192
AutoCAD and Its Applications—Advanced
Solid Model History Solid Model History
AutoCAD can automatically record a history of a composite solid model’s construction.
A composite solid is created by a Boolean operation or by using the d
SOLIDEDIT
command.
T
The retention of a composite solid’s history is controlled by the
History
property setting in
y
the
Solid History
category of the
y Properties
palette. By default, the
History
property is set to
y
None. Refer to Figure 8-1. This means that the history is not saved and that edges, vertices,
and faces of solids can be directly edited. If the
History
property in the
y Properties
palette is
set to Record, the solid history is “recorded,” or retained. This allows you to work with the
geometry used in modeling operations to create the composite solid. Depending on your
modeling preferences, it is generally a good idea to have the history recorded. Then, at any
time, you can graphically display all of the geometry that was used to create the model.
The retention of solid model history for newly created composite solids is controlled
by the
SOLIDHIST
system variable. By default, the
T SOLIDHIST
system variable is set to
T
0.
This means that all new solids have their
History
property set to
y None
and solid history is
not recorded. If the
SOLIDHIST
system variable is set to a value of
T
1, all new solids have
their
History
property set to
y Record
and solid history is preserved. With either setting of
the system variable,
0
(None) or
1
(Record), the
Properties
palette can be used to change
the setting for individual solids. The current setting of the
SOLIDHIST
system variable is
T
indicated by the
Solid History
button located in the
Primitive
panel of the
Solid
tab on the
ribbon. See Figure 8-2. With a default setting of
0
(None), the
Solid History
button has a
white background. Picking this button when it has a white background changes the back-
ground color to blue and sets the
SOLIDHIST
system variable to
T 1
(Record).
To view the graphic history of a composite solid, set the
Show History
property in the
y
Properties
palette to Yes. All of the geometry used to construct the model is displayed.
If the
SHOWHIST
system variable is set to 0, the
0 Show History
property is set to
y No
for all
solids and cannot be changed. If this system variable is set to 2, the
Show History
property
y
is set to
Yes
for all solids and cannot be changed. A
SHOWHIST
setting of
1
allows the
Show History
property to be individually set for each solid. This is the default setting.
y
An example of showing the history on a composite solid is provided in Figure 8-3.
In Figure 8-3A, the model appears in its current edited format. The
History
property
setting was initially set to
Record
before performing two Boolean subtraction opera-
tions. The
Show History
property is currently set to
No
and the
Conceptual
visual style
Figure 8-1.
The
Properties
palette can be used
to change many of
the properties of a
solid.
Type of
object
selected
Selected
property
to modify
Category
History
settings
Properties
within the
category