Methods of combining objects
You can combine vector objects to create shapes in a variety of ways in Illustrator. The resulting paths or shapes differ depending on the method you use to combine the paths.
Pathfinder effects
Pathfinder effects let you combine multiple objects using one of ten interaction modes. Unlike compound shapes, you can’t edit the interactions between objects when you use a Pathfinder effect.
Compound shapes
Compound shapes let you combine multiple objects and specify how you want each object to interact with the other objects. Compound shapes are more versatile than compound paths because they provide four kinds of interactions: add, subtract, intersect, and exclude. In addition, the underlying objects are not changed, so you can select each object within a compound shape to edit it or change its interaction mode.
Compound paths
Compound paths let you use an object to cut a hole in another object. For example, you can create a doughnut shape from two nested circles. Once you create a compound path, the paths act as grouped objects. You can select and manipulate the objects separately using the Direct Selection tool or Group Selection tool; or you can select and edit the combined path.
Pathfinder
Pathfinder panel overview
You use the Pathfinder panel (Window > Pathfinder) to combine objects into new shapes.
The top row of buttons in the panel, make paths or compound paths by default, and compound shapes only when you press the Alt or Option key. You can choose from the following shape modes:
- Add To Shape Area
- Adds the area of the component to the underlying geometry.
- Subtract from Shape Area
- Cuts out the area of the component from the underlying geometry.
- Intersect Shape Areas
- Uses the area of the component to clip the underlying geometry as a mask would.
- Exclude Overlapping Shape Areas
- Uses the area of the component to invert the underlying geometry,
turning filled regions into holes and vice versa.
Shape modes- A.
- All components in Add mode
- B.
- Subtract mode applied to squares
- C.
- Intersect mode applied to squares
- D.
- Exclude mode applied to squares
The bottom row of buttons in the panel, called Pathfinder effects, let you create final shape combinations on the first click. (See Apply Pathfinder effects.)
Pathfinder options
You can set Pathfinder Options from the Pathfinder panel menu or by double-clicking a Pathfinder effect in the Appearance panel.
- Precision
- Affects how precisely the Pathfinder effects calculate an object’s path. The more precise the calculation, the more accurate the drawing and the more time is required to generate the resulting path.
- Remove Redundant Points
- Removes unnecessary points as you click a Pathfinder button.
- Divide And Outline Will Remove Unpainted Artwork
- Deletes any unfilled objects in the selected artwork as you click the Divide or Outline button.
Apply Pathfinder effects
Pathfinder effects let you create new shapes out of overlapping objects. You can apply Pathfinder effects by using the Effects menu or the Pathfinder panel.
Pathfinder effects in the Effects menu can only be applied to groups, layers, and text objects. After you apply the effect, you can still select and edit the original objects. You can also use the Appearance panel to modify or remove the effect.
Pathfinder effects in the Pathfinder panel can be applied to any combination of objects, groups, and layers. The final shape combination is created when you click a pathfinder button; after that, you cannot edit the original objects. If the effect results in multiple objects, they are automatically grouped together.
For a video on using Pathfinder effects and clipping masks and how to import clipping masks into Flash, see www.adobe.com/go/vid0057.
Apply a Pathfinder effect using the Effects menu
- Choose Effect > Pathfinder and choose a Pathfinder
effect.
To quickly apply the same Pathfinder effect
again, choose Effect > Apply [effect].
Summary of Pathfinder effects
- Add
- Traces the outline of all objects as if they were a single, merged object. The resulting shape takes on the paint attributes of the top object.
- Intersect
- Traces the outline of the region overlapped by all the objects.
- Exclude
- Traces all nonoverlapping areas of the objects, and makes overlapping areas transparent. Where an even number of objects overlap, the overlap becomes transparent. Where an odd number of objects overlap, the overlap becomes filled.
- Subtract
- Subtracts the frontmost objects from the backmost object. You can use this command to delete areas of an illustration by adjusting the stacking order.
- Minus Back
- Subtracts the objects in back from the frontmost object. You can use this command to delete areas of an illustration by adjusting the stacking order.
- Divide
- Separates
a piece of artwork into its component filled faces (a face is
an area undivided by a line segment). Note: When you use the Divide button in the Pathfinder panel, you can use the Direct Selection or Group Selection tool to manipulate the resulting faces independently of each other. You can also choose to delete or preserve unfilled objects when applying the Divide command.
- Trim
- Removes the part of a filled object that is hidden. It removes any strokes and does not merge objects of the same color.
- Merge
- Removes the part of a filled object that is hidden. It removes any strokes and merges any adjoining or overlapping objects filled with the same color.
- Crop
- Divides artwork into its component filled faces, and then deletes all the parts of the artwork that fall outside the boundary of the topmost object. It also removes any strokes.
- Outline
- Divides
an object into its component line segments, or edges.
This command is useful for preparing artwork that needs a trap for
overprinting objects. (See Create a trap.)Note: When you use the Outline button in the Pathfinder panel, you can use the Direct Selection or Group Selection tool to manipulate each edge independently. You can also choose to delete or preserve unfilled objects when applying the Outline command.
- Hard Mix
- Combines colors by choosing the highest value of each of the color components. For example, if Color 1 is 20% cyan, 66% magenta, 40% yellow, and 0% black; and Color 2 is 40% cyan, 20% magenta, 30% yellow, and 10% black, the resulting hard color is 40% cyan, 66% magenta, 40% yellow, and 10% black.
- Soft Mix
- Makes the underlying colors visible through the overlapping artwork, and then divides the image into its component faces. You specify the percentage of visibility you want in the overlapping colors.
- Trap
- Compensates for potential gaps between colors in artwork by creating a small area of overlap (called a trap) between two adjoining colors.
Compound shapes
About compound shapes
A compound shape is editable art consisting of two or more objects, each assigned a shape mode. Compound shapes make it easy to create complex shapes because you can precisely manipulate the shape mode, stacking order, shape, location, and appearance of each path included.
Compound shapes act as grouped objects and appear as <Compound Shape> items in the Layers panel. You can use the Layers panel to show, select, and manipulate the contents of a compound shape—for example, to change the stacking order of its components. You can also use the Direct Selection tool or the Group Selection tool to select components of a compound shape.
When you create a compound shape, it takes on the paint and transparency attributes of the topmost component in Add, Intersect, or Exclude mode. Subsequently, you can change the paint, style, or transparency attributes of the compound shape. Illustrator facilitates this process by automatically targeting the whole compound shape when you select any part of it, unless you explicitly target a component in the Layers panel.
- A.
- Original objects
- B.
- Compound shape created
- C.
- Individual shape modes applied to each component
- D.
- Style applied to entire compound shape
Work with compound shapes
Creating a compound shape is a two-part process. First, you establish a compound shape in which all components have the same shape mode. Then, you assign shape modes to the components until you obtain the desired combination of shape areas.
Create a compound shape
- Change the shape mode of any component by selecting it
with the Direct Selection tool or Layers panel and clicking a Shape
Mode button.
Note that you never need to change the mode of the backmost component, because its mode is not relevant to the compound shape.
To sustain maximum performance, create complex
compound shapes by nesting other compound shapes (containing up
to about 10 components each) instead of using many individual components.
Release and expand a compound shape
Releasing a compound shape separates it back into separate objects. Expanding a compound shape maintains the shape of the compound object, but you can no longer select the individual components.
- Select the compound shape using the Selection tool or Layers panel.
- Do one of the following:
Click Expand in the Pathfinder panel.
Choose Expand Compound Shape from the Pathfinder panel menu.
The compound shape is converted to a <Path> or <Compound Path> item in the Layers panel, depending on the shape mode it used.
Choose Release Compound Shape from the Pathfinder panel menu.
Move compound shapes between Illustrator and Photoshop
The shape layers and layer clipping paths (vector masks) in Adobe Photoshop are types of compound shapes. You can import shape layers and layer clipping paths into Illustrator as compound shapes and continue to manipulate them. In addition, you can export compound shapes to Photoshop. Keep the following in mind when using compound shapes with Photoshop:
Only compound shapes that reside at the top level of the layer hierarchy are exported to Photoshop as shape layers.
A compound shape painted with a stroke using a join other than round, or with a weight in points that is not an integer, is rasterized when exported to the PSD file format.
Compound paths
About compound paths
A compound path contains two or more paths that are painted so that holes appear where paths overlap. When you define objects as a compound path, all objects in the compound path take on the paint and style attributes of the backmost object in the stacking order.
Compound paths act as grouped objects and appear as <Compound Path> items in the Layers panel. Use the Direct Selection tool or the Group Selection tool to select part of a compound path. You can manipulate the shape of individual components of a compound path, but you cannot change appearance attributes, graphic styles, or effects for individual components, and you cannot manipulate components individually in the Layers panel.
If you want more flexibility in the compound
path creation, you can create a compound shape and then expand it. Cut a hole in an object using a compound path
- Select the object to use as a hole, and position it so that it overlaps the object to cut. Repeat for any additional objects you want to use as holes.
- Select all the objects you want to include in the compound path.
- Choose Object > Compound Path > Make.
Apply fill rules to compound paths
You can specify whether a compound path is a nonzero winding path or an even‑odd path.
- Nonzero winding fill rule
- Uses mathematical equations to determine if a point is outside or inside a shape. Illustrator uses the nonzero winding rule as the default rule.
- Even-odd fill rule
- Uses mathematical equations to determine if a point is outside or inside a shape. This rule is the more predictable rule because every other region within an even‑odd compound path is a hole, regardless of path direction. Some applications, such as Adobe Photoshop, use the even‑odd rule by default, so compound paths imported from these applications will use the even‑odd rule.
Self-intersecting paths are paths that intersect themselves. You can choose to make these paths either nonzero winding or even‑odd, depending on how you want them to look.
When you create a nonzero winding compound path, you can specify whether overlapping paths appear with holes or are filled by clicking a Reverse Path Direction button in the Attributes panel.
- A.
- Four circular paths
- B.
- Circular paths selected, converted into compound path
- C.
- Reverse Path Direction applied to innermost path
Change the fill rule for a compound path
- Select the compound path using the Selection tool or Layers panel.
- In the Attributes panel, click the Use Non‑Zero Winding
Fill Rule button
or the
Use Even‑Odd Fill Rule button 
.
Change a hole in a compound path to a filled area
- Make sure that the compound path uses the nonzero winding fill rule.
- With the Direct Selection tool, select the part of the compound path to reverse. Do not select the entire compound path.
- In the Attributes panel, click the Reverse Path Direction
Off button
or
the Reverse Path Direction On button 
.
