Recipe 1.3. Modifying Curves

Problem

You want to modify the curvature of a line segment by curving a straight line segment, modifying the existing curvature, or removing the curve altogether.

Solution

Use the Selection tool (V), following up (if necessary) with the Subselection tool.

Discussion

After a path is created, the Selection tool is often the fastest and most visually intuitive way to modify the curvature of any of its segments. With the Selection tool selected from the Tools panel, hover over any line segment (it should not be selected), and the cursor changes to indicate a curve. Click and drag until the segment is curved as desired, using the path preview as a guide.

Another way to modify an existing curved line segmentand the more precise way, albeit less intuitiveis to use the Subselection tool and the control points. The Subselection tool is more precise because a segment's curvature can be defined independently at each end. If a given line segment is straight, you can add control points by selecting an end point and Alt-dragging (Windows) or Option-dragging (Macintosh).You can add new points to an existing path using the Pen tool. With the Pen tool selected, click on the path where you'd like to add the new point.

To modify a curved segment using control points, use the Subselection tool to select a point adjacent to the segment. When its control points appear, drag them and use the path preview as a guide. Dragging the control points away from the point increases the amount of curvature, and dragging them closer to the point decreases the curvature. Rotating them around the point changes the direction of the curve. When working with end points on a path, there is only one control point. However, points in the middle of a path have two control points. The control point pairs ordinarily move in mirror images to each other. To move one control point independently of the other, hold down the Alt key (Windows) or Option key (Macintosh) while dragging one of the control points.

See Also

Recipe 1.16, Recipe 1.18