The Startup Dialog Box

AutoCAD 2002 provides users with two methods to begin drawing with AutoCAD: the Startup dialog and the Today page dialog. Both interfaces provide several methods for starting your drawing session, which allow you to open an existing drawing, start a drawing from scratch, use a predefined drawing template, or use a wizard to walk you through the steps necessary to define your drawing’s configuration.

The Open Drawings tab of the Today page allows you to select an existing drawing. When you click this tab, the interface displays a list of the most recently used drawing files, as shown in Figure 2.1. You may select one of the files in the list, or click the Browse button to locate other files. The Browse button opens the Select File dialog box, which enables you to browse your system’s folders for the drawing file you wish to open.

The other two tabs at the top of the Today page allow you to create new drawings and open a symbol library. Depending on the tab you choose, the Today interface presents you with choices that automate the process of setting up your new drawing’s default setting.

The following sections describe in detail the various ways you can use the Today page to set your drawing’s default values, and provide examples that demonstrate its ease of use.

Starting from Scratch: Understanding AutoCAD’s Default Values

The Start from Scratch option (the second option in the Create Drawings tab of the Today page) is the simplest to use when starting a new drawing. When you choose this option, it presents you with only two choices in the selection area. You can choose English or Metric units of measurement, as shown in Figure 2.2. If you choose English units, AutoCAD creates a new drawing based on the Imperial measurement system, which uses the acad.dwt template file, and sets the drawing boundaries, called LIMITS, to 12×9 inches. If you choose Metric units, AutoCAD creates a new drawing based on the metric measurement system, which uses the acadiso.dwt template file, and sets the drawing limits to 420×297 millimeters.

When you choose English or Metric units, you are actually setting two system variables: MEASUREMENT and MEASUREINIT. The MEASUREMENT system variable sets the drawing units as either English or Metric for the current drawing, whereas the MEASUREINIT system variable sets the drawing units as either English or Metric for new drawings when they are created.

Specifically, the two system variables control which hatch pattern and linetype files an existing or a new drawing uses when it is opened. When the system variables are set to 0, the English units are set, and AutoCAD uses the hatch pattern file and linetype file designated by the ANSIHatch and ANSILinetype Registry settings. When the system variables are set to 1, the Metric units are set and AutoCAD uses the hatch pattern file and linetype file designated by the ISOHatch and ISOLinetype Registry settings.

It is important to determine which system of measurement you will use before starting your drawing because the system of units you select influences how objects appear in your drawing. For example, Figure 2.3 shows two rectangles that contain a hatch pattern. Both hatch patterns are the same (ANSI31), and their rotation and scale are identical: 0 and 1.0000, respectively. However, it is obvious the hatch pattern on the left displays lines much closer together than does the hatch pattern on the right.

The difference in the two hatch patterns occurs because the hatch pattern on the left was drawn first with the MEASUREMENT system variable set to 0 (English units). Next, the MEASUREMENT system variable was set to 1 (Metric units). Then the same hatch pattern was drawn on the right. This example demonstrates that AutoCAD uses two different hatch pattern files based on the current value of MEASUREMENT. Be sure to choose the correct units of measurement to ensure that AutoCAD inserts the proper hatch patterns and linetypes into your drawing.

Using Wizards to Automate Settings

AutoCAD provides wizards to help you set up a new drawing. As you complete setting one value, the wizard takes you to the next, using a standard Windows wizard interface that enables you to go to the next default setting, or back to edit previous settings. By using AutoCAD’s wizards, you can quickly set certain default values and change them again if needed.

Understanding the Wizard Selections

When you choose the Wizard option (the third option in the Creates Drawings tab), the Today page offers two wizard choices: The Advanced Setup and the Quick Setup, as shown in Figure 2.4. The Advanced Setup Wizard takes you through five dialog boxes, allowing you to set values for units, angle, angle measure, angle direction, and area. The Quick Setup Wizard offers a subset of these values, removing options for setting the various values related to angles. Specifically, the Quick Setup Wizard enables you to set values for units and area only.

The following describes the various values you can set with the Advanced Setup Wizard:

• Units. The Units dialog box allows you to set the way linear units are displayed in your drawing.

• Angle. The Angle dialog box allows you to set the way angles are displayed in your drawing.

• Angle Measure. The Angle Measure dialog box allows you to set the base angle from which all angles are measured (it represents 0 degrees).

• Angle Direction. The Angle Direction dialog box allows you to set the direction all angles are measured from the base angle (clockwise or counterclockwise).

• Area. The Area dialog box allows you to set the drawing’s limits, which represent the area in which your model should be drawn and contained.

The Units dialog box allows you to set how AutoCAD displays measured values, such as the length of a line, the radius of a circle, or the area of a polygon. It also controls how AutoCAD displays coordinate values. For example, if the units are set to Decimal, and you list the values of a circle object in a drawing, AutoCAD displays values as shown:

center point, X=   5.8796  Y=   4.2286  Z=   0.0000 
             radius    1.1396 
      circumference    7.1601 
               area    4.0797 

However, if the units are set to Fractional, and you list the values of the same circle, AutoCAD displays values as shown:

center point, X=    5 7/8  Y=    4 1/4  Z=        0 
             radius    1 1/8 
     circumference    7 3/16 
              area    4 1/16 

Notice the difference between the two formats. The Decimal format displays values less than one unit as decimals. In contrast, the Fractional format displays values less than one unit as fractions. This is true even though the values for the exact same objects are listed.

The Units dialog box also allows you to control the precision of the measured values. In Decimal mode, it represents the number of decimal places displayed for a value. In Fractional mode, it represents the smallest fractional increment displayed for a value (for example, 1/32 or 1/64).

When you select a Units value, you are actually setting the LUNITS system variable. The LUNITS system variable is based on integer values, with each integer value representing a units display mode, as shown in Table 2.1.

Additionally, another system variable, LUPREC, controls precision for units. Like the LUNITS system variable, LUPREC uses integer values to determine the number of decimal places displayed with a value. The range of acceptable values is 0 through 8. In the case of values displayed in Fractional mode, the integer value represents a fractional increment. Table 2.2 shows examples of the precision display for each value.

The Angle dialog box allows you to set how AutoCAD displays angle values, such as the angle of an arc, or the angle between two lines. It also enables you to set the precision of displayed angles.

Like the Units dialog box, the Angle dialog box controls two system variables: AUNITS and AUPREC. When you select an angle value, you are setting the AUNITS system variable. The AUNITS system variable is based on integer values, with each integer value representing a units display mode, as shown in Table 2.3.

The AUPREC system variable controls the precision of displayed angles, and functions similarly to the LUPREC system variable, using integer values to determine the number of decimal places displayed with a value. The range of acceptable integer values is 0 through 8. In the case of values displayed in degrees/minutes/seconds or Surveyor’s units, the integer values control the display of minutes and seconds. If the precision value defines the precision beyond minutes and seconds, the seconds are displayed in decimal format. Table 2.4 shows examples of the precision display for each value.

Notice that the Surveyor’s units for integer values 1 and 2, and values 3 and 4, respectively, display the same level of precision. This occurs because minutes and seconds must be displayed as full values. This is true because there are 60 minutes of angular arc in one degree, and 60 seconds of angular arc in one minute.

The Angle Measure dialog box allows you to set the base angle from which all angles are measured. AutoCAD uses the default value of 0 degrees being due East. The Angle Measure dialog box allows you to choose from four preset base angles (East, North, West, or South), and allows you to enter your own user-defined base angle. The value for the base angle is stored in the ANGBASE system variable, and can represent any angle value.

The Angle Direction dialog box works in conjunction with the Angle Measure dialog box and allows you to set the direction all angles are measured from. The only possible directions are counterclockwise or clockwise. The current direction value is held in the ANGDIR system variable, with 0 indicating a counterclockwise direction, and 1 indicating a clockwise direction.

The Area dialog box allows you to set the drawing’s limits, which generally represent the area in which your model is contained or the area within which you will be creating your drawing. The limits are intended to help you manage your drawing.

When you set the width and length of the limits, AutoCAD defines the limits as a rectangle, with its lower-left corner located at coordinates 0,0, and its upper-right corner based on the values you enter for Width and Length. The Width and Length values are stored in the LIMMIN and LIMMAX system variables, respectively.

You can instruct AutoCAD to not allow you to accidentally draw outside the drawing limits, thereby adding a level of error checking to your drawing session. This is called limits checking, and is controlled with the LIMCHECK system variable. By setting the variable to 0, you turn off limits checking, and by setting it to 1, you turn on limits checking. The LIMCHECK variable will only protect you against acquiring points outside the limits. You can copy objects outside limits and position other items as well.

The drawing area within the limits is also the area in which AutoCAD will display its grid. The grid is made up of a series of dots, and is used as a frame of reference when creating objects. The grid is useful for quickly drawing objects based on grid locations. The grid’s visibility is controlled from the Grid button located on the status bar at the bottom of AutoCAD’s screen. You may also press the function key F7 to toggle the grid on and off.

Finally, you can use the limits with the ZOOM command, and when plotting. When zooming, you can select the All option to immediately display the entire Limits area on AutoCAD’s screen. When plotting from model space, you can select the Limits option to plot the entire area defined by the Limits setting.

You have learned how AutoCAD can make starting a drawing easy by using its wizards to walk you through the setup process. Next, you will learn how to take advantage of previous drawing setups by using templates.

Using the Available Templates to Start a Drawing

A template is a drawing file that contains predefined drawing settings and/or geometry, such as a title block, and is used to begin a new drawing. Templates are intended as a quick way to take advantage of an existing drawing that contains the proper drawing settings and base geometry you use in every drawing.

For example, suppose you are creating 10 drawings, and those drawings will use the same units and angle settings, and use the same title block. To minimize your work effort, you can create the drawing once, defining the proper units and angle settings, and inserting the desired title block, then save the drawing as a template. As you begin each new drawing, you select the template file you previously created, which contains the correct units, angle settings, and title block. The template acts as a base for your new drawing, and thereby eliminates a lot of repetitious preparation and setup work.

When you choose the Template option (the first option in the Create Drawings tab of the Today page), AutoCAD displays the list of available templates, as shown in Figure 2.5. AutoCAD 2002 comes with 66 predefined template files, and you can add your own. You create a template file by defining the proper units and angle settings, and inserting any desired geometry, and saving the drawing as a .DWT file.

Customizing and Saving a Template File

Although Autodesk has made a considerable effort to provide a broad array of templates, chances are you will want to customize your own templates. You can do so by modifying one of the template files provided with AutoCAD 2002, or by creating a drawing from scratch.

In the following exercise, you begin with an existing template file, modify a few of its drawing settings, then save the drawing as a new template file.

Exercise 2.1 Creating a Template Drawing

Your newly created template file should appear in the Template list, as shown in Figure 2.8.

The capability to create your own custom templates is very powerful. By creating custom template files, you minimize repetitive tasks and reduce errors by using the same templates repeatedly.

So far, you have seen how to control drawing settings using the Startup dialog box. Next, you will learn how to control drawing settings during the current drawing session.