AutoCAD 2005 for Dummies

layers, and not a patchwork of the 255 colors that AutoCAD makes available. If you follow my advice, your work to create a color-dependent plot style table will be much reduced, because you’ll have to assign plot properties for only 9 colors, rather than worrying about 255 of them.

  You can use Program FilesAutoCAD 2005SamplePlot Screening and Fill Patterns.dwg for systematic testing of your CTB files. This drawing shows an array of color swatches for all 255 AutoCAD colors. Some of the other tabs (such as Grayscale and Screening 25%) also demonstrate how different CTB files attached to the same layout produce radically different results.

  If you really get carried away and decide to take advantage of the 16 million-odd colors in AutoCAD’s True Color capability, then you’re not going to be controlling lineweights with color-dependent plot styles. CTB plot styles affect the lineweights only of objects that use the traditional 255 colors of the AutoCAD Color Index palette. If you want True Color, use object lineweights or named plot styles to control plotted lineweight.

Plotting through thick and thin

Long ago, manual drafters developed the practice of drawing lines of different thicknesses, or lineweights, in order to distinguish different kinds of objects. Manual drafters did it with different technical ink pen nib diameters or with different hardnesses of pencil lead and varying degrees of pressure on the pencil. Because a computer mouse usually doesn’t come with different diameters of mouse balls or a pressure-sensitive button, AutoCAD and its developers had to figure out how to let users indicate lineweights on- screen and on a plot. They came up with two different ways to indicate lineweight:

? Mapping on-screen colors to plotted lineweights. I describe this common approach in Chapter 4.

? Displaying lineweights on-screen to match what the user can expect to see on the plot. This approach was introduced in AutoCAD 2000.

Controlling plotted lineweights with object lineweights

Plotting object lineweights is trivial, assuming that the person who created the drawing took the trouble to assign lineweights to layers or objects (see Chapter 4 for details). Just make sure that the Plot Object Lineweights setting in the expanded Plot dialog box is turned on. You may also want to turn off the Plot With Plot Styles setting, because plot styles can override the object lineweights with different plotted lineweights.

As long as you turn on the Plot Object Lineweights setting, you’ll find that (those who hate cheap puns, read no further!) the plot thickens! It also thins, but that’s not as funny.

  If you don’t want to plot the lineweights assigned to objects, you must turn off both the Plot Object Lineweights and Plot With Plot Styles settings in the Plot Options area of the Plot dialog box. Turning on Plot With Plot Styles turns on Plot Object Lineweights as well.

Plotting with plodders

Color-as-color and lineweight-as-lineweight seem like great ideas, but Autodesk knew when it added object lineweights back in 1999 that longtime users of AutoCAD weren’t going to abandon the old colors-mapped-to- lineweights approach overnight. Thus, you can still control plotted lineweight by display color in AutoCAD.

AutoCAD veterans by and large have chosen to stick with their Old Way for now. They’ve done so for a variety of reasons, including inertia, plotting procedures and drawings built around the Old Way, third-party applications that don’t fully support the newer methods, and the need to exchange drawings with clients and subcontractors who haven’t upgraded. In summary, the ripple effect of those who need to or want to continue using colors-mapped-tolineweights is lasting a long time. Don’t be surprised if you find yourself going with the flow for awhile.

The default setting in AutoCAD 2005 is to plot object lineweights, so that’s the easiest method if you don’t have to consider the historical practices or predilections of other people with whom you exchange drawings. Mapping screen colors to lineweights requires some initial work on your part, but after you’ve set up the mapping scheme, the additional effort is minimal.

Controlling plotted lineweights with screen colors

To map screen colors to plotted lineweights, you need a color-dependent plot style table (CTB file), as I describe in the section “Plotting with style,” earlier in this chapter. If you’re plotting a drawing created by someone else, that someone else may be able to supply you with the appropriate CTB file, or at least with a PCP or PC2 file from which you can create the CTB file quickly. At the very least, the creator of the drawing should be able to give you a printed chart showing which plotted lineweight to assign to each AutoCAD screen color. Use the instructions in the “Plotting with style” section to copy or create the required CTB file.

  Unfortunately, no industry-wide standards exist for mapping screen colors to plotted lineweights. Different offices do it differently. That’s why it’s so useful to receive a CTB, PCP, or PC2 file with drawings that someone sends you. After you have the appropriate CTB file stored in your Plot Styles folder, follow these steps to use it:

1. Click the tab that you want to plot — the Model tab or the desired paper space layout tab.

2. Click the Plot button on the Standard toolbar.

3. In the Plot Style Table (Pen Assignments) area on the expanded Plot dialog box, select the CTB file from the Name list, as shown in Figure 12-8.

Figure 12-8: Selecting a plot style table that maps screen colors to plotted lineweights.

This action attaches the plot style table (CTB file) to the tab that you clicked in Step 1.

4. Click the Apply to Layout button.

AutoCAD records the plot setting change with the current tab’s configuration information. Assuming that you save the drawing, AutoCAD uses the CTB that you selected as the default plot style when you (or other people) plot that tab in the future.

5. Continue with the plotting procedures described earlier in this chapter.

If your drawing uses a named plot style table instead of a color-dependent plot style table, you follow the same procedure, except that you select an STB file instead of a CTB file in Step 3.

  You can tell whether the current drawing was set up to use color- dependent plot styles or named plot styles by looking at the Properties toolbar. If the last drop-down list (Plot Style Control) is grayed out, the drawing can use color-dependent plot styles. If this list is not grayed out, the drawing can use named plot styles.

Plotting in color

Plotting the colors that you see on-screen requires no special tricks. In the absence of a plot style table (that is, if you set Plot Style Table (Pen Assignments) to None in the Plot dialog box), AutoCAD sends color information as it appears on-screen to the plotter. As long as your output device can plot in color, what you see should be what you get.

If you attach a plot style table to the tab that you’re plotting (as described in the previous section), you can — if you really want to — map screen colors to different plotted colors. In most cases you don’t want that kind of confusion. Instead, leave the Color property in the plot style table set to Use Object Color.

  If your goal is not to plot color, make sure that you set the Color property for all plot styles to Black. If you try to plot colors on a monochrome device, you may find that objects appear in various shades of gray, like in a black and white newspaper photograph, with lighter colors mapped to lighter shades of gray and darker colors to darker shades of gray. This process of mapping colors to shades of gray is called monochrome dithering, and it usually is not what you want in a CAD drawing. To override it, use the Plot Style Table Editor, as described in the section “Creating plot styles,” earlier in this chapter, to set the Color option for all colors to Black (the default setting is Use Object Color). If you don’t already have a plot style table that you want to use, choose Monochrome.ctb (for color-based plot styles) or Monochrome.stb (for named plot styles), both of which come with AutoCAD.