Learning Curve: Clever Grip Tricks14 Jul, 2005 By: Bill Fane Cadalyst
More editing tricks using grips
Once upon a time, in an AutoCAD tutorial not far away, we learned all about grip editing. Well, not all about it. As you will see this month, you can perform many more clever editing tricks using grips.
The first cunning trick is that grips also act as object snaps. To make this work, all you need to do is to select two or more objects while you are at the Command prompt. Select a warm (blue) grip to make it hot (red), then drag it towards a warm grip on another object. As you get close, the hot grip will snap to the warm grip (figure 1).
Figure 1. A grip editing sequence: A=selected, B=dragging a hot grip, C=snapped to a warm grip.
Okay, you need to do one or two other things first to make this work as shown. Specifically, you should turn off Ortho, Polar and Osnap. Ortho and Polar need to be turned off because they will override the grip snap action. Figure 2 shows the results of performing a grip snap when Ortho is on. The end of the left line is directly below the midpoint of the right line.
Figure 2. Grip editing when Ortho is turned on.
Strictly speaking, you do not need to turn off Osnap under the right conditions. To determine those conditions, we need to look at the effective snaps provided by grips.
A bit of experimentation will reveal that grips exist at the ends and midpoints of lines and arcs; the centers of arcs, circles and ellipses; the quad points of circles and ellipses; the vertices of polylines and splines (they are endpoints of the segments); the insertion points of blocks and text; and the defining location points of dimensions.
If your Osnap settings include end, mid, center, quad and insertion points, then you won't have a problem. On the other hand, if you have midpoint turned off and endpoint turned on, then figure 1 would not work. Having clicked on the midpoint grip, you would have selected the line, and then the endpoint object snap would have kicked in (figure 3).
Figure 3. Grip snapping with Osnap set to endpoint but not to midpoint.
Little-known Grip Facts...
A Peanuts comic strip showed Lucy unleashing a string of little-known scientific facts on Charlie Brown. "If they are so little known, how do you know them?" asked Charlie Brown, to which Lucy replied, "I make them up."
Okay, here are some little-known grip editing facts. No, I did not make them up.
So far, all our grip editing involved a single hot grip. Okay, try this: select several objects for editing. Before you click on a warm (blue) grip to make it hot (red), press and hold a Shift key. Now you can select several hot grips, and the grip edit will perform on all of them. It applies primarily to the Stretch editing mode because the other modes already work on multiple objects. The first grip you pick, hot or warm, without holding a Shift key down becomes the base, and all the other selected grips will stretch in unison relative to the base (figure 4).
Figure 4. Press and hold the Shift key to select multiple hot grips.
Grip editing allows us to build selection sets, just like any other editing command. You can select objects by picking, windowing or crossing. Repeated selections will add to the selected set.
You can also remove objects from the selection set. Simply hold the Shift key down while you pick objects (but not a grip) or while windowing or crossing.
The editing function then will be performed on all objects in the set for all functions except Stretch. It requires multiple hot grips as described above.
The base point for a grip edit does not have to be on a grip. Having selected one or more hot grips and an editing mode, you can then enter the letter B to specify a base point for the action. It can be anywhere in the drawing.
Direct Distance Entry (DDE) works with grips. Having selected a hot grip or grips, you can start to drag things in the desired direction, and then type in an exact value for the distance.
Pick me! Pick me!
If GripBlock is set to the default value of 0 (zero), then the only grip that will appear if a block insertion is selected will be at its insertion point. On the other hand, setting GripBlock to 1 (one) will cause grips to appear at every grippable location within the block. This does not allow you to stretch the objects within a block, but you can Move, Copy, Rotate or Scale the entire block relative to any of its internal grips.
You cannot grip the individual objects that make up a hatched area. If OsnapHatch is set to 1, then you can snap to them, but you still can't grip them. If you grip edit the boundaries of an associative hatch, then the hatching will update to reflect the new boundary.
Select two or more objects that meet at a common location, such as several lines, and then select a single hot grip at the common meeting point. The grip edit will be performed on all objects that meet at the hot grip.
If you hold down a Shift key while selecting the destination point, AutoCAD automatically turns on Ortho mode temporarily for as long as you hold the Shift key down.
The Rotate and Scale modes also have additional options to let you perform the action relative to a Reference dimension, so you can rotate or scale to exactly match an existing object.
At the completion of a grip edit function, all the grips remain active and all the original objects remain selected. Pressing Esc once at the Command prompt will unselect all objects and will return their grips to the cold (invisible) state.
When you are back at the Command prompt, Undo (or U) will reverse the action of the entire grip command sequence; it will remove all multiple copies in one fell swoop.
Normally, when you are at the Command prompt, you can just press Enter to repeat the last command. This does not apply to grip editing, however. If you press Enter, you will repeat the last command you used before you did the grip editing.
All in all, grips can greatly speed up your editing, to the extent that I rarely use the traditional commands.
And Now For Something Completely Different
When waxing your car, here is a little trick that will bring out the ultimate shine. Use a bit of corn starch on the lamb's wool buffer pad that you use for the final polishing operation. You should also note that older, ordinary cars go to a Show 'n Shine, whilst exotic and expensive cars attend a Concours d'Elegance.
About the Author: Bill Fane
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