Can Chief Arch Draw a Line Tangent to Two Circles
Intro. to Computers for Architecture Majors: § 3: Review of AutoCAD Commands
Instructor: G.Southward. Schmalz
AutoCAD Release 13 has a convenient interface that integrates cartoon display, cartoon and editing tools, and condition information in an piece of cake-to-use multi-window arrangement based on the Microsoft WindowsTM operating system. In this section, nosotros introduce you to the interface, and show how to perform unproblematic AutoCAD commands. This section is organized as follows:
- 3.1. The AutoCAD Interface
3.2. File Commands and Device/Screen Setup
three.three. Graphics Objects and Drawing Commands
Section 3.1 contains an overview of the interface, and Department 3.2 overview the utilize of AutoCAD'south device setup software. Concepts of graphics objects, cartoon commands, and editing procedures are discussed in detail in Section three.3.
3.one. The AutoCAD Interface.
On a Windows-equipped workstation or PC, AutoCAD is invoked by positioning your pointing device cursor (e.chiliad., mouse arrow) over the icon that says "AutoCAD R14", and then double-clicking the left mouse button.
The AutoCAD R14 interface has four salient regions, as shown in Figure three.1 and explained beneath:
Effigy 3.1. Schematic layout of AutoCAD interface.
Drawing Expanse. The large rectangular window in the center of your computer screen is where you enter and view drawings interactively.
Pinnacle Bar. The Top Bar, a narrow strip across the elevation of your screen, contains names of pull-down menus such as File, Edit, View, etc. that control various tools.
Command Window. This three- to five-line rectangular window at the bottom of your computer screen is the expanse where you can enter specific commands by typing on the keyboard. When yous invoke commands from pull-down or clickable menus, the corresponding command text often appears in the Command Window.
Menu Popups. Many of AutoCAD's functions accept been linked to visually explanatory icons that are grouped in several popup windows. The standard Microsoft Windows protocol applies to each window, for convenience. The icons can be activated past positioning your pointing device pointer over the appropriate icon, and then clicking with the left mouse button.
Additionally, the top line of the window displays the file name of an agile drawing.
3.2. File Commands and Device/Screen Setup.
AutoCAD has a user-friendly interface with DOS that readily faciliates file operations such as open, read, and write on AutoCAD drawings. We talk over salient operations on the File bill of fare of the Top Bar portion of the screen, every bit follows.
New: Clears the Drawing Surface area and initializes a new AutoCAD cartoon. Utilise this feature when starting a new project.
Open up: Clears the Cartoon Area and pops up a file selector widget, which prompts you for the name of the drawing you lot want to load. Subsequently you enter the drawing filename, the file is read in and the drawing appears in the Drawing Area.
Save: Stores on the specified disk a cartoon that appears in the Drawing Area. If the drawing is larger than the cartoon surface area, then the entire cartoon is usually saved. An exception occurs when y'all specify a window or viewport (a partition of the drawing) and save that part of the drawing only. Such methods will exist discussed after in the class.
Returning to the file-save procedure, if no disk drive has been specified, and then AutoCAD volition automatically save the drawing to the same disk as the AutoCAD plan runs from (usually C: drive, or some other difficult drive). In order to save your drawing to your floppy disk, you need to specify drive "A:".
Save As: Saves a drawing to disk and allows either a different drive or filename to exist specified. On some of our projects, you will be able to Open up a previous drawing, brand some modifications, and utilise Salve As to salve the modified cartoon under the new project filename.
Exit: This characteristic allows y'all to get out AutoCAD in an orderly mode, and notifies you if there are unsaved drawings (i.e., ones you haven't already saved with the Save or Save Equally commands). If unsaved drawings exist, the file locator popup appears, so you lot can specify a filename and relieve the drawing(south).
Quit: Allows you to do a quick exit, without saving any drawings.
Additional Do: In Section 2, we talked about the interaction of applications programs with the operating organization. Review the notes for that section, and ask yourself what processes might be occurring when AutoCAD opens or saves a drawing. Hint: Ane or two related questions could announced on a quiz.
Another trouble with AutoCAD is setting up the screen when yous are starting afresh with a new version of the software. This situation is not probable to occur when using Academy-supplied computers, but can be difficult for novice users working on habitation computers.
In summary, ane should observe the post-obit conventions when installing a legally registered copy of AutoCAD:
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If you cannot detect the printer driver for your particular type of printer, then call the AutoDesk aid line and ask which i of the drivers supplied with AutoCAD best matches your printer. Beware of occasional anomalous results, equally printer/commuter mismatches tin cause small features of drawings to announced in unpredictable ways.
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Ready your graphics screen using the "CONFIG" command, past entering that control in the Control Window. You will be prompted for various parameters, which you should know earlier yous outset, for case,
- Resolution of your estimator monitor, in pixels
- Type of mouse or pointing device (unremarkably Logitech or Microsoft)
- Color scheme for screen set-upward
A customary color scheme follows:
- Background: White
- Graphics Objects (Cartoon Color): Blackness
- Crosshair Cursor: Red
- Menus: Standard black letters + beige background
Alternatively, a blueish or black background with white drawing color may exist useful, if yous are accustomed to that color combination.
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If you take a plotter attached to your estimator, follow the installation directions, so select the appropriate plotter driver from the list of drivers supplied by AutoDesk. If your plotter is non listed (the vast majority are), then telephone call the AutoDesk help line, as mentioned previously.
Practise not attempt to configure the University workstations, every bit their configuration is set by the systems administrators for general use.
3.3. Graphics Objects and Cartoon Commands.
AutoCAD has several types of graphics objects of interest to this class, including two-dimensional (ii-D) primitives, dimensions, polylines, patterns/fills, and 3-D surfaces and solids. We brainstorm our word of graphics primitives by discussing the drawing commands that make two-dimensional primitives appear on your computer screen.
Line. A line is the basic cartoon tool for all of AutoCAD, and is defined as a line segment between a from-point or origin and a to-point or destination. Lines are drawn with the LINE command, which has the post-obit salient options:
Continuation -- If a LINE command has been terminated, it tin be resumed from the to-betoken of the well-nigh contempo line segment drawn, even though other commands were used since drawing that line.
To activate the CONTINUE selection, ane enters the LINE command in the command window, or clicks on the LINE drawing icon, then enters a carriage return ({Enter} or {Render} key) when prompted for the from-point. A new line will brainstorm at the well-nigh recent to-point.
Closure -- If a LINE control has been used to draw a connected sequence of line segments, so the CLOSURE choice can exist used to describe a line segment that has as its to-point the first from-signal of the line sequence. Geometrically, this has the effect of closing the line effigy to produce a polygon.
To actuate the CLOSURE option, enter "C" when prompted for the to-point. Do non attempt to use the CLOSURE pick if you take interrupted the drawing of a sequence of line segments past executing another command.
Undo -- If a LINE segment has been drawn erroneously and you want to erase it, enter LINE, so UNDO in the control window. The near recent segment drawn will be erased.
More than complicated shapes are bachelor, including circles and arcs, as follows.
Circle. A circle is formed in AutoCAD equally a sequence of straight lines. Enough lines are used so that the viewer is tricked into believing that the smooth contour of a circle is present. This sleight-of-paw works because (a) the calculator's brandish resolution limits the level of particular ane can see when looking at the monitor and (b) the human being visual arrangement tends to smooth jagged curves to make them wait more "natural" to the man brain. Hence, the particular that is nowadays as small straight lines in a many-sided polygon is not visible under nearly atmospheric condition. I'southward visual arrangement therefore infers that such high-resolution polygons are circles.
To depict a circle with AutoCAD, enter the CIRCLE command and choose i of the following options:
Center & Radius (CENRAD) -- With this option, you commencement click where you desire the center point of the circle to be, and then move the pointing device to constitute the perimeter of the circle. The pointing device cursor and the center point circumscribe the circle's radius.
Center & Bore (CENDIA) -- A variation on the CENRAD choice first establishes the eye point of the circle using the pointing device, then allows you lot to specify the circumvolve's diameter by moving the pointing device cursor. Unfortunately, the line segment that visually indicates the diameter begins at the circle's eye, rather than at the perimeter. Hence, the appearance of the circumvolve can be confusing.
iii-Bespeak -- It is a well-known fact of geometry that three points define the perimeter of a circumvolve. Hence, with the three-point choice, ane merely clicks with the pointing device on each of the iii points you want to choose, and a circle appears that passes through all three points.
2-Point -- The two-point circle is a variation on the iii-bespeak selection, and is activated similarly. This characteristic is used for drawing a circle when the diameter is known simply the center is non. Hence, 1 specfies the endpoints of the circle'due south bore, then moves the pointing device to institute the circle'southward perimeter.
Tangent, Tangent, & Radius (TTR) -- Given two lines as shown in Effigy 5.2, the intersection of a circumvolve with each line defines at least two points on the perimeter of the circle. The addition of a radius specification defines sufficient information to draw a circle tangent to both lines. In this option of the CIRCLE control, AutoCAD prompts yous to click on the two lines, then specify the radius of the circumvolve either past entering the radius value in the Command Window, or by moving the pointing device to adapt the circle to meet your requirements.
Effigy five.2. Configuration for tangent-tangent-radius
option of the CIRCLE command.
Arc. An arc is a contiguous partition of the perimeter of a circumvolve. In AutoCAD, arcs are drawn with the ARC command, which has many options. The landmarks of an AutoCAD arc are the showtime and end points, the center of the arc, its length, and the angle subtended, as shown in Figure 5.3.
Hither follow several commonly-used ARC command options:
Figure 5.iii. Landmarks of an arc.3-Point -- Like to the 3-point circle, ane defines an arc by clicking on points along its length.
Center, Start, Terminate (CSE) -- One commencement clicks on the arc's center, and so on each endpoint of the arc. This is useful for drawing nested arcs that have a common center point (e.g., the interior and exterior boundaries of curving sidewalks). There are numerous variations on this option (e.1000., Start, Center, Cease or SCE; CES; etc.)
Center, Get-go, Angle (CSA) -- Occasionally, i needs to specify the angle an arc subtends, together with its center point and start or end point. Similar to the CSE option, in that location are numerous variations (e.g., Start, Angle, Center or SAC; SCA; etc.)
Showtime, End, Radius (SER) -- 1 commencement uses the pointing device to click on each end point of the arc. Then, one tin specify the radius interactively by moving the pointing device and clicking when the desired radius is obtained.
Continuation -- This characteristic is like to the Continuation option on the Line command. That is, i can draw "chained" arcs, where the from-point of the (i+ane)-th arc is the to-point of the i-thursday arc. One does not have to enter the CONTIN pick, just need just press the {Enter} cardinal instead of clicking on the arc's from-betoken. This tin can also be used to draw a line from the terminal endpoint of an arc or concatenation of arcs, where the near recent arc's to-point becomes the line's from-point.
Ellipse. An ellipse can exist thought of as an elongated circle. Ellipses take major and minor axes, every bit well as a eye, as shown in Figure v.4.
The following options pertain to the ELLIPSE command:
Effigy 5.4. Landmarks of an ellipse.Endpoints & Rotation -- One clicks on the two endpoints of a given axis (major or pocket-size), then moves the pointing device to rotate the ellipse to the desired position. If you lot know the rotation angle, you tin can enter in the Command Window instead.
Axis Endpoints + Center -- One tin can besides click on the center of the ellipse, then click on an endpoint of each axis.
We have previously hinted that polygons were important in AutoCAD, when we said that circles are approximated by many-sided polygons. Also, we talked about producing an capricious polygon via the CLOSE option of the LINE command.
Polygon. As shown in Effigy v.five, there are ii primary types of polygon: convex (all exterior angles greater than 180 degrees) and nonconvex. Convex polygons may be regular (all interior angles the same) or irregular (unlike angles).
Effigy five.five. Polygons: (a) convex, (b) regular, and (c) nonconvex.The following process is used with the POLYGON control:
Step ane. You lot will be prompted for the number of sides in the polygon -- enter this number as an integer on the command line, unless you are prompted to enter the number in an alphanumeric text slot in a dialog box. For example, a hexagon has six sides, and the maximum number of sides permitted by AutoCAD is 1,024.
Step 2. Selection the heart of the polygon using the crosshair cursor, guided by your pointing device.
Step 3. You will exist prompted to enter circumscribed or inscribed. A confining polygon has a circle within of the polygon, equally shown in Effigy five.6a. An inscribed polygon is contained inside the circle, equally shown in Figure v.6b.
Figure five.6. Circumscribed and inscribed polygons.Step 4. Enter the radius of the inscribing or circumscribing circle, per the prompt.
The polygon will appear in the Cartoon Window, and yous can rotate it using the pointing device. In some cases, Step 4 tin can be performed with the pointing device, with which one tin can establish the polygon size interactively. Additionally, the "East" pick of the POLYGON command allows you to establish an edge of the polygon, versus the middle (per Step 2). This is useful when aligning a polygon with an existing line.
Some other interesting graphics archaic are tori (plural of torus), which AutoCAD calls "doughnuts".
Definition. A doughnut is a filled circle or ring, as shown in Figure v.7a. The fill material is adamant by the FILL and HATCH commands, which we will review afterward in this course.
Command: DOUGHNUT or DONUT.
Options: Solid circumvolve (per Figure 5.7a), ring with solid fill (Figure 5.7a), figured or design fill up (Figure 5.7b,c), or ring filled with radial lines (Effigy five.7d).
Figure 5.vii. Doughnuts (a) permissible configurations, (b) ring with pattern fill,
(c) filled with solid or pattern, and (d) filled with radial lines.
This concludes our discussion of graphics primitives. We side by side examine the manipulation of AutoCAD graphics and text objects.
Copyright © 1997 by Mark Due south. Schmalz
All rights reserved, except for viewing or printing past UF faculty
or students registered for this class.
Source: https://www.cise.ufl.edu/~mssz/Arch-CGS3470/ACAD-cmd.html
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