Before ending this chapter you will want to know about two other tools that are extremely useful in your day-to-day work with AutoCAD: selection filters and the Calculator. The discussion of these tools is saved until the end of this chapter because you don’t really need them until you’ve become accustomed to the way AutoCAD works. Chances are you’ve already experimented with some of the Auto- CAD menu options not yet discussed in the tutorial. Many of the pull-down menu options and their functions are self-explanatory. Selection Filters and the Calculator however do not appear in any of the menus and require some further explanation:
Let’s start with selection filters. There are.actually two selection-filtering tools in AutoCAD. The Quick Select tool offers a quick way to locate objects based on their properties. The Filter tool lets you select objects based on a more complex set of criteria .
Working with the Object Selection Filters Dialog Box
To use the Object Selecpon Filters dialog box, first select the criteria for filtering \ from the pull-down list. If the criteria you select is a named item (layers line types colors or blocks) you can then click the Select button to choose specific items from a list. If there is only one choice the Select button is dimmed.
Once you’ve determined what to filter, you must add it to the “listby clicking the Add to List button. The filter criteria then appears in the list box at the top of “” the Object Selection Filters dialog box. Once you have something in the list box you can then apply it to your current command or to a later command. AutoCAD remembers your filter settings so if you need to reselect a filtered selection set you don’t have to redefine your filter criteria
Saving Filter Criteria
if you prefer you can pre select filter criteria. Then at any Select objects : prompt you can click Selection Filters on the toolbar (or type ‘FiIter..J) highlight the appropriate filter criteria in the list box and click Apply. The specifications in the Object Selection Filters dialog box remain in place for the duration of the rent editing session.
You can also save a set of criteria by entering a name in the input box next to the Save As button and then clicking the button. The criteria list data i s saved in a You can then access the criteria list at any time by opening the Current drop-down list and choosing the name of the saved criteria list.
Filtering Objects by Location
Notice the X Y and Z pull-down lists just below the main Select Filter drop-down list in the Object Selection Filters dialog box: these lists become accessible when you select a criteria that describes a geometry or a coordinate (such as an arc’s radius or center point). You can use these lists to define filter selections even more
specifically using greater than (» less than «) equal to (=) or not equal to (!=) comparisons (called relational operators).
For example suppose you want to grab all the circles whose radii are greater than 4.0 units. To do this choose Circle Radius from the Select Filter drop-up list. Then in the X list, select the >. Enter 4.0 in the input box to the right of the X list and click Add to List. You see the item Circle Radius> 4.0000 added to the list box at the top of the dialog box. You used the> to indicate a circle radius greater than 4.0 units.
Creating Complex Selection Sets
There will be times when you want to create a very specific filter list. For instance say you need to filter out all the door blocks on the layer Floor2 and all arcs with a radius equal to 1. To do this, you use the grouping operators found at the bottom of ,” the Select Filterdrop-down list. You’ll need to build a list as follows
** Begin OR
** Eegin AND
Entity = Bl~ck
Layer – Floor2
** End A~D
** Begin AND
Entity = Arc
Arc Radius z 1.0000
** End AND
** End OR:
Notice that the Begin and End operators are balanced that is for every Begin OR or Begin AND there is an End OR or an End AND.This list may look rather simple, but it can get confusing-mostly because of the way you normally think of the terms AND and OR If criteria are bounded by the AND grouping operators, then the objects must fulfill both criteria before they are selected. If criteria are bounded by the OR grouping operators, then the objects fulfilling either criteria will be selected.
Here are the steps to build the list shown just above.
1. In the Select Filter drop-down list choose **Begin OR and click Add to List”Then do the same for **Begin AND.
2. Click Block in the Select Filter drop-down list, and then click Add to List.
3. For the laver dick Layer from the select Filter drop-down list: Then click Select, choose the layer name, and dick Add to List.
4. In the Select Filter drop-down list, choose “””End ANDand dick Add to List. Then do the same for *”‘Beg; nAND.
5. Select Arc from the Select Filter drop-down list and click Add to List.
6. Select Arc Radius from the Select Filter list, and enter 1.0 in the input box next to the X drop-down list. Be sure the equal sign (=) shows in the X dropdown list and then click Add to List.
7. Choose **End ANDand click Add to List. Then do the same for **End OR. If you make an error in any of the above steps, just highlight the item, select an. item to replace it, and dick the Substitute button instead of theAdd to List button. If you only need to change a value, dick Edit Item near the center of the dialog box .
The Filter command offers a lot of power in isolating specific types of objects but in many situations, you may not need such an elaborate tool. The Q select command can filter your selection based on the object properties which are more common filter criteria. To access the Q select command choose Tools> Quick Select or right-click the drawing area when no command is active and choose Quick Select from the popup menu. The Quick Select dialog box appears. Quick Select is also offered as an option on a few dialog boxes. Try using the Wblock command again this time using the Quick Select option offered in its dialog box.
Finding Geometry with the Calculator
Another useful AutoCAD tool is the Geometry Calculator. Like most calculators it adds, subtracts, divides and multiplies. If you enter an arithmetic expression such as 1 + 2 the calculator returns 3. This is useful for doing math on the fly but the Calculator does much more than arithmetic as you will see in the next examples.
Finding the Mid point between Two Points
One of the most common questions heard from AutoCAD users is, “How can I locate a point midway between two objects?” You can draw a construction line between the two objects, and then use the Midpoint override to select the midpoint of the construction ljne. The Calculator offers another method that doesn’t require drawing additional objects.
In the following exercise, you start a line midway be~een the center of an arc and the endpoint of a line. Draw a line and an arc and try this out.
1. Start the Line command, and at the From poi nt prompt, type Cal.J.
2. At the» Expressi on: prompt, enter (end + cen)/2.J.
3. At the» Select enti ty for END snap: prompt, the cursor turns into a square. Place the square on the endpoint of a line and click it.
4. At the» Select enti ty fo r CEN snap: prompt, click an arc. The line starts midway between the arc’s center and the endpoint of the line.
do know that the distance is the sum of two values-unfortunately one value is in feet and the other is in inches. Usually in this situation you would have to reach for pen and paper (or if you’ve got one a feet-and-inches calculator) then figure out the distance and then return to your computer to finish the task. AutoCAD’s Geometry Calculator puts an end to this runaround.
The following shows you what to do if you want to move a set of objects a distance that is the sum of 12′ 6-5/8″ and 115-3/4”’.
1. Issue the Move command select objects and pick a base point.
2. At the Second poi nt: prompt start the Calculator.
3. At the» Express on: prompt enter [@12’6″+ 115-3/4″ < 45]. Then press .J and the objects move into place at the proper distance.
You must always enter an inch symbol (0) when indicating inches in the Calculator
In this example you are mixing inches and feet, which under normal circumstances is a time-consuming calculation. Notice that the feet-and-inches format follows the standard AutoCAD syntax (no space between the feet and inch values).
The coordinate value in square brackets can have any number of operators and values as in the following:
[@4 * (22 + 15) – (23.3 / 12) + 1 < 13 + 17]
This expression demonstrates that you can also apply operators to angle values.
Guidelines for Working with the Calculator
You may be noticing some patterns in the way expressions are formatted for the Calculator. Here are some guidelines to remember:
• Coordinates are enclosed in square brackets.
• Nested or grouped expressions are enclosed in parentheses. .
• Operators are placed between values, as in simple math equations.
• Object snaps can be used in place of coordinate values.
Table 12.2 lists all the operators and functions available in the Calculator. You may want to experiment with these other functions on your own.
You may want to experiment further with Paper Space to become more familiar with it. Try the following exercise. In it you will add two more viewports using the View >Viewports (Floating) options (Mview and Copy commands). In the process you’ll find that editing Paper Space views requires frequent shifts from Model Space to Paper Space and back.
1.Open the Xrefl file you used for the earlier Paper Space exercise.
2.If you aren’t already in Paper Space, click the Layout! tab and make sure
3.PAPER appears in the status bar.
4.Stretch the lower viewport so that it occupies the. lower-right third of the
screen (see the top image of Figure 12.42).
5.Switch to Floating Model Space and click the lower viewport. Pan the view so the entire stair is displayed.
6.Return to Paper Space to create a new viewport.
7.Choose View :> Viewports :> New Viewport, or type vports.J.
8.n the Viewports dialog box, make sure the New Viewports tab is selected . and select Single from the list. ..
9.Click OK, then click the lower-left comer of the screen.
10.At the Other corner prompt, size the viewport so that it is similar to the viewport on the right, as shown in the bottom image of Figure 12.42.
11.Click the PAPER button in the status bar to go to Floating Model Space then .
click the lower-left viewport. .
12.Type Regen.J. Notice that only the current viewport regenerates.
13.Use the Zoom and Pan commands to display the stairway at the far left of the floor plan.
14.Return to Paper Space and copy the new viewport to the right.
15.Return to Floating Model Space and use the Realtime Pan tool to pan the view in the new viewport to display the stairway to the far right of the floor plan. Notice that when you use the Realtime Pan tool, you can pan across the entire AutoCAD window; you’re not limited to panning just inside the viewport area. You can also use the scroll bar to pan the active viewport.
16. Return to Paper Space to resize the viewports to display only the stairs, as in Figure 12.43.