CADvocate
FEBRUARY, 1997
Table Of Contents
Editorial
Our Next Meeting
Welcome New Members
Christmas Social Review
President's Message
CAD Productivity - Block Symbol Library
Tips'n'Tricks - Trimming Donuts
Programming with AutoLISP
CAD Quiz
EDITORIAL
Hello, and welcome to the first edition of the MUGONS Newsletter for 1997. As you may have noticed, the MUGONS Newsletter is coming to you more frequently. We have been able to establish a format and system which help get the Newsletter to you quickly a
nd more often. We would like to publish the Newsletter monthly, but to do that, we need more members to contribute. If we can get every member to contribute just one article, we can easily produce twelve informative and entertaining issues during the year
. Your article can be a LISP routine, a tip'n'trick, a success story using CAD, or even a brief biography of yourself and how you use your CAD package. You can submit your article at any meeting to Murray Clack (or any of the executive members) and if p
ossible, provide it on diskette in ASCII format. You can also fax it to any of the executive members (see the last page for fax numbers) Don't worry about spelling or sentence structure, we have enough proofreaders to help "iron out any wrinkles." If yo
u really don't have time to write an article yourself, pass along your ideas for articles you'd like to see, and we'll try to put them together.
OUR NEXT MEETING
Our next meeting will be held on February 20, 1997 at 6:30 p.m. held in the AV Room located at the Nova Scotia Community College (N.S.C.C.) in Halifax, on Bell Road. Paid members are reminded to bring their sharware diskette for an update of new and usef
ul routines. Some of which will be demo'd at the next meeting.
WELCOME NEW MEMBERS
We would like to welcome some new members to MUGONS, Bruce Algee of Chebucto Engineering, Gary Neate of the Halifax Regional Municipality, and the return of Larry Wagner of L. Wagner Engineering. If you wish to join MUGONS, a regular memberships is $35.0
0 per year, ($15.00 for students). For $85.00, a corporate membership entitles all employees of a company to enjoy the benefits of MUGONS.
CHRISTMAS SOCIAL REVIEW
MUGONS recently held its Christmas social with an exceptional turnout. Everyone convened in the CAD Lab at the Community College where there was lots of food and drink, and door prizes were even given away. In fact, it almost felt like Halloween because
an eerie situation took place. MUGONS President, Darrell MacDonald, was awarding the prizes by selecting names of attendees from a hat. Darrell stated, "I'm eligible to win because I paid my membership dues, right?" Sure enough, he drew his own name. Aft
erward, Murray Clack promptly yelled out, "Hey Darrell, draw my name next!" Believe it or not, he drew Murray's name. Things got a little quiet then. Darrell and Murray both won a $25.00 gift certificate to East Side Mario's, a very popular Italian resta
urant located on Beford Row. Other winners include Mary Hellstrom, Doriano Sablone, and Tony Beck, all of whom won the very popular MUGONS coffee mug. Overall, it was a great night and everyone present definitely had the Christmas spirit.
PRESIDENT'S MESSAGE- by Darrell MacDonald
We on your MUGONS executive committee are looking forward in 1997 to many more very informative sessions, as we had in 1996. You may have noticed in our new logo that our purpose is stated as, "Sharing Insights to Maximize Proficiency." The word "sharing"
being the operative term. We welcome input from any who may have experience with a CAD package, a general computer utility, or an add-on to a CAD package. Have you used an AutoCAD add-on like Arch-T by Ketiv Technologies or Softdesk's AutoArchitect? Let
us know what you've found. Have you any experience with CAD packages other than AutoCAD, such as Minicad, Archicad or Allplan? If so, out membership would truly enjoy hearing your thoughts. What do you think of Autodesk's acquisition of Softdesk? Will it
inhibit competition? Let us know your opinion and take the word "sharing" and make it work for all of us. Any comments could be faxed to any of the executive committee members listed on the last page of this newsletter or, better still, come to our meetin
gs and enhance our discussions with your insights.
CAD PRODUCTIVITY - Block Symbol Library
How many times have you drawn the same symbol over and over again? How many times has the look of your drawing conflicted with a co-worker's drawing on the same job? After copying or moving a symbol, how many times have you discovered that some entities
are missing only after the drawing has been plotted? Even if it has happened only once, it is time to consider establishing a block symbol library. Even if a symbol is extremely simple, like an electrical outlet, having it established as a block will s
ave countless hours of drafting time. Blocks also keep a uniform look amongst the drawings on a project. By establishing a block library, you and your co-workers won't have to worry about conflicting drafting practices. Even with a simple electrical out
let, one person may make the circle bigger or smaller, the projection lines may be longer, shorter or spaced apart differently. Taking these factors into consideration, a final plotted drawing with non-uniform looking symbols can cause confusion for the
client, and embarrassment for the company who designed the job. One of the best reasons for using blocks is the ease of changing its properties globally. Let's say you wish to change the radius of the circle because it's just a tad too big, you can glob
ally change the properties of the symbol simply by redefining the block after you've made the necessary changes to an exploded version. Blocks also help maintain layer, colour and linetype consistency. Blocks that contain attributes are yet another great
time saver. One good example of a block with attributes is your company title-sheet. Having inconsistencies with drafting symbols is bad enough, but having inconsistencies in the company title-sheet will be totally unacceptable. However, creating a co
mpany title-sheet with attributes will not only maintain consistency, but speed up productivity when inserting and/or editing the block. Here are some other benefits to using blocks [with attributes]: 1. If you must copy or move a symbol, you only have t
o select one entity. 2. Attribute text will always maintain the same height, style, justification, position and pen thickness. 3. Blocks take up less room (memory wise) in the drawing. 4. Once again, blocks help maintain consistency when two or more peopl
e/consultants are working on the same project. Blocks can also help a sub-consultant with whom you are working on a project. Instead of letting a sub-consultant redraw dozens (if not hundreds) of symbols simply to match your standard, you can supply the
sub-consultant with a diskette containing all your standard symbols, thus preserving precious drafting time. Once you have taken the time to establish a block symbol library, you will be amazed at how much your productivity increases when compiling desi
gn drawings. The major benefit to establishing a block library is that you only have to do it once.
TIPS'n'TRICKS - Trimming Donuts
Did you know that it is possible to trim an AutoCAD donut? Most people use donuts to create solid circles or to draw filled in rings (ergo: donut). There are times when you need a symbol that contains circles where only portions of it are filled in. One
example is a borehole symbol used in the Civil/Surveying disciplines. Trouble is, people either offset a circle numerous times and trim the excess, or they use an intense hatch pattern (Continued...)
which takes longer to perform a "regen" and hogs a lot of memory. Not to mention both of these methods take away precious productivity time. Try this instead. First, draw a donut with an inner diameter of zero and an outer diameter of your choice, and t
hen draw two lines crossing each other at the center point of the donut with a desired length, see figure 1. Second, initiate the TRIM command and select the two cross lines as cutting edges, and trim back two quadrants of the donut opposite each other, s
ee figure 2. Third, initiate the CIRCLE command, pick the center of one of the donut quadrants [using the center osnap] as a base point, and then enter a diameter for the circle matching that of the donut, see figure 3. That's it! Notice how the circle
helps define the symbols shape. Experiment to see what other shapes you can produce (see additional examples as shown). There are some basic guidelines to remember: 1. Make sure your cutting edges cross over the center point of the donut. 2. The cuttin
g edges can be at any angle, not just 90° . 3. The inner diameter of the donut does not have to be a value of "zero." Now, save this symbol as a drawing file and place it in your block library.
PROGRAMMING WITH AutoLISP
This issue, we begin explaining the mysteries of AutoLISP programming by starting with the basics. First of all, there are some basic rules when it comes to writing an AutoLISP routine: 1. Every expression has an opening and closing parenthesis. 2. Every
expression has a function name. 3. Every expression gets evaluated and returns a result.
Again, all expressions have a value, or a result, which AutoLISP determines by a process called "evaluation" in which it reads from left to right and expects the first element after the open parenthesis to be one of AutoLISP's many "functions." The functi
on found gives specific instructions on what is to be done with what comes next. For example, in the following expression AutoLISP finds the function "setvar" immediately after the open parenthesis.
(setvar "osmode" 0)
It then goes on to evaluate the "arguments" to the function based on the purpose of the function. In this case, the "osmode" system variable is "set" to 0. Functions can be "nested" to create more complex expressions.
Consider the following:
(setq OS (getvar "osmode"))
AutoLISP finds the function "setq" after the first parenthesis and then encounters two arguments. The first being the name of the defined variable which the "setq" function is to use as a storage place for the result of the next argument. The second arg
ument to the "setq" function is itself an expression to be evaluated to yield a result. This expression uses the "getvar" function with one argument. AutoLISP gets the current value of the "osmode" system variable and returns it's value to the "setq" func
tion which then saves it to the user defined variable called "OS." Simple isn't it? One trick to AutoLISP programming is to know all of the functions that are available and how they work. But, there are literally hundreds of functions available. One sug
gestion would be to refer to trade magazines like CADalyst or CADENCE which often have monthly articles on AutoLISP programming. There are also text books like, "AutoLISP in Plain English", by George Head, and "Maximizing AutoLISP" by New Riders Publishe
rs, Both of which come highly recommended. Feel free to check out what books are available at the MUGONS library
CAD QUIZ - Test Your Knowledge
1. You can create offsets with the offset command by:
a) PICKING SPECIFIED POINTS
b) ENTERING SPECIFIED DISTANCE
c) A & B
d) NONE OF THE ABOVE
2. Text can be displayed as boxes by entering the system variable:
a) BOXTEXT
b) QTEXT
c) STYLE
d) ALL OF THE ABOVE
Answers 1C, 2B
DALTECH
CAD/CAM CENTRE Courses
AutoCAD R13 Level 2 - February 11, 12, 13 & 14
AutoCAD R13 Level 1 - February 18, 19, 20, 25 & 26
Contact Clara Sarson @ (902) 420-7764 or FAX (902) 420-8380
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