Masks and Blend Effects: Using and Understanding Masks, Gradients, and Blend Effects
MASKS EXPLAINED 94
OPACITY MASKS 96
USING OFFSET PATH TO CREATE A MASK 100
BLEND THEORY 103
BLENDING AND MASKS 105
USING OPACITY MASKS TO CREATE GRADIENTS ON GRADIENTS 109
MASKS WITHIN MASKS 113
CREATE A TRANSPARENT SHADOW 116
As we mentioned in the introduction, many people are baffled by Illustrator’s masking capabilities. There have been numerous attempts over the years to make using masks easier, the latest being the introduction of the “layer clipping mask.” In this section we’ll introduce the two basic types of masks and describe the pros and cons of each.
Clipping Mask or Mask
Masks have been around since the earliest versions of Illustrator, but in version 9, “masks” became “clipping masks.” The functionality is exactly the same; only the name was changed. However, being the artistic nonconformists that we are, when we refer to masks in this book, we are referring to clipping masks.
You can create clipping masks from any type of vector object: paths, compound shapes, or text objects. In short, a mask is a group of objects with the topmost object “masking” all objects below it in the group.
An easy analogy would be to compare a mask to a box of playing cards. The box represents the group, and the cards within the box are the objects. The top card is always the ace (or mask), and the cards beneath it (the objects) can be shuffled in any order.
To create a clipping mask, begin by positioning the object you’d like to function as the mask on top (in the stacking order) of the object(s) you want to mask out. Remember, the easiest way to change an object’s stacking order is by using the Paste in Front/Back command (see “Tip: Arranging Objects Inside Masks”). Then select all objects and press Cmd (Ctrl)-7, or use the contextual menu and choose Make Clipping Mask, or choose Object > Clipping Mask > Make.
Making a clipping mask groups the objects together and, more important, clears the fill and stroke attributes from the top object being used as the mask. Even though releasing the clipping mask (Cmd-Option [Ctrl-Alt]-7) will ungroup the objects, the mask object’s original fill/stroke attributes will not return.
Layer Clipping Masks
A layer clipping mask is almost identical to a regular clipping mask with a couple of notable exceptions. With a layer clipping mask the masking object resides as the topmost object in the layer. As you add artwork to that layer, the objects become masked as long as you position the artwork’s layer underneath the layer clipping mask in the stacking order. The biggest difference, however, is that a layer clipping mask is not automatically grouped.
Since a layer clipping mask depends on using one mask per layer, its usefulness greatly depends on your workflow and the type of work that you do. For involved work that requires a number of masks, using layer clipping masks might prove cumbersome due to the number of layers you’ll need to produce. Also, since the layer clipping masks are not grouped, it might be harder to identify masked objects with a click of the Selection tool as you can with a regular clipping mask.
To create a layer clipping mask go to the Layers palette and click the triangle on the layer to reveal its contents. Make sure that the object you want to be the mask is on top of the stacking order for that layer. Click the layer name (not the object) and either choose Make Clipping Mask from the palette menu or click the Make/Release Clipping Mask button at the bottom of the Layers palette A.