Controlling Object Properties
AutoCAD 2002 provides four object properties you can control through the Layer Properties Manager. The first two—Color and Linetype—are old-timers, having been included in previous versions of AutoCAD. The last two—Lineweight and Plot Style— were new in AutoCAD 2000. The color, linetype, and lineweight properties affect object appearance when displayed on screen, and all four properties control the appearance of objects when plotted on paper.
Through the Layer Properties Manager, you can control the values of object properties. More importantly, the Layer Properties Manager provides a method of globally controlling properties. For example, by using the Layer Properties Manager to change a layer’s color to red, you automatically change the color of all objects on that layer to red. This global method of changing the color of all objects by only changing one value in the Layer Properties Manager is a tremendous timesaver, especially if there are dozens, or even hundreds of objects on a layer. By using the Layer Properties Manager, you can simultaneously edit the Color, Linetype, Lineweight, and Plot Style properties of numerous objects very quickly.
Although this global ability to edit objects is very powerful, it does have one catch: It only works when the properties for each object are set to ByLayer. Fortunately, AutoCAD provides a simple method for setting object properties to ByLayer. By understanding and controlling how AutoCAD assigns properties to objects, you can create objects whose property values are globally controlled through AutoCAD’s Layer Properties Manager.
This section discusses how AutoCAD assigns properties to an object when it is created, and how to use the Layer Properties Manager to control the object’s property values when they are set to ByLayer.
Assigning Properties to New Objects:The Object Properties Toolbar
When you create an object, AutoCAD automatically assigns the object to the current layer. Additionally, AutoCAD also assigns values of Color, Linetype, Lineweight, and Plot Style. These four properties that AutoCAD assigns to an object are determined by the values displayed in the Object Properties toolbar. For example, to assign new objects the layer value of 0, and the color red, you select the desired values from the appropriate drop-down list in the Object Properties toolbar, as shown in Figure 4.3. After these values are set, when a new object is created, it is assigned to layer 0, and assigned the color red. To assign new objects to a different layer, simply choose the desired layer from the layer pull-down list.
Figure 4.3. The Object Properties toolbar sets the Layer, Color, Linetype, Lineweight, and Plot Style properties for new objects.
Note
AutoCAD’s default layer is 0. Geometry created on layer 0 has unique properties with respect to blocks. Consequently, when creating new geometry for your project, you should typically create a new layer for the geometry, reserving layer 0 to create blocks with special properties. For more information on the relationship of layers and blocks, refer to Chapter 13, “Creating and Using Blocks.”
The ByLayer Property Value
Notice that in Figure 4.3 the last three drop-down lists in the Object Properties toolbar all display the current property value as ByLayer. These last three lists are the object property values for Linetype, Lineweight, and Plot Style, respectively. When an object’s property is set to ByLayer, it means those particular property values are controlled by the settings in the Layer Properties Manager. Therefore, with the property assignments shown in Figure 2.6, if you created a new object, its Linetype, Lineweight, and Plot Style values are controlled by the Linetype, Lineweight, and Plot Style values in the Layer Properties Manager. Consequently, to view the values for Linetype, Lineweight, and Plot Style, you must view the values for layer 0 in the Layer Properties Manager, as shown in Figure 4.4.
Figure 4.4. The Layer Properties Manager controls the Color, Linetype, Lineweight, and Plot Style values for all objects whose different property values are set to ByLayer.
Remember that because the Object Properties toolbar is set to layer 0, all new objects are created on layer 0. This means that any properties set to ByLayer when an object is created are controlled by the property values for layer 0. As shown in Figure 4.4, the property values for layer 0 are as follows:
Color = Green
Linetype = Continuous
Lineweight = 0.40 mm
Plot Style = Normal
Note
If the lineweights in your drawing display in millimeters (mm), you can switch to an inches format by choosing Lineweight from the Format menu. Then, from the Lineweight Settings dialog box, select the Inches option in the Units for Listing area. For more information, refer to Chapter 5.
AutoCAD uses these first three property values when drawing an object on screen, and AutoCAD uses all four property values when plotting an object on paper. Once again, AutoCAD looks to the property values in the Layer Properties Manager only when an object’s properties are assigned as ByLayer.
It is important to note that although Figure 4.4 shows the ByLayer color value for layer 0 as green, newly created objects will be drawn in the color red. This is true because the Object Property toolbar shown in Figure 4.3 is set to the color red, and therefore explicitly assigns the color red to newly created objects. So although an object may reside on layer 0, and the ByLayer color value for layer 0 may be white, AutoCAD will display the object’s color as red if the object’s color is set explicitly in the Object Properties toolbar.
Tip
Always assign an object’s property values as ByLayer. This provides you with the ability to globally change Color, Linetype, Lineweight, and Plot Style.
The Color Property
One of the simplest properties to understand is the Color property. AutoCAD provides 256 colors from which to choose, but your color choice should be influenced by two factors:
How objects appear onscreen
How objects appear on paper
For screen appearance, you should typically use various colors to help you differentiate between objects. By using an assortment of colors, you make viewing easier for objects that are drawn close together. However, when it comes to plotting objects on paper, there is more involved to an object’s appearance than just color.
When plotting objects, AutoCAD allows you to assign lineweights by color. For example, when an object that is red is plotted, its lineweight may be 0.002 inches, whereas an object that is green may be plotted with a lineweight of 0.008 inches. The user determines these values at plot time by setting lineweight values in the Plot Style. For more detailed information on controlling lineweights when plotting, see Chapter 20, “Productive Plotting.”
Note
Quite often, the colors you assign to objects are determined by layering standards. If your company or your client has defined color assignments in their layering standards, you should use their color assignments instead of assigning your own.
The Linetype and Lineweight Properties
The Linetype property allows you to set the style of a linetype. A linetype style defines whether AutoCAD draws an object with a continuous, unbroken line, or with dashed or dotted lines. You can choose from a wide variety of non-continuous linetypes, and you can also select linetypes that have text in them. AutoCAD includes an assortment of linetypes, or you can create your own custom linetype styles.
The Lineweight property, on the other hand, controls how heavy a line AutoCAD draws. In fact, the Lineweight property performs the same function as the Plot Style described previously. Instead of assigning lineweights by color, however, it assigns the lineweight as a property. Consequently, you can display the lineweight onscreen, as opposed to observing how wide a line is by plotting the objects. Therefore, you can set one object’s lineweight very thin to make it appear subtle, and set another’s lineweight much wider to make it appear bold, and then view the results on screen and without plotting.
Linetypes and lineweights are described in detail in Chapter 5, “Using Linetypes and Lineweights Effectively.”
In the following exercise, you use the Object Properties toolbar and the Layer Properties Manager to control the color, linetype, and lineweight of objects.
Exercise 4.1 Controlling an Object’s Color, Linetype, and Lineweight
1. |
Open the drawing 04DWG01 from the CD that accompanies this book. The drawing displays a single horizontal red line. |
2. |
From the Object Properties toolbar, choose the Existing Gas Line layer from the drop-down list. (It’s the fifth layer from the top.) Note If the entire layer name is too long to display in the layer drop-down list, hold your cursor over a layer name. After a few moments, AutoCAD displays the entire layer name in a ToolTip, as shown in Figure 4.5. Figure 4.5. When viewing layer names from the Object Properties toolbar’s layer drop-down list, hold the cursor over a shortened layer name to display its full name in the text tip.
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3. |
Draw a circle with its center on the left end of the red line, and with a radius of 1 inch. Notice the circle is drawn with a thin, dashed, green line. |
4. |
From the Object Properties toolbar, from the Color control drop-down list (the second list from the left), choose the color magenta. |
5. |
From the Object Properties toolbar, from the Linetype control drop-down list (the third list from the left), choose the Continuous linetype. |
6. |
From the Object Properties toolbar, from the Lineweight control drop-down list (the fourth list from the left), choose the 0.40mm lineweight. Note Lineweights within AutoCAD 2002 are available in inch and millimeter units. You can choose what units you want to use by using the Format pull-down menu, then Lineweight. The dialog that appears offers a toggle for inches or mm units. |
7. |
Draw a circle with its center on the right end of the red line, and with a radius of 1 inch. Notice that the circle is drawn with a heavy, continuous, magenta line, as shown in Figure 4.6. Figure 4.6. The color, linetype, and lineweight properties can be set to ByLayer or set explicitly.
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8. |
Notice how dramatically different the two circles are in Figure 4.6. Although both circles are drawn on the same layer, the circle on the right is assigned its color, linetype, and lineweight explicitly by the values in the Object Properties toolbar. The circle on the left, on the other hand, has its color, linetype, and lineweight values set to ByLayer. Therefore, AutoCAD draws the circle on the left based on the values of color, linetype, and lineweight set for the Existing Gas Line layer in the Layer Properties Manager, as shown in Figure 4.7. Figure 4.7. The color, linetype, and lineweight values are highlighted for the Existing Gas Line layer in the Layer Properties Manager.
Next, you use the Layer Properties Manager to modify the color, linetype, and lineweight values. |
9. |
From the Objects Properties toolbar, click the Layers button (the second button from the left). The Layer Properties Manager dialog box appears. |
10. |
From the Existing Gas Line layer, under the Color column, choose the box marked Green. The Select Color dialog box appears as shown in Figure 4.8. Figure 4.8. The Select Color dialog box allows you to choose any one of 256 colors.
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11. |
From the Select Color dialog box, choose the Blue color, then click OK. AutoCAD sets the Existing Gas Line layer color to blue. |
12. |
From the Existing Gas Line layer, under the Linetype column, choose the DASHED linetype. The Select Linetype dialog box appears as shown in Figure 4.9. Figure 4.9. The Select Linetype dialog box allows you to choose a layer’s linetype.
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13. |
From the Select Linetype dialog box, choose the CENTER linetype, then click OK. AutoCAD sets the Existing Gas Line layer linetype to CENTER. |
14. |
From the Existing Gas Line layer, under the Lineweight column, choose the 0.35 mm lineweight. The Lineweight dialog box appears as shown in Figure 4.10. Figure 4.10. The Lineweight dialog box allows you to choose a layer’s lineweight.
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15. |
From the Lineweight dialog box, choose the 0.35 mm lineweight, then click OK. AutoCAD sets the Existing Gas Line layer lineweight to 0.35 mm, as shown in Figure 4.11. Figure 4.11. The Existing Gas Line layer’s new color, linetype, and lineweight are modified in the Layer Properties Manager.
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16. |
From the Layer Properties Manager, click OK. AutoCAD updates the circle on the left to reflect the property changes made in the Layer Properties Manager, as shown in Figure 4.12. Figure 4.12. The circle on the left displays the new property values set in the Layer Properties Manager.
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17. |
Notice that the appearance of the circle on the right did not change. This is true because the circle on the right had its properties set explicitly from the values you set in the Object Properties toolbar. Next, you complete this exercise by reassigning the properties of the circle on the right to ByLayer. |
18. |
Choose the magenta circle on the right. AutoCAD highlights the object, indicating that it is selected. |
19. |
From the Object Properties toolbar, from the Color control drop-down list, choose ByLayer. |
20. |
From the Object Properties toolbar, from the Linetype control drop-down list, choose ByLayer. |
21. |
From the Object Properties toolbar, from the Lineweight control drop-down list, choose ByLayer. AutoCAD redraws the circle on the right, as shown in Figure 4.13. Figure 4.13. Choosing ByLayer from the Color, Linetype, and Lineweight control drop-down list resets the selected circle’s properties.
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Notice that although the circle on the right remains selected, the Color, Linetype, and Lineweight controls display ByLayer as the current type. However, if you deselect the circle by pressing the Esc key once, the values you originally set for color, linetype, and lineweight are redisplayed. This occurs because AutoCAD shows the currently selected object’s property values in the Object Properties toolbar. This includes the selected object’s layer and Plot Style assignments.
Tip
A small enhancement made in AutoCAD 2000i was the ability to clear selected objects and grips with a single Esc key press as opposed to two. Although most of us end up pounding the Esc key five or more times, now you only have to press it once!
You can close the drawing without saving your changes. However, before exiting AutoCAD, be sure to deselect all objects, and then change the color, linetype, and lineweight values back to ByLayer in the Object Properties toolbar.
The Plot Style Property
AutoCAD 2000 provided a new object property called Plot Style. This property affects how objects appear when plotted by allowing you to assign a Plot Style to an object and override its color, linetype, and lineweight values. Additionally, Plot Styles allow you to specify end, join, and fill styles, as well as control output effects such as dithering, grayscale, pen assignment, and screening.
Plot Styles are intended to allow you to plot the same drawing in many different ways without making elaborate changes to the original Color, Linetype, and Lineweight properties. By creating multiple Plot Style tables, you can create one plot of a drawing that displays objects with bold, heavy lines, and then plot the same drawing as a grayscale, all without making any changes to object Color, Linetype, or Lineweight properties.
Note
For more detailed information on Plot Styles, see Chapter 20, “Productive Plotting.”