Adobe illustrator 10 Manuale Utente

A smooth point always has two direction lines which move together as a single, straight 
unit. When you drag the direction point of either direction line on a smooth point, both 
direction lines move simultaneously, maintaining a continuous curve at that anchor point.

In comparison, a corner point can have two, one, or no direction lines, depending on 
whether it joins two, one, or no curved segments, respectively. Corner point direction lines 
maintain the corner by using different angles. When you drag a direction point on a corner 
point’s direction line, the other direction line, if present, does not move.

Adjusting direction lines on a smooth point (left) and a corner point (right)

Direction lines are always tangent to (perpendicular to the radius of ) the curve at the 
anchor points. The angle of each direction line determines the slope of the curve, and the 
length of each direction line determines the height, or depth, of the curve.

Moving and resizing direction lines changes the slopes of curves.

You create curves by using the pen tool to add anchor points where a curve changes 
direction, and to drag the direction points that shape the curves. To draw individual curve 
segments, see 

Curves are easier to edit and your system can display and print them faster if you draw 
them using as few anchor points as possible. Using too many points can also introduce 
unwanted bumps in a curve. Instead, draw widely spaced anchor points, and practice 
shaping curves by adjusting the length and angles of the direction lines. 

1 Select the pen tool  .

2 Position the pen tip where you want the curve to begin. Hold down the mouse button. 
The first anchor point appears, and the pen tip changes to an arrowhead  .