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SUPPLEMENTALMATERIALS

Copyright by Goodheart-Willcox Co., Inc. Object Selection Filters, page �

AutoCADand Its Applications

B A S I C SStudent CDStudent CD

Using Filters to Create a Selection SetThe FILTER command is used to create a list of property criteria that must

be met in order for a specific object to be selected. Filter lists can be created for use at any time. These filter lists are accessed at any Select object: prompt.

The FILTER command is accessed by entering FI or FILTER. This opens the Object Selection Filters dialog box, Figure OS-1. The FILTER command can also be used trans-parently by entering ‘FILTER at the Select object: prompt.

The three major areas of the Object Selection Filters dialog box are the list box, the Select Filter area, and the Named Filters area. The list box is where the current filter list data is displayed, the Select Filter area is used to specify filter criteria, and the Named Filters area is used to save filters for future use.

FILTERPull-Down MenuFilter > FI

Pick to edit itemin filter list

Pick to delete ahighlighted item

from the list

Pick to erase allitems in filter

List of filtered items

Filter options

Pick to additem to filter

Enter name fornew filter

Pick to savea new filter

Figure OS-1. The Object Selection Filters dialog box.





Entering Filter DataThe Select Filter area of the Object Selection Filters dialog box is where filter

data are entered. The drop-down list and edit boxes can be used to enter the values for the filters. Objects in a drawing can even be selected to develop a filter.

The three edit boxes correspond to X, Y, and Z point coordinates. They are enabled as needed for entering different types of filter information. When the filter drop-down list reads Arc, it refers to an object type. Since no further infor-mation is required about the object type, the edit boxes are all disabled. Setting the filter to Arc Center enables all three edit boxes, which are used to define the center point. When Arc Radius is selected, only the top edit box is enabled because only a single value is required. An example of each of these situations is shown in Figure OS-2.

For many filter specifications, such as layer, linetype, and color, the Select… button is enabled. When picked, this button displays the appropriate dialog box for showing the available options. For example, if Color is the specified filter, the Select… button displays the standard Select Color dialog box.

Once the desired filter and value(s) are specified, you must add these data to the list. Pick the Add to List button to add the new item to the existing filter list. The list at the top of the dialog box is updated.

Object FilterEdit boxes deactivated

Point FilterAll three edit boxes active

Distance/Length FilterOne edit box active

Figure OS-2. This shows examples of filter items with the X:, Y:, and Z: edit boxes enabled as needed.





To use an existing object as a basis for a filter list, pick the Add Selected Object button. This temporarily closes the Object Selection Filters dialog box and gives you a Select object: prompt. Once an object is selected, you are returned to the dialog box. The information from the selected object is placed in the filter list. Since you may not need all of the filter list specifications that result from picking an object, the filter list can now be edited as needed.

To remove an item from the filter list, highlight it and pick the Delete button. To clear the entire list and start over, pick the Clear List button. To edit an item in the list, highlight the item and pick the Edit Item button. Editing the filter list is discussed in more detail later in this chapter.

To introduce applications of selection filters, the following example creates a simple filter list that selects only circle objects. Type FI to display the Object Selection Filters dialog box. In the Select Filter area, pick the drop-down list to see the selection filter options. Select Circle from this list. To add this specifica-tion to the filter list, pick the Add to List button. The list box now displays this selection criteria as Object = Circle. This shows that only circle objects will be selected. See Figure OS-3. To use the selection filter, pick the Apply button. The dialog box is closed, and the following prompt is issued:

Selectionset criteria

Pick objecttype to beselected

Pick to addto list

Figure OS-3. Setting the filter so that only circles are selected.





Applying filter to selection.Select objects: (use window, crossing, fence, or ALL to select objects)

The prompt tells you that the filter is active. In Figure OS-4, a selection window is created around a group of lines, arcs, and circles. Because the filter is set to allow only circle objects, all other object types are filtered out of the selection. AutoCAD reports the number of objects found and the number filtered out (not selected):

�� found 8 were filtered out.Select objects:

To exit the filtered selection, press [Enter] at the Select objects: prompt. The message Exiting filtered selection appears on the command line and the selected objects are displayed with grips. If the FILTER command was entered trans-parently, pressing [Enter] displays the message Resuming (command) command. That command’s normal Select objects: prompt is displayed.

Selectionwindow

Figure OS-4. All objects are filtered out except for the circles.





Filter lists can be expanded to select only objects with specific properties. The next example creates a filter list that selects only line objects that have a CENTER linetype. The steps are: 1. Enter the FILTER command and clear the list box by picking the Clear

List button. This starts a new filter list. 2. From the drop-down list in the Select Filter area, select Line, then pick

the Add to List button. This adds the filter Object = Line to the list box. 3. Select Linetype in the drop-down list and then pick the Select… button

to display the Select Linetype(s) dialog box. Select the CENTER linetype and pick the OK button.

4. Pick the Add to List button. The Object Selection Filters dialog box should appear as shown in Figure OS-5.By adding additional filters to the filter list, a filter can be extremely specific

when needed. Filters for a specific location or a specific text string can be useful when selecting items in very large, complex drawings.

Press Select… to displaylinetypes available

Figure OS-5. Line objects with CENTER linetype will be selected by this filter.





Working with Relative OperatorsThe term relative operator refers to functions that determine the relationship

between data items. These relationships include equality, inequality, greater than, less than, and combinations such as greater than or equal to and less than or equal to. Each of the three edit boxes in the Select Filter area are preceded by a rela-tive operator drop-down list. By default, the operator is “equal to” when the list is enabled. An appropriate relative operator can be selected for each data field.

For example, a relative operator can be used to select all arcs that have a radius of 2.5 or greater. To do this, the filter specification is Arc Radius with 2.5 entered in the enabled edit box. Then, select the greater than or equal to symbol (>=) in the relative operator drop-down list. See Figure OS-6. The following chart shows the relative operator functions:

Symbol Meaning= Equal to!= Not equal to< Less than

<= Less than or equal to> Greater than>= Greater than or equal to× Equal to any value

Enter settingvalue

Pick after editingan item from the

filter list

Relative operatordrop-down list

Pick to selectan object with

propertiesto be filtered

Figure OS-6. The greater-than-or-equal-to filtering option.





Editing the Filter ListEditing capabilities are provided that allow you to modify and delete filter

list items. If you accidentally enter an incorrect filter specification, you can easily correct it using these steps. 1. Highlight the item in the filter list that you need to edit and pick the Edit

Item button. The values for the selected specification are then entered in the Select Filter area and can be freely edited.

2. Change the values as necessary. 3. Pick the Substitute button when finished. The edited filter specification

is substituted for the highlighted item. Be sure to pick Substitute and not Add to List; otherwise, you end up with two different values for the same filter specification in the filter list.To remove an item from the filter list, highlight it and select the Delete

button. Only one filter specification can be deleted at a time using this method. If you need to remove all of the current specifications and start over, pick the Clear List button.

Creating Named FiltersThe most powerful feature of CAD is being able to benefit from work you have

already done. By reusing previous work instead of repeating the work to produce duplicate results, you increase your efficiency and overall productivity levels.

Complex filter lists can be time-consuming to develop. However, AutoCAD allows you to name and save filter lists. Then, you can recall the lists for future use. The Named Filters area of the Object Selection Filters dialog box is used to create and manage these lists.

When you have created a filter list that you plan to use again, it should be named and saved. When the filter list is completed and tested, follow these steps to name and save the list. 1. Pick in the edit box to the right of the Save As: button. 2. Type a short, descriptive name in the edit box. The name for a filter list

can be up to 18 characters in length. These named filter lists are stored in a file named filter.nfl and are available until deleted.

3. Pick the Save As: button to save the named filter.


Copyright by Goodheart-Willcox Co., Inc. Object Selection Filters, page 8



To delete a saved filter list, make it current by picking the filter name in the Current: drop-down list. Then, pick the Delete Current Filter List button.

Using Filters on a DrawingFilters can increase productivity, but you must learn to recognize situations

when they can be used. Imagine that you have just created the flowchart in Figure OS-7. You are then asked to change all of the text inside the flowchart to a new layer and color for plotting considerations. You could use the Properties window and individually select each word on the chart, but you decide to use the FILTER command to make the job easier. Access the command to open the Object Selection Filters dialog box, and follow these steps.

Figure OS-7. Original flowchart requiring modification.





1. Pick the Add Selected Object button. The drawing returns with a Select object: prompt. Pick a text element within any one of the boxes.

2. The dialog box returns and displays the characteristics of the text you picked. Highlight an item such as Text Position and pick the Delete button. See Figure OS-8. This filter is not needed because it limits the selection to text in that exact location.

3. Enter a filter name, such as TEXT, in the Save As: text box and then pick the Save As: button. TEXT becomes the current filter name.

4. Pick the Apply button. The drawing returns and you are prompted:

Select object:Applying filter to selection.Select objects: ALL↵Select objects: Specify opposite corner: �� found�0� were filtered out.(the text within the flowchart is now highlighted)Select objects: ↵Exiting filter selection.Command:

5. All text is selected and displayed with grips. 6. Use the Properties window or other editing method to modify the

selected text. The revised flowchart is shown in Figure OS-9.

Figure OS-8. Deleting selection filters that are too specific.


Copyright by Goodheart-Willcox Co., Inc. Object Selection Filters, page �0



Figure OS-9. Revised flowchart. All text in the flowchart is now displayed in color.

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