Circle Entities

Circle entities are a combination of multiple line segments that are connected together to form a circle. These entities act as a single line in that they can define the edge of a face and also divide a face. Additionally, selecting one segment of the arc selects the entire Circle entity. However, all inference techniques will operate on the Circle as though it were comprised of segments. For example, every point on the circle is inferred as an endpoint of the segment. Draw circles with the Circle Tool.

Note - You can explode an Circle into regular edge segments using the Explode Curve context menu item (see the Circle Context Menu Items section later in this topic).

Circle entities are comprised of a radius and number of segments. The following image shows a Circle entity with 24 segments.

Note - The model in the previous image contains two entities: a Face entity (in the middle) surrounded by a Circle entity (the circular edge).

Note - Arc and Circle entities are special in that they automatically produce softened edges when extruded using the Push/Pull Tool.

Editing a Circle Entity

You can edit the radius of an Circle entity, that does not yet bound a face, by using the Move Tool. To edit an Circle entity:

1. Select the Move Tool. The cursor will change to an four-way arrow.
2. Move over the Circle entity to locate one of the four cardinal points of the Circle entity.

3. Click and hold on the cardinal point of the Circle entity.
4. Move the cursor to adjust the radius of the Circle entity.

You can also adjust the radius and number of segments using the Circle entity's Entity Info dialog box.

Tip - The inference engine sometimes can get distracted, preventing it from snapping to the center of a circle. You can encourage a center point inference by hovering the mouse cursor over the edges of the circle and then moving it towards the center point.

Editing an Extruded Circle

When you use the Push/Pull Tool to extrude a 2D face that includes a circle, it extrudes a special cylindrical Surface entity which can also have its radius edited. Use the Move Tool to reposition one of the four cardinal edges, and the cylindrical curved face set radius (as well as the radii of the two circle entities that define it) will be adjusted accordingly.

Circle Segmentation

Circles with more line segments appear to have smoother curvature than circles with fewer line segments. However, more line segments increases the size of your model and degrades performance. You can often achieve acceptable results by indicating small segmentation and using smoothing and edge softening to create the impression of smoothness.

Circle Deformation

If an Arc is deformed in a way that destroys its radial definition, such as with a non-uniform scale operation, it will become a non-parametric Curve entity. Polyline Curves can no longer be edited as arcs.