February 26, 2003 DBUG Meeting
Hosted by Mike Smith

Notes Regarding DataCAD 11

Mark Madura was kind enough to pay a visit to our meeting last night
and tell us about the implementation and implications of a
double-precision database vs. a single-precision database. I do not
know enough about programming data structures to give you any
technical data, but with considerable programming expertise of the
DataCAD LLC crew I have to believe that if they say the data is
stored at a certain size (in KB) then that's just the way it is.

Single-Precision ================

The current single-precision
database is "effectively" accurate out to 7 decimal places,
including both the left and right side of the decimal, like:
              246.0174
               11.98245
        1,498,234
          453,215.5

Because all data points are referenced from the
absolute zero point of the drawing file, inaccuracies creep in the
farther you go from that point.  This can be especially true when
dealing with angles, since angles are stored and calculated in
radians, then converted to degrees.  Depending on the distance from
the absolute zero point the radians may first be rounded, then
further rounding occurs when converting to degrees.

Double Precision
================

Double-precision does not mean the database is twice as accurate.
It is actually something like 10,000 times as accurate!  To
illustrate this Mark said to imagine a single-precision database as
a square box drawn on your screen with each side 260 feet long.  Now
imagine a double-precision database is a square box with each side
493,000 MILES long!!  Yes, miles!

The database is "effectively" accurate out to 14 decimal places
(hence, I assume, the "double" accuracy), including both the left
and right side of the decimal, like:

              246.01748376194
               11.982457639085
        1,498,234.0745213
          453,215.57832567
    2,591,482,958.8930

Precision in DataCAD 11
=======================

Depending on the programming progress the initial release of DataCAD
11 may be issued with the same single-precision database, with a
free double-precision update to be issued sometime afterward.  If
things have advanced enough we might see double-precision in the
initial release.

When a pre-version 11 file is opened in DataCAD 11 it will
automatically inherit (via an on-the-fly conversion when the file is
first opened) double-precision accuracy, effectively "cleaning up"
and optimizing the file.

Don't ask me the mathematical specifics (because I don't know), but
we were assured that a double-precision database would just about
double the file sizes, even with optimizations in text, hatching,
etc.  However, DataCAD LLC is looking into using a file compression
algorithm that would squeeze the file size down to 1/10th the size
on disk.  That means that a 2MB file might be only 200K on your hard
drive.  That file, when opened, would expand to its full size of 2MB
in memory (RAM), but would still be only 200K on the hard drive.

And no, there is no way to add a "toggle" to turn the
double-precision on and off.  Double-precision requires hard-coding
every aspect of DataCAD to accept the more precise data.

File Format
===========

It appears that with double-precision, plus all the new parametric
features being added, DataCAD 11 will indeed have a new database and
file format.  Rather than a .DC5 file it will have some other, as
yet undecided, file extension.

Although it is programmatically possible to create a "conversion"
utility in DataCAD to "Save As" a .DC5 file, this is not planned,
due to the man-hours of programming that this would require.  As
Mark noted, when you are a small software developer you have to pick
your priorities. Moving DataCAD forward, rather than backward, is
more important to the life of the product at this time.  That means
that all pre-version 11 files will be able to be opened in DataCAD
11, but DataCAD 11 files will not be able to be opened by versions
10, 9, 8, etc.  Mark assured us this is not an AutoDesk-like ploy to
force users to upgrade.  It's an inevitable matter of economics.

As a workaround you could Export a drawing as a .DWG or .DXF file and
then open it in earlier DataCAD versions, but of course you would loose
some of the DataCAD-specific data, including Multi-Scale Plotting
layouts and GotoViews.

On my Soap Box
==============

In my OWN opinion the fact that there will be no backward
compatibility is not an issue.  The fact that the current file
format has been maintained for some 12 years or so is proof that
DataCAD LLC has done their best to maintain compatibility for all
users.  It is simply time to move on to bigger and better things,
and we owe it to ourselves and to the health of a company that we
would all like to see survive, to upgrade to a new file format and a
new program without a lot of bitching.  And cost just shouldn't be a
factor, either. If new versions come out about every 18 months, an
upgrade from v.9 costs 71 cents/day, or $21/month; an upgrade from
v.8.5 costs 90 cents/day, or $27/month; an upgrade from v.8 or
earlier costs $1.27/day, or $38/month.  (How much did we used to
spend each month on drawing leads, erasers, rub-on lettering, ink,
drafting tape, etc.?  Wasn't that the cost of doing business?)

Off my soap box…

Symbol Browser
==============

The new Symbol Browser in DataCAD 11 continues to look more and more
impressive.  Unlike the current template windows the new Symbol
Browser (still with the familiar row/column format) can be undocked
and floated anywhere on your screen, including totally outside of
DataCAD. In fact, since it is now NOT drawing-specific, you can have
multiple drawing files open while one Symbol Browser remains
constantly active on screen (people with dual monitors will REALLY
love this one).

There may be an option in the Symbol Browser to display all the
symbols that are currently in the active drawing file.

Any option that is available for a symbol (Enlarge, DelSymb, etc.)
can be accessed by right-clicking directly on the symbol in the
Symbol Browser.  This includes the ability to display a
Windows-format table with an infinite number of user-definable
fields.  Reports using those fields can be generated without the
current DOS-like method of laying out complicated report tables.

Symbols
=======

There "might" be layers available within symbols in DataCAD 11.

Snapping
========

Snapping is up for a "potential" overhaul.  Essentially you would be
able to snap to anything you can see, including lines of associative
hatching, anything in an XREF, anything in a symbol, etc.

Linetypes
=========

Like hatches, linetype definitions will now be stored within the
drawing file as they are used.  That means that if you send the file
to another DCAD user with a different DCADWIN.LIN file, all the
linetypes will still display properly!  If you open a file that has
a "MYLINE" linetype in it, but you don't have that "MYLINE" linetype
in your .LIN file, it will still display properly as "MYLINE".  If
you want to continue using that linetype in the drawing file you
would just use Identify/SetAll and start drawing.

Intelligent/Parametric Objects
==============================

We did not see much on this subject (it was not officially part of
what Mark was going to talk about), but we did see a little more
than what we saw back in November.  Mark continues to tell us that
the base programming for intelligent objects is solidly in place,
and its just a matter of creating new objects to plug into that
programming.  We saw some smart revision clouds and even some smart
2-line walls.

DWF Export
==========

AutoDesk has a file format called .DWF (also called Whip!), which is
a compressed vector format for the Internet, viewable with a free
plug-in.  It is like a 2D version of o2c in that the files are tiny
and fast.  DataCAD 11 is planning to support the export of drawings
to this format, which actually supports layers and views.  That
means that the anyone viewing the drawing can turn layers on and off
at will, and DataCAD LLC is looking into the possibility of being
able to also export your GotoViews with the .DWF file.

Beta Testing
============
Mark said that once the free 10.05 upgrade is completed and made
available beta testing of DataCAD 11 should start shortly thereafter,
perhaps within the next few weeks.  Beta testing may initially include
two versions: one with single-precision and one with double.

Meeting Notes by:
Michael Smith
William Mitropoulos Associates
DataCAD How-To's:
http://members.bellatlantic.net/~vze2sgzx/dcad.htm