If you use an inkjet plotter, raster plotter, or laser printer that can convert solid areas into screened or gray-shaded areas, you may encounter the problem of shading areas overlapping lines and hiding them. This problem may not be apparent until you actually plot the drawing; it frequently occurs when a gray-shaded area is bounded by lines.
The left side of Figure 13.27shows how shading or solid fills can cover line work. The outline of the walls is obscured by the shading. The right side of Figure 13.27 shows how the drawing was intended to be displayed and printed
Most other graphics programs have specific tools to handle this overlapping difficulty. These tools are commonly named Move to Front or Move to Back, indicating that you move an object in front of or behind another object. AutoCAD offers the Draworder command to perform the same function as the Move to Back and Move to Front tools of other programs.
To force an object to appear above another, choose Tools >- Display Order >- Bring to Front, and then select the object that you want to overlap all the others. Or use Tools >- Display Order >- Send to Back to place an object behind other objects. You can also select specific objects to overlay or .underlay using the Tools >- Display Order >- Bring Above Object and Send Under Object options. For more detailed instructions on how to use Draworder, see Controlling Object Visibility and Overlap with Raster Images.
Drawing Filled Circles
If you need to draw a thick circle, like an inner tube, or a solid filled circle, perform the following steps.
1. Choose Draw> Donut, or type Do.J at the command prompt.
2. At the Specify inside diameter of donut <0-0>: prompt,enter the
desired diameter of the donut “hole.” This value determines the opening at the center of your circle.
3. At the Specify outside diameter .of donut <1.0000>: pro~pt, enter
. the overall diameter of the circle.
4. At the Specify center of donut or <exit>: prompt, click the desired location for the filled circle. You can continue to select points to place multiple donuts.
5. Press .J to exit this process
If you need to fill only a part of a circle, such as a pie slice, you can use the Donut command to draw a full, filled circle. Then use the Trim or Break option on the Modify toolbar to cut out the portion of the donut you don’t need.
Toggling Solid Fills On and Off
Once you have drawn a solid area with the Pline, Solid, Trace, or Donut commands, you can control whether the solid area is actually displayed as filled in. Open the Options dialog box (fools :> Options), then select the Display tab. Locate the Display Performance group in the lower-right comer of the dialog box. The Apply Solid Fill option controls whether or not solid areas are displayed. If the Solid Fill check box ‘does not show a checkmark, thick polylines, solids, traces, and donuts appear as outlines of the solid areas
The Drawing Aids Solid Fill option is an easy-to-remember way to control the display of solid fills. Or you can enter Fill.J at the command prompt; then, at the ON/OFF <ON): prompt, enter your choice of on or off.
There are many valuable uses for polylines beyond those covered encourage you to become familiar with this unique object so you can take full advantage of AutoCAD.
To further explore the use of polylines, try the following exercise, illustrated in Figure 13.30. It will give you an opportunity to try out some of the options discussed in this chapter that weren’t included in exercises.
1. Open a new file called PART13. Set the Snap mode to.25 and be sure that Snap mode is on. Use the Pline command to draw the object shown at step 1 . of Figure 13.30. Draw it in the direction indicated by the arrows and start at the upper-left corner. Use the Close option to add the last line segment.
2. Start the Pedit command, select the polyline, and then type E~ to issue the Edit Vertex option. At the prompt
eXit] <N>: press ~ until the X mark moves to the first corner, shown in Figure 13.30. Enter an S~ for the Straighten option.
3. At the prompt
Enter an option [Next/Previous/Go/eXit] <N>: press ~ twice to move the X to the other corner. Press for Go to straighten the polyline between the two selected comers.
4. Press .J twice to move the X to the upper-right corner, and then enter I ~ forInsert. Pick a point as shown in Figure 13.30. The polyline changes to reflect the new vertex. Enter an X~ to exit the Edit Vertex option, and then press ~ to exit the Pedit command.
5. Start the Fillet command and use the Radius option to set the fillet radius to .30. Press .J to start the Fillet command again, but this time use the Polyline option and pick the polyline you just edited. All the corners fiJ1etto the .30 radius. Add the .15 radius circles as shown in Figure 13.30 ‘and exit the file with the End command.