Masking with vector shapes and images

Vector shapes with Set Clip allow you to set the boundary cut-off of shapes. Masks let you control the transparency of those same shapes in a much more flexible way. Say, for example, we have an illustration of a fish, and we’d like to make it half… I don’t know… squirrel! Sure, why not?

We’d like to gradually fade out the squirrel half into the fish half. That would normally take a lot of complex gradients, but fortunately, we can use a simple black-to-white gradient shape as a mask to fade the squirrel into the fish, as shown in Figure 9.7.

Figure 9.7 – Fading squirrel to fish with a black-to-white gradient set to mask

Note that where the gradient is white, the squirrel head is more opaque and the darker the gradient gets, the more transparency we get. This is the essence of how masks work in Inkscape and many other programs. We can, of course, use radial and even mesh...