When working in Illustrator we tend to think of our vector shapes in terms of the points, or nodes, that make up each shape. However, each shape is a combination of the both the points and the segments that join them. Because our control system (the Beziér Handles) stem from the points it’s easy to forget that we can in fact select and edit via the segments.
In the image below we can see the top-most point in the circle is active. We can alter the position of the point and the curves will adjust accordingly, or we can alter the curves themselves using the Beziér Handles.
In the second image things are a little different. Notice that all the points have a white centre indicating that they are not active but we can see two Beziér handles. In this case it is the segment rather than the points that is active.
We can use the Direct Selection tool here to manual adjust the shape – simply click and drag to pull the segment into a new position. If you hold down the Shift key your movement will be constrained to 45 degrees.
One function I find particularly useful is the ability to use the arrow, or cursor keys to edit the active segment. This gives more precise control over movement in each axis – remember you can use the Shift Key when using the cursor keys for moving in larger increments.
As we can see in the image below I’ve increased the curve value equally in both axis, something that’s much harder to do with manual adjustment.
So, whilst the points are central to controlling and editing in Illustrator don’t forget that segments can also play a role when editing vectors.