Graphics Programs Reference
In-Depth Information
parameters, the parameters change to allow input. If they're selected, you're prompted
for those parameters after you click OK to close the dialog box. With all three Specify
On-Screen check boxes cleared, the Xref is inserted in the drawing using the settings indi-
cated in the dialog box.
Attachment
Tells AutoCAD to include other Xref attachments that are nested in the
selected file.
Overlay
Tells AutoCAD to ignore other Xref attachments that are nested in the selected file.
This avoids multiple attachments of other files and eliminates the possibility of circular refer-
ences (referencing the current file into itself through another file).
Details
Displays or hides the path information for the selected Xref file.
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In addition to those mentioned, there are two other options that are used in Xref editing:
Visretain
Instructs AutoCAD to remember any layer color or visibility settings of Xrefs
from one editing session to the next. In the standard AutoCAD settings, this option is on by
default. Visretain has two settings: 0 - Off and 1 - On.
XEdit System Variable
Allows editing the drawing in place. XEdit has two settings: 0 - No
and 1 - Yes.
Clipping xref Views and Improving Performance
Xrefs are frequently used to import large drawings for reference or backgrounds. Multiple
Xrefs, such as a floor plan, column grid layout, and site-plan drawing, might be combined
into one file. One drawback to multiple Xrefs in earlier releases of AutoCAD was that the
entire Xref was loaded into memory even if only a small portion of it was used for the final
printed output. For computers with limited resources, multiple Xrefs could slow the system
to a crawl.
AutoCAD offers two tools that help make display and memory use more efficient when using
Xrefs: the Xclip command and the Demand Load feature.
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The Xclip command lets you clip the display of an Xref or a block to any shape you want, as
shown in Figure 7.18. For example, you might want to display only an L-shaped portion of a
floor plan to be part of your current drawing. Xclip lets you define such a view. To access the
command, type
XCLIP
↵.
You can clip blocks and multiple Xrefs as well. You can also specify a front and back clipping
distance so that the visibility of objects in 3D space can be controlled. You can define a clip area
by using polylines or spline curves, although curve-fitted polylines revert to decurved polylines.
(See Chapter 17 for more on polylines and spline curves.)
