Circle by Points Tool Operation

As the Circle by Points tool has several keypresses which can add or change its functionality, we suggest installing the free Astute Graphics plugin Astute Buddy, which creates a panel that dynamically updates to inform you of the various keys which can be pressed in the tool’s current context.

There are several methods of creating circles, depending on the Third Point Must Be Dragged tool preference (see Circle by Points: Preferences).

When the preference is enabled (the default), circles can be created from two points simply by clicking twice (allowing you to scroll, zoom, change the view mode, etc. in the middle of the operation), although they can also be created by clicking-and-dragging. The two points always define the diameter of the circle.

Circle by Points 2 Click Operation

To create a circle from three points, you must not release the mouse button after clicking to create the second point; instead you must start dragging, which positions the third point.

When the preference is disabled, circles can be created from three points by clicking three times. However, to create a circle from two points you must either click-and-drag from the first point, or doubleclick on the second point instead of single click.

Circle by Points Tool 3 Click Operation

By default, the circle’s center, radii, and diameter value will be displayed while creating the circle, but these can be turned on and off independently through the preferences, as can the color of the annotation lines.

While creating a circle using two points, two modifier keys can be used with the Circle by Points tool:

• Shift: Constrains the angle between the first point and the second point to increments of 45° around the constrain angle.

• Option/Alt: Constrains the diameter of the circle to “nice” values, dependent on the current zoom level and units. For example, at 200% zoom, the diameter is constrained to multiples of 2 pt or 0.5 mm.

While creating a circle using three points, as the third point approaches the imaginary line formed by the first two points, the resulting circle approaches infinite size. When its size becomes larger than Illustrator could accommodate, the tool will no longer create artwork but will instead display “Circle too large” by the cursor. In this case, the third point must be moved to a different position.

The Circle by Points tool honors Smart Guides.