A clipping path (or "deep etch"[1]) is a closed
vector path, or shape, used to cut out a 2D image in image editing software.
Anything inside the path will be included after the clipping path is applied;
anything outside the path will be omitted from the output. Applying the
clipping path results in a hard (aliased) or soft (anti-aliased) edge,
depending on the image editor's capabilities
By convention, the inside of the path is defined by its
direction. Reversing the direction of a path reverses what is considered inside
or outside. An inclusive path is one where what is visually "inside"
the path corresponds to what will be preserved; an exclusive path, of opposite
direction, contains what is visually "outside" the path. By
convention, a clockwise path that is non-self-intersecting is considered
inclusive.
A compound path results from the combination of multiple
paths (inclusive and exclusive) and the Boolean operations that ultimately determine
what the combined path contains. For instance, an inclusive path which contains
a smaller exclusive path results in a shape with a "hole" (defined by
the exclusive path).
One common use of a clipping path is to cull objects that do
not need to be rendered because they are outside the user's view port or
obscured by display elements (such as a HUD).
