Research on Key Technologies of Component-Based 3D CAD System Development
1 Overview
Since its introduction in 1982, the AutoCAD system developed by Autodesk has been dominated by its ease of use, power and system openness. Become the CAD system of choice in all engineering fields.
In the field of water conservancy and hydropower engineering, the use of AutoCAD platform for secondary development has also achieved a series of results, such as the hydropower station ground plant CAD system, gravity dam CAD system, tunnel CAD system, water machine oil and gas CAD system, geological histogram CAD, which have been developed since the 1990s. Both have achieved good application results. However, the complexity of hydropower engineering design determines that any off-the-shelf CAD software has its limitations. Many problems in the design process can only be solved by the original method. In this paper, through several examples, the application of Lisp language commonly used in the secondary development of AutoCAD in hydropower engineering design is discussed. It is hoped that it can play a role in attracting jade.
VisualLisp language is a new development environment provided by AutoCADR14. It is a product embedded in AutoCAD and combining Lisp language with AutoCAD. It is an intelligent language. AutoLisp allows you to add new AutoCAD commands flexibly and easily, extending AutoCAD's new features almost infinitely.
2 application examples
2 .1 coordinate line
Drawing lines with known coordinate points is a common problem encountered in design work. For example, the processing of data such as river sections, dikes, measured sections, water level flow curves, and kneading curves can be attributed to coordinate line problems. For curves with functional equations such as kneading curves, EXCEL can be used to automatically generate a series of coordinate points according to the desired step size. For measuring the commonly used starting point-elevation data, you can also use EXCEL to convert to coordinate point form.
(1) Using a script file (.SCR)
Use any text editor such as Note, Uedit, Word, Excel, etc. to create a plain text file EX1.SCR, note that the text file suffix must be .SCR, the coordinates are separated by a comma, spaces are not allowed in the file, the last line of the file must Empty return. When the file is created, you can directly add the copy and paste functions in the EXCEL or other files to the script file.
Pline
345.66,238.65
213.45, 124.56
128.44,235.66
After the file is saved, execute “Run Script†under “Tools†in AutoCAD, find and select EX1.SCR in the displayed window, and the drawn line will be displayed immediately on the screen.
(2) Using the LSP program
The coordinate table file EX2.DAT is created, and the suffix is ​​arbitrary. You can input multiple sections of curves in turn, separated by curve names in the middle, and the program automatically draws multiple curves and can label the coordinate table.
"Curve 1"
213.45, 124.56
128.44,235.66
345.66,231.78
"Curve 2"
433.34,567.23
434.12,464.12
Use the "VisulLisp Editor" under the "Tools" menu in AutoCAD to create the DRLINE.LSP file as follows
(defun C:drline()
(if fn
(setq fn (getfiled "coordinate point file name" fn "" 2))
(setq fn (getfiled "coordinate point file name" "" "" 2))
)
(setq f (open fn "r"))
(setq p0 (getpoint "/n line start: "))
(setq bz 0 mm 1)
(command "pline")
(while (/= bz 1)
(setq md (read-line f))
(if (/= md nil)
(setq zbb (read md))
(setq bz 1)
)
(setq dx (car zbb) dy (cadr zbb))
(setq p1 (list (+ dx (car p0))
(+ dy (cadr p0)))
)
(command p1)
(setq mm (1+ mm))
)
(command "")
(close f)
)
After the file is saved, it is loaded and run, which is equivalent to adding the coordinate drawing line command DRLINE. Press the prompt to select the file that stores the coordinate table to realize the automatic drawing curve.
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