To Create a Planar Curve
A planar curve lies on a specified plane. You cannot move the curve points outside the specified plane while editing, unless you convert the curve to a free curve.
1. Click 
Style > 
Curve. The Curve tab opens.
Style > Curve. The Curve tab opens.2. To create a planar curve, click 
Planar Curve. The active datum plane is the reference plane by default.
Planar Curve. The active datum plane is the reference plane by default.3. To change the reference plane, click the References tab, click the Reference collector, and select a new reference plane.
4. To offset the curve from the active plane, type a value in the Offset box on the References tab. Optionally, click 
to export the offset value for editing outside of Style.
to export the offset value for editing outside of Style.5. Define points for the curve. You can use control points and interpolation points.
6. To define the curve using control points, click 
Control Points.
Control Points.7. To set the curve degree, type or select a value in the Degree box.
8. Closed curves are created as periodic. To change the closed curve to nonperiodic, click 
Periodic Curve. Click Periodic Curve again to change the curve back to periodic.
Periodic Curve. Click Periodic Curve again to change the curve back to periodic. | For periodic curves, the value for the curve degree must be an odd number. When a curve of an even-numbered degree is changed to periodic, the degree increases by one. |
9. To create a curve that is symmetric:
a. Click 
Symmetrical Curve.
Symmetrical Curve.b. Click the Plane collector, and then select a datum plane to define the symmetry plane for the curve.
c. If required, to reverse the curve direction, right-click the curve and choose Flip Curve Direction.
10. To maintain the curve shape during edits by moving the free points in proportion to the soft points, click the Options tab, and select the Proportional Update check box.
| | A curve without proportional update only changes shape at the soft point during edits. |
11. Click 
OK.
OK.