Arc Spline

Use Arc to create open and closed partial circles made of four vertices.

• Create panel > (Shapes) > Splines > Object Type rollout > Arc
• Standard menu: Create menu > Shapes > Arc
• Enhanced menu: Objects menu > Shapes > Arc

Tip: While creating an Arc spline, you can use the mouse to pan and orbit the viewport between steps. To pan the viewport, drag with the middle mouse button or scroll the mouse wheel. To orbit the viewport, hold down Alt and drag with the middle mouse button or scroll the mouse wheel.

Procedures

To create an arc using the end-end-middle method:

1. Go to the Create panel and turn on (Shapes).
2. Click Arc.
3. On the Creation Method rollout, make sure End-End-Middle is chosen.
4. Drag in a viewport to set the two ends of the arc.
5. Release the mouse button, then move the mouse and click to specify a third point on an arc between the two endpoints.

Creating an arc using the End-End-Middle creation method

To create an arc using the center-end-end method:

1. Go to the Create panel and turn on (Shapes).
2. Click Arc.
3. On the Creation Method rollout, make sure Center-End-End is chosen.
4. Press the mouse button to set the radial center of the arc.
5. Drag and release the mouse button to specify the start point of the arc.
6. Move the mouse and click to specify the other end of the arc.

Creating an arc using the Center-End-End creation method

Interface

Rendering and Interpolation rollouts

Most spline-based shapes share these parameters. For details, see Rendering rollout and Interpolation rollout.

Creation Method rollout

Use this choice to specify the sequence of mouse clicks involved in the creation of the arc.

End-End-Middle

Drag and release to set the two endpoints of the arc, then move and click to specify the third point between the two endpoints.

Center-End-End

Drag and release to specify the radius and one endpoint of the arc, then move and click to specify the other endpoint of the arc.

Keyboard Entry rollout

Creates an Arc spline from the keyboard. Use the X/Y/Z settings to specify the center point and the remaining parameters to specify the radius and arc extents, then click Create. After creating the spline, you can use the Parameters rollout controls to adjust the settings (see following).

Parameters rollout

Once you have created an arc, you can make changes using the following parameters:

Radius

The arc radius.

From

The location of the start point as an angle measured from the local positive X axis.

To

The location of the end point as an angle measured from the local positive X axis.

Pie Slice

When on, adds straight segments from the endpoints to the radial center, creating a closed spline.

Closed pie slice arcs

Reverse

When on, the direction of the arc spline is reversed, and the first vertex is placed at the opposite end of an open arc. As long as the shape remains an original shape (and not an editable spline), you can switch its direction by toggling Reverse. Once the arc is converted to an editable spline, you can use Reverse at the Spline sub-object level to reverse direction.