Graphics Programs Reference
In-Depth Information
to make drafting production more efficient with AutoCAD, you want to know how to use
blocks, xrefs, PDFs, DWFs, DGNs, and raster files.
A
block
is a collection of objects grouped together to form a single object. You can
insert
this collection more than once in the same drawing, and when you do, all instances of
the block remain identical. By redefining the
block definition,
you can automatically
change all instances of the block insertion (officially called a
block reference
) at once
.
Al-
though a block lives within a specific drawing, you can transfer copies of it into other
drawings. And you can add fill-in-the-blank text fields, called
attributes,
to blocks.
You can create single line or multiline attributes; in addition to having more than one
line, multiline attributes have many of the formatting options of multiline text. And
blocks both with and without attributes can be defined as annotative objects to boot.
(See Chapter 13 for a rundown on annotative objects.)
In this chapter, I present the ABCs of blocks — basic creation and insertion, adding at-
tributes, and getting rid of block definitions you no longer need or want. In Chapter 18, I
show you how to make even more of already-created drawing data, including dynamic
blocks, associative array objects, and several flavors of external reference files (includ-
ing PDFs and MicroStation DGN files) and raster images.
Blocks, along with external references, DWF and PDF underlays, raster images, and DGN
files, enable you to reuse your work and the work of others, giving you the potential to
save tremendous amounts of time — or to cause tremendous problems if you change a
file on which other people's drawings depend. Use these features when you can to save
time, but do so in an organized and careful way so as to avoid problems.
How you use blocks and xrefs depends a lot on the profession and office in
which you work. Some disciplines and companies use these drawing organization
features heavily and in a highly organized way, but others don't. Ask your col-
leagues what the local customs are and follow them.
Rocking with Blocks
First, a little more block theory, and then you can rock right into those blocks. To use a
block in a drawing, you need two things: a block
definition
and one or more block
inser-
tions.
AutoCAD doesn't always make the distinction between these two things very clear,
