Fit the Hatch on the Corner
by Alireza Parsai,
April 10, 2003
Sometimes you may need to create a hatch that passes through one
of the corners of the enclosing area. There is a simple solution
to this problem: Set the SNAPBASE system variable to a
proper value.
SNAPBASE indicates the location for the snap base point. You can
change the value of SNAPBASE system variable by changing the X
base and Y base contents in Drafting Settings dialog box [Figure
1]. To view this dialog box, right-click on SNAP or GRID button
on status bar and then select Settings.
Figure 1
You can also set this variable by typing its name in command
line and assign a new value. For example:
Command: snapbase
Enter new value for SNAPBASE <0.0000,0.0000>: 4.67,1.31
The SNAPBASE alters the base point for Snap and Grid. It also
affects the behavior of BHATCH command in creating hatches. Here
are two typical examples to illustrate the usages of this system
variable.
Example 1
You want to draw a 4 by 5 rectangle. The lower left corner of
the rectangle is located at 9.54,2.43. Both Snap and Grid are
enabled and their distances are set to 1.
Solution:
-
Set the SNAPBASE to 9.54,2.43.
-
Invoke RECTANG command.
-
Move the cursor till you view 9.54,2.43 as the current location
in coordinate display [Figure 2].
Figure 2
-
Click.
-
Move the cursor 4 units to the left and 5 units up.
-
Click.
Example 2
You would like to hatch the area enclosed inside the rectangle
shown in figure 3. The pattern that you will use is: User
defined, Angle = 45 degrees, and Spacing = 0.5 units.
Figure 3
Solution:
If the SNAPBASE is equal to 0.0,0.0 the result will be similar
to the following figure:
Figure 4
Now set the SNAPBASE to 4.25,3.75. The result is shown in the
following figure. Note that one of the hatch lines passes
through the lower left corner of the square.
Figure 5
A Useful Program
I have written a simple program to set the SNAPBASE by selecting
a point in the drawing area. The program name is setsb.lsp and
defines a command called SETSB. Click
here to download the file.
If you are not familiar with loading applications into AutoCAD
please read my article
Loading Applications into AutoCAD 2002.
About the Author
Alireza Parsai is the founder of cadpanel.com. He is a
mechanical engineer with more than 12 years experience with
AutoCAD. Alireza is an Autodesk Authorized Author, the AutoCAD
consultant for Al Khawarizmi Institute, a contributing editor
for Augiworld magazine, a writer for CAD Digest, an instructor
for AUGI Training Program, and an elected speaker for Autodesk
University 2002. He has written 7 books in Farsi, 3 booklets in
English, and more than 30 articles for different magazines and
newsletters. You can reach him at
alireza.parsai@cadpanel.com or visit his website
www.cadpanel.com.
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