LIBRARY ı6ıul 0) - Cranfield University

Appendix A
This appendix shows the geometrical and welding data obtained using the of
line programming module developed for AutoCAD (see Chapter 3). These data are
stored in the CAD drawing as extended entity data associated with the edge curve
that represents the weld joint. The data are presented in Table A. 1 in a list' format, as
they are stored in the AutoCAD database and as they should appear when extracted
from their respective edge using dedicated AutoLISP functions. Parentheses are the
standard form of delimiting each list. It should be noted that a list can contain other
lists. The data shown in Table A. 1 was written in a way that makes it easier to
visualise the different lists contained in it. Each list is defined by a header and the
corresponding value. The header is separated from the value by a point and the list is
delimited by parentheses. The header defines the type of data stored (e. g. integer, real,
vector, string, list delimiter, list type) and the value is the data stored in that particular
position in the major list. For more details, readers are referred to the AutoCAD R12
AutoLISP programming manual.
Before presenting the list, some global and local variables defined in the
programs and some standard AutoLISP functions are defined below:
XDATA: abreviation of extended entity data.
CRANWELD: registered AutoLISP application name. This name must be used in
"WSETUP":
order to retrieve the welding extended entity data.
header for the sublist containing the welding setup.
GASWIRE: global variable containing the list which defines the file of
car;
cad:
caddy.
nth:
"WGEOM":
coefficients for the welding models. The list format is shown
below:
([filename] [default stand-off] [wire diameter] [file description]).
standard AutoLISP function used to extract the first element of a
list. For example, (car GASWIRE) returns the string [filename].
standard AutoLISP function used to extract the second element of
a list. For example, (cadr GAS WIRE) returns real number [default
stand-off].
standard AutoLISP function used to extract the third element of a
list. For example, (caddy GAS WIRE) returns the real number
[wire diameter].
AutoLISP function used to extract the nth component of the list,
the first element being 0 (zero). For example (nth 3 GASIRE)
returns the string [file description], which is the fourth element in
the list.
header for the sublist containing the joint geometry.
1 Data structure used in AutoLISP to store data.
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