The top row of the Pathfinder panel contains four functions, called shape modes, which are used to combine multiple selected shapes in different ways. Once a shape mode is applied, the resulting shape is referred to as a compound shape.

When you create a compound shape from multiple selected objects, the resulting shape appears as a single object and takes on the attributes of the topmost object. Using the Direct Selection tool, you can select the individual objects in the compound shape and edit them. See the sidebar “Illustrator Shape Modes and Photoshop Shape Layers” for additional functionality that you can take advantage of when using compound shapes.

The following are the four shape modes you can choose from in the Pathfinder panel:

• Add. The Add shape mode combines all the selected shapes and gives the appearance as if they were all joined together. This function replaces the Unite pathfinder, which you can find in older versions of Illustrator.
• Subtract. The Subtract shape mode combines all the selected shapes and takes the top objects and removes them from the bottommost object. This function replaces the Minus Front pathfinder, which was found in older versions of Illustrator.
• Intersect. The Intersect shape mode combines all the selected shapes and displays only the areas in which all the objects overlap with each other.
• Exclude. The Exclude shape mode combines all the selected shapes and removes the areas in which the objects overlap with each other.

It is certainly useful to be able to select the individual objects of a compound shape, but many times you just want to create a new shape that combines all the selected shapes. To do so, you can expand a compound shape by clicking the Expand button in the Pathfinder panel. If, when you’re creating a compound shape, you know that you want to expand it, you can hold the Option (Alt) key while clicking the Add, Subtract, Intersect, or Exclude button. This applies the function and expands the shape in one step.

Additionally, you can release a compound shape by choosing Release Compound Shape from the Pathfinder panel menu. Releasing compound shapes returns the objects to their individual states and appearances.

If you think about it, Live Paint allows you to apply attributes—such as fills and strokes—to paths based on their appearance as opposed to their actual makeup. It would be even nicer if you could actually edit your paths based on appearance as well, don’t you think? Adobe was apparently reading your mind (a scary thought) and added another tool to the mix—the Live Paint Selection tool—that enables you to select portions of objects based on their appearance.

Let’s take a look at an example. Use the Line Segment tool to draw two perpendicular lines, creating an X. Select both paths, and press Command-Option-X (Control-Alt-X) or choose Object > Live Paint > Make to convert the two paths into a Live Paint group. Now, select the Live Paint Selection tool, and click one of paths. You’ll notice that you can select each segment of the line individually. What were two paths before are now four line segments. With one segment selected, press the Delete key to remove that segment from the path. Select another segment, and change its Stroke attribute. You can also click one segment and then drag to select other segments in one step.

The Live Paint Selection tool can also select the fills of Live Paint areas. If you have two overlapping shapes in a Live Paint group, you can select the overlap and delete it. You can also double-click to select continuous areas of similar attributes and triple-click to select similar attributes across the entire Live Paint group.

At the end of the day, Live Paint adds a more flexible way to color and edit paths, and it also adds more value to the Pencil tool, because complete closed paths aren’t required. The important point to remember is that a Live Paint group is a group, and anything you can do with a group in Illustrator you can do with Live Paint groups as well. For example, you can add attributes such as strokes to the Live Paint group for interesting effects. Experimenting with the Live Paint feature certainly helps you when you’re editing paths, and the good news is that it’s a fun feature to use.

Live Paint groups can be expanded, at which time they behave like ordinary vector paths. The appearance of an expanded Live Paint group remains identical to the original, but it is split into multiple objects for both fills and strokes. This is similar in concept to expanding live effects. To expand a selected Live Paint group, either click the Expand button in the Control panel or choose Object > Live Paint > Expand.

From a production standpoint, you don’t need to expand Live Paint groups in order to prepare a file for print. Live Paint groups print perfectly, because Illustrator performs the necessary expanding of paths at print time (similar to live effects).

Additionally, you can choose Object > Live Paint > Release to return a Live Paint group to the original paths used to create it. Where expanding a Live Paint group results in objects being broken up in order to preserve appearance, releasing such a group preserves the geometry of the original paths, but the appearance or colors are lost.

Let’s take a moment to understand how Live Paint works. When you select several overlapping paths or shapes and click them with the Live Paint Bucket tool, you are creating a Live Paint group. This is a special kind of group in which object stacking order is thrown out the window. All objects in a Live Paint group are seemingly combined onto a single flat world, and any enclosed area acts as a closed shape, which can be filled with color.

Although clicking several selected paths is the easiest way to create a Live Paint group, you can also select several paths and choose Object > Live Paint > Make to create a Live Paint group. Once you’ve created a Live Paint group, however, you may find that you want to add paths or shapes to the group. To do so, draw the new paths, and use the Selection tool to select the existing Live Paint group and the new paths. Then choose Object > Live Paint > Add Paths. The new paths will become part of the group, and any intersecting areas will act as individual areas that you can fill with color.

Live Paint groups can also utilize the Group Isolation Mode feature that enables you to draw objects directly into existing groups. Using the Selection tool, double-click an existing Live Paint group to enter Group Isolation Mode. Now switch to any shape or path tool to add paths directly to the Live Paint group. This ability to add paths directly to a Live Paint group is extremely powerful because it allows you to define regions for color in just a few quick steps. Using Pathfinder filters to create multiple overlapping shapes is no longer required for such tasks.

In the Toolbox, double-click the Live Paint Bucket tool to change its behavior. By default, the Live Paint Bucket tool affects only the fill of a path, but you can also set the tool to apply color to strokes as well. Additionally, you can specify the color that the Live Paint tool uses to highlight closed regions.

Let’s take a moment to understand how Live Paint works. When you select several overlapping paths or shapes and click them with the Live Paint Bucket tool, you are creating a Live Paint group. This is a special kind of group in which object stacking order is thrown out the window. All objects in a Live Paint group are seemingly combined onto a single flat world, and any enclosed area acts as a closed shape, which can be filled with color.

If you move a path so that an enclosed painted area becomes unpainted, Illustrator doesn’t remember that the region was filled with a color prior to the edit. Moving the path back to its original position will not bring back the fill; you’ll need to reapply the fill color.

Although clicking several selected paths is the easiest way to create a Live Paint group, you can also select several paths and choose Object > Live Paint > Make to create a Live Paint group. Once you’ve created a Live Paint group, however, you may find that you want to add paths or shapes to the group. To do so, draw the new paths, and use the Selection tool to select the existing Live Paint group and the new paths. Then choose Object > Live Paint > Add Paths. The new paths will become part of the group, and any intersecting areas will act as individual areas that you can fill with color.

Live Paint groups can also utilize the Group Isolation Mode feature that enables you to draw objects directly into existing groups. Using the Selection tool, double-click an existing Live Paint group to enter Group Isolation Mode. Now switch to any shape or path tool to add paths directly to the Live Paint group (Figure 4.54). This ability to add paths directly to a Live Paint group is extremely powerful because it allows you to define regions for color in just a few quick steps. Using Pathfinder filters to create multiple overlapping shapes is no longer required for such tasks.

Figure 4.54 In Group Isolation Mode, you can draw new paths in an existing Live Paint group to instantly create additional regions that can be filled with color.

You can use the Live Paint Bucket tool to color multiple regions with a single color in one step by clicking one region and dragging the pointer across additional contiguous regions.

In the Toolbox, double-click the Live Paint Bucket tool to change its behavior. By default, the Live Paint Bucket tool affects only the fill of a path, but you can also set the tool to apply color to strokes as well (Figure 4.55). Additionally, you can specify the color that the Live Paint tool uses to highlight closed regions.

Figure 4.55 You can set the Live Paint Bucket tool to apply color to strokes in a Live Paint group as well.

Unfortunately, the Live Paint feature doesn’t work with paths that have brush attributes applied. If you do try to turn paths with brushes into a Live Paint group, the appearance of the brush will disappear, leaving just the appearance of the stroke.

When using the Live Paint Bucket tool, you can press the Shift key to toggle between painting the fill and painting the stroke.

First you’ll create something using Live Paint to get a feel for what the feature is all about. Then we’ll discuss how the feature works, and at that point, you’ll better understand how to use it in a meaningful way. Select the Line Segment tool, and draw two parallel vertical lines and two parallel horizontal lines to create a tic-tac-toe board. Don’t worry if the lines or spacing aren’t perfect—for this exercise, you just want to make sure the lines cross each other.

Select the four lines, and select the Live Paint Bucket tool. As you move your pointer over the four paths, the paths become highlighted. Click once to create a Live Paint group. Now, choose a fill color (a solid color, gradient, or pattern) from the Control panel, and move your pointer over the center area of the tic-tac-toe board. The enclosed area in the middle becomes highlighted in red, which indicates an area that you can fill with color. Click once with the Live Paint Bucket tool to fill the highlighted area.

The resulting behavior is very Photoshopesque—you’ve filled an area that is enclosed on all sides, but you didn’t fill an actual object. Choose the Direct Selection tool, select one of the paths, and move it just a bit. Notice that the color in the area updates to fill the center. If you move one of the paths far enough to the side so that it no longer touches the other paths, you’ll find that the fill color disappears, because there is no longer an enclosed area to fill.

While working on revision after revision of a file, your document may become littered with stray anchor points, empty text objects, or unpainted objects (those that have neither a fill nor a stroke applied). Having these objects present in a file can be problematic for a variety of reasons. Empty text objects may contain references to fonts, and you, thinking that those fonts aren’t there, may forget to include them when you send source files to prepress. Additionally, stray points in a file can cause files to export with unexpected size boundaries and could lead to corrupt files.

Choose Object > Path > Clean Up, and choose which of these elements you want to automatically remove from a file. Beware that to Illustrator, a stray point is a single anchor point with no path. Some designers use Scatter brush art by using the paintbrush to click just once to place a single instance of a brush. Running the Clean Up command to delete stray points deletes these Scatter brush objects from a file as well. In reality, it’s better to use Symbols rather than Scatter brushes for these designer tasks, something we’ll discuss in Chapter 5, Brushes, Symbols, and Masks.

You may find that some vector paths contain unnecessary anchor points. By unnecessary, we mean you might be able to create the same path with fewer anchor points. Too many unnecessary anchor points on a path translates into more complex files that take longer to print and that are more difficult to edit.

You’ll often come across this problem when you’re importing files from CAD applications or when you’re using vector tracing programs such as Adobe Streamline (the Live Trace feature in Illustrator, covered in Chapter 9, Mixing It Up: Working with Vectors and Pixels, does not suffer nearly as much from this problem).

To reduce the number of anchor points on a path, select the path, and choose Object > Path > Simplify. You can use the Preview option to see the results as you change the settings. The Simplify dialog also gives you real-time feedback on the number of anchor points on the original path and the number of points using the current Simplify settings. The dialog also offers the following settings:

• Curve Precision. This controls how closely the simplified path matches the curves of the original selected path. A higher Curve Precision setting results in a path that more closely matches the original but that has fewer reduced anchor points.
• Angle Threshold. The Angle Threshold setting determines the smoothness of corners. If the angle of a corner point is less than the Angle Threshold setting, the corner point is not changed to a smooth anchor point.
• Straight Lines. This setting forces the simplified path to only use corner anchor points, resulting in a path that is far less complex. Of course, the path may not match the original that well, but this option may be useful in a creative mind-set.
• Show Original. With the Show Original option checked, Illustrator displays both the original path and the simplified result, allowing you to preview the difference between the two.

A compound path is a single path that consists of more than one path. That sounds like an oxymoron, no? Think of the letter O in the alphabet. It appears to be a large circle with a smaller circle cut out from its center. How is such a shape created with Illustrator? The answer is by drawing two circles and combining them to become a single compound path. You do this by choosing Object > Compound Path > Create. The result is a shape with a hole cut out of the middle. Compound paths are treated as one entity, and therefore, both paths that make up this compound path take on the attributes of the bottommost path. If your compound path consists of multiple shapes, Illustrator does its best to figure out which paths become hollow and which appear solid.

Illustrator uses one of two methods to decide which paths of a compound shape are hollow and which are solid. The default method is the Non-Zero Winding Fill Rule method; Illustrator can also use another method, the Even-Odd Fill Rule method. You’ll find both of these buttons in the Attributes panel, and you can choose them when a compound path is selected on the artboard. By default, Illustrator uses Non-Zero Winding Fill Rule and makes the bottommost path clockwise and all the other selected paths counterclockwise.

When you create a compound path and click Non-Zero Winding Fill Rule, you can manually reverse the path direction to control whether a shape is hollow or solid. Use the Direct Selection tool to select the path you need, and click the appropriate button in the Attributes panel.

When editing paths, you might find you need to cut or split a path at a certain point. With the Scissors tool selected, you can click any topmost vector path (selected or not) to cut the path. In essence, you create two anchor points by doing this. The Scissors tool can cut only one path at a time.

The Knife tool is much like the Scissors tool, only you cut or split a path by dragging the pointer across a path instead of clicking it. Whereas using the Scissors tool results in an open path, using the Knife tool results in at least two closed paths. The Knife tool cuts through multiple paths when nothing is selected, but cuts through only objects that are selected (even if those selected objects appear beneath other objects).

Using the Scissors or Knife tool is unwieldy at best, and you may find that if you’re doing a lot of path editing, you’ll get better results using Live Paint groups.

Using the Eraser Tool

Adobe Illustrator CS3 features a new tool called the Eraser tool. Unlike the Path Eraser tool, the Eraser tool works as you would expect—it simply erases parts of objects. That being said, the Eraser tool has a variety of settings, and you should know about some “side effects” as well.

You’ll find the Eraser tool in the lower part of the Tools panel, grouped with the Scissors and Knife tools. To use the Eraser tool, select it, and then click and drag over any object (or objects). If nothing is selected, the Eraser tool will erase all objects across all layers in your document, with the exception of locked layers, of course. For more control, you can make a selection first and then use the Eraser tool, at which time the tool will erase only those objects that are selected (leaving all other objects intact).

It’s important to realize that although the Eraser tool is cool and makes it seem effortless to quickly remove parts of an illustration, the tool still must abide by the general rules of how vector objects are drawn. This means if you try to erase part of a single closed path, the result will be two closed paths, not open ones. It’s easiest to see this when attempting to erase paths that contain strokes. In addition, although you can certainly use the Eraser tool to erase portions of a stroke, you must reapply the strokes to each segment of the resulting path. In the latter case, you can get around this by first applying the Object > Path > Outline Stroke command before using the Eraser tool. The same applies when trying to erase paths with brushes applied (refer to Chapter 5, Brushes, Symbols, and Masks, for more information on brushes).

Once you get used to the behavior of the Eraser tool, it becomes a useful (and fun!) tool to use. Even better, you can adjust some really powerful settings to get the full potential of the Eraser tool. First, you can adjust the size of the eraser by tapping the bracket keys on your keyboard (just as you would adjust brush size in Photoshop). You can also double-click the Eraser tool in the Tools panel to open the Eraser Tool Options dialog. You can manually adjust the numerical values for the angle and roundness of the Eraser tool, or you can click and drag the black dots and the arrow in the preview near the top of the dialog to adjust those values visually. You can adjust the size of the diameter of the eraser as well.

By default, all the values are fixed, meaning they remain consistent as you use the Eraser tool. However, you can choose to make the values random and select a variation for each setting. Even better, if you have a pressure-sensitive tablet (such as the one from Wacom, for example), you can choose other variables including Pressure. For example, setting Diameter to Pressure with a high Variation value gives you the ability to erase with more control and flexibility.