Pattern fills in Adobe Illustrator are simple to do. It requires an understanding of what defines a pattern shape, and how to position artwork within it.
Parts of the Pattern
A pattern swatch is created and placed in the Swatches palette. Illustrator has two patterns in the default document’s palette: a blue background with white wavy lines, and an orange background with white dots. Draw an area on the document and choose one of these pattern fills and the result is a repeated pattern of the swatch.
But what makes up a pattern swatch? Simply drag a pattern swatch to an open document area and the composition of the swatch can be seen. The wavy blue pattern is made of a blue square and white strokes. But there’s another important item which can’t be seen.
Invisible Bounding Box is Crucial
Underneath all the artwork of a pattern swatch is a square (or rectangle) with the stroke and fill set to “none”. This invisible item or “bounding box” defines the area of a pattern. The blue wave pattern has a bounding box identical in size to the blue background and cannot be “seen” even in outline mode without hiding the blue square. In the example shown below, the bounding box has been indicated by a dotted line. Note the wavy lines run over the edges of the bounding box.
The bounding box must be the bottom-most item in a pattern swatch. When creating a pattern, make sure there is a square or rectangle with no stroke or fill placed at the bottom. It must not be on another layer.
Pay Attention to the Edges
In the example below, the waves roll off one side and appear on the other side with the same motion. This is critical to maintaining a consistent pattern. If a graphic goes out of the bounding box on one edge, it must continue into the box from the opposite side. The wave swings down through the right side, it must reappear at the same location on the left side, continuing the curve of the wave.
Think of it this way: remember the video game Asteroids? The asteroids float across the screen and when they disappeared off the sides, they reappeared on the opposite sides, moving at the same angle. Illustrator patterns need to be set up in this manner.
Creating and/or Editing Patterns
A pattern swatch can be added to the swatch palette by selecting the entire group and dragging it to the palette. It’s that simple. Make sure the bounding box was included. If it isn’t, the result will the entire group of graphics, including the art placed outside the intended bounding area. This will result in an inconsistent pattern with gaps.
An existing pattern can be edited like any Illustrator artwork. To replace an existing swatch with an edited version. hold down the option (Mac) or alt (Win) key while dragging the swatch to the palette and drop it on the old swatch. If any artwork contained the old pattern, it will be replaced with the new pattern. If a new variation of a pattern is desired, drag it to the palette after editing without the modifier keys mentioned above.
Moving Objects with Patterns
Patterns are placed on a document in relation to the upper left corner of the document. Move a filled area around and notice that the pattern does not move. Shapes stay in the same location on the page. To move a pattern within a space, hold down the tilde key (~, next to the 1 on the keyboard) and the pattern will move, but not the object containing it.
Benefit of Using Patterns
For a complex background, using a pattern swatch can result in smaller file sizes. This is because an object uses a representation of a small swatch and repeats it. View a filled object in Outline mode will show there are no objects in the fill area. If a user wants to modify a large pattern area, they can choose to Object > Expand to turn the whole area into editable shapes. This will result in many objects on the page and increase file size.
Using patterns allows a user to create a complex background without having to repeat positioning of many carefully crafted object across a page. Any object can be used in a pattern, even photos. But patterns cannot be used within other patterns.
 |
