.
You can turn off noun-verb mode by issuing the PickFirst command. Responding with a 0 (zero) turns it off; a 1 (one) turns it on. I don't know why you would turn it off under normal circumstances. When off, it only allows verb-noun; but when on, it automatically uses either as appropriate.
Get a Grip
So what, you may ask, are grips? They are the little blue boxes that appear all over pre-selected objects.
When you edit a drawing, have you noticed how often you use a third function? Not only do you select objects and start an editing command (or the reverse), but you also nearly always use, or should use, object snaps such as ENDPoint, INTersection, MIDdle and so on.
Well, grips roll all three basic operations into one simple lump. As noted earlier, when you select objects while at the Command prompt, not only do they become highlighted (dotted), but they also grow little blue boxes. These boxes appear at the ends, center, middle and/or insertion points of the selected objects.
You already saw that you can pre-select objects and then initiate an editing command (noun-verb), but you can also have AutoCAD initiate certain editing commands automatically.
Types of Grips
One or more grips are associated with every object in a drawing. Normally, they are invisible, which are called cold grips.
Draw three or four separate lines. At the Command prompt, select a line. It becomes dotted and grows a blue box at each end and one in the middle. The boxes are now warm grips. They are like little handles, just waiting for you to grab them.
Now move the cursor until the pick box at the cursor intersection coincides with the blue box at one end of the line. In current releases as you hover over a blue box, it turns green to indicate that it recognizes your presence.
Pick a blue box, and it turns red to indicate that it is now a hot grip.
While you're at it, take a look at the Command prompt area at the bottom of the screen. You are already in the Stretch command! Move the cursor, and the line automatically stretches (or shrinks) to follow. Pick a point, and the end of the line anchors to the new location. Figure 2 shows this action in progress.
Figure 2. You can drag a grip to a new location, and its associated object point will follow.
Note that the end that moved was the exact end of the line, just as if you had used an object snap to select it. In fact, running object snaps don't even have to be on for this to work. Grips are also automatic snap points.
Performing this edit with traditional commands would require about 10 mouse picks and key presses. You would have to start the Stretch command, and then start a Crossing window and pick two points that boxed the end of the line, and then press Enter to stop selecting objects, then invoke the object snap ENDPoint and pick one end of the line, and finally pick the destination point.
With grip editing you only need to pick the line, the grip at one end and the destination point.
What if we don't want to stretch the line? No problem! Pick the line and then the grip at one end of it. When AutoCAD offers the Stretch command, just ignore it and repeatedly press the space bar or the Enter key.
AutoCAD scrolls in a loop through the available editing commands in the sequence Stretch, Move, Rotate, Scale and Mirror. Notice that Copy is not in the list. Just stop when you get to the one you want. You can also jump directly to the desired function by right-clicking and then picking it from the context menu that appears.
Now, notice the prompt that appears in the Command area at the bottom of the screen. (That is not a suggestion; it is a direct order. You WILL notice the prompt!)
It is nearly the same for each option, so I'll just go through it once.
First, it shows a prompt in Angled Brackets, which is the default and is a little different for each editing command. It asks for a Stretch to Point, a Move to Point, a Scale Factor or whatever is appropriate.
Type in a coordinate pair (or a number for the scale factor or rotation angle) or pick a point using the mouse. In the latter case, the location of the picked point is controlled by any Snap setting, or if Ortho or Polar are on, or if any running Osnap modes are on, or any object snaps you specify.
Then the desired editing action occurs between the base grip and the selected point.
Now let's look at some other options. You can invoke them by typing in the upper-case letter (usually the first) of the desired option or by right-clicking and then picking from the context menu.
Base Point lets you define a base point different from the base grip.
Copy is a powerful one. Remember earlier we noticed that Copy was not in the function list? Here is why: the Copy option lets you make multiple copies from within any other function!
That's right; you can Stretch multiple new lines radiating out from the base of the first one, or rubber-stamp multiple Moves, or Mirror several copies about different mirror lines or Rotate multiple copies (figures 3 and 4).
Figure 3. Using the Copy option, you can grip stretch multiple copies in one run.
Figure 4. You can copy as you move to multiple locations.
Undo lets you step back through multiple copies while you're still within the one run of the command, removing each one in turn.
This article is getting a little long, so come back next time when we dig a little deeper into the amazing Grip functionality. As you'll see, it will rapidly become your main editing mode.
And Now For Something Completely Different...
Just because a wristwatch is labelled "water resistant to 100 meters" (about 330 feet) does not make it a diver's watch. Most of them flood if you press a button on them in as little as 20 feet of water. This can easily happen when the cuff of your wet suit brushes against a button.