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On programming access to dynamic blocks from AutoLISP
On December 8, 2016 the author of Mysteries of Autodesk's Caves passed away. See article on Andrey Lazebny at isicad.ru.
Link
to J.Bergmark's blog with this theme
Dynamic blocks appeared for the first time
in AutoCAD version 2006, that declared beginning of parametrization in this
popular graphical product. Unlike static blocks existing before the dynamic
blocks have possibilities for including parameters
(coordinates, lengths, angles, etc.) to be impacted by
actions (move, stretch, rotate, etc.). As a
result of impact the block's appearance can suffer significant changes.
Visibility parameters provide opportunity of
combinig several views in a block (e.g. three projections of a product). One
tool more - lookup tables - enable saving all
the possible dimensions of an object (e.g. all the dimensions of one beam).
That's why dynamic blocks attracted attention of AutoCAD users who did not
constrain themselves by basic drafting instruments. Those users wish to build
such objects to be easily transformed. Readers can find sample dynamic blocks in
the
Tool Palettes modeless window with panels for architectural, civil, and
other blocks (symbols). See the book
"AutoCAD 2006/2007. New Facilities". Pay
attention that raster previews of dynamic blocks have a yellow icon on them: 
.
Of course this remarkable tool was noticed by programmers and CAD managers.
But internal organization of dynamic blocks is so complicated and its
description is so poor that it became a barrier for many researchers. For many
but not for all.
Andrey Lazebny is a Moscow programmer and is
one of the diggers of AutoCAD depths who tried working with AutoLISP language to
catch the sense. He published his conclusions on the
dwg.ru forum and then
designed as a story being shown here. The story is titled
Mysteries of Autodesk's Caves and is written in a lively joke manner.
It is divided into 11 parts:
Example of a simple dynamic block created in version 2007 and used in the story
can be
downloaded here.
You can find texts of AutoLISP programs here:
And you can see there a dynamic block having multiple visibility parameters. The block was created with the programs mentioned.
I invite all the comers to take a closer look at this material and to try
extending it. Besides information on dynamic blocks the reader will see methods
of communication with the AutoCAD object model using ActiveX technology.
You may write to the author by email ( lazebny#pelisker.ru ), changing # to a necessary symbol
and putting AutoLISP & AutoCAD in the message topic.
N.Poleshchuk (introduction and translation)