194
AutoCAD and Its Applications—Advanced
is set current. In Figure 8-3B, the
Show History
property is set to Yes. Isolines have
also been turned on. You can see the geometry that was used in the Boolean subtrac-
tion operations. Using subobject editing techniques, the individual geometry can be
selected and edited. In Figure 8-3C, the sphere (the subtracted object) is selected while
pressing the
[Ctrl]
key. Selecting the sphere in this manner selects the solid primitive
subobject and displays a grip tool for editing the subobject. Using grip tools for editing
3D objects is introduced later in this chapter. Subobject editing is discussed in detail
in Chapter 11.
PROFESSIONAL P O TIP P PROF RO FE S SS I O NA A L T I NA AL T TI P P
If the
Show History
property is set to
Yes
to display the components of
the composite solid, as seen in Figure 8-3, the components will appear
when the drawing is plotted. Be sure to set the
Show History
property
to
No
before you print or plot.
Selection Cycling Selection Cycling
When selecting objects that are on top of each other or occupy the same space,
selection cycling is the preferred method to select one of the objects. When editing, g
you may need to erase, move, or copy one of the objects that overlap in order to select
the correct object. The
[Shift]
key and space bar can be pressed at the same time to cycle
through objects at a pick point. When you need to cycle through objects:
1. At the “select objects” prompt, hold down the
[Shift]
key and space bar, then click
to select the object you want.
2. Keep clicking until the object you want to select is highlighted.
3. Press the
[Enter]
key.
You can use the
SELECTIONCYCLING
system variable to turn on selection cycling
instead of using the
[Shift]
key and space bar. The
Selection Cycling
button on the
status bar is used for toggling selection cycling. There are three settings for the system
variable:
• Off (0).
• On, but the list dialog box does not display (1).
• On and the list dialog box displays the selected objects that can be cycled
through (2).
It is recommended that you turn on selection cycling. With selection cycling turned
on, you can cycle and select the faces that may overlap one another.
In Figure 8-4, the two 3D objects occupy the same space. The tapered 3D object
needs to be moved up using the
3DMOVE
command. Turn on selection cycling. When
you select the tapered object, the
Selection
dialog box lists the objects overlapping at
the pick point. Select which object you want to work with by picking it in the dialog
box. As your cursor is over an object in the list, the object is highlighted in the drawing
area.
PROFESSIONAL P O TIP P PROF OFES S I O O RO FE S SS I O N A L T I NA NA AL T TI P P
If multiple 3D objects occupy the same space, selection cycling gives
you the ability to select the correct object needed to complete the edit.
SELECTIONCYCLING
Ribbon
SELECTIONCYCLING
Toolbar
Status Bar
Selection Cycling