 # Curves Tab

Note: Select a link to "jump" to the desired Curves tab group.

## Create Curves Curve by Points Used to place a B-spline curve. Curve by Tangents Used to create a B-spline curve that passes through a set of points while maintaining user-defined tangent directions at those points. Composite Curve Used to place a composite curve, which can have line strings, arcs, or Bézier curves (fourth order B-spline curves with four poles) as components. Interpolation by Arcs Used to place or construct a complex chain of arcs that passes through a given set of points. Conic Curve Used to place a conic section — a hyperbola, parabola, or partial ellipse — as a third-order uniform rational B-spline curve with three poles. Spiral Used to place a transitional spiral as a B-spline curve. Helix (3D only) Used to place a helix (3D B-spline curve).

## Modify Curves Extend Curve Used to extend an element (line, line string, arc, ellipse, complex chain or B-spline curve) by a certain scale. Blend Curve Used to construct a B-spline curve between two elements (lines, line strings, arcs, ellipses, complex chains, complex shapes, or B-spline curves) that consists of the trimmed original elements and a transition curve connecting them. Curve Handlebar Used to modify the shape of a B-spline curve by interactively adjusting the location of a point on the curve, or the tangency direction at that point. Edit Kinks Used to insert or remove kink points on a B-spline curve. Edit Knots Used to insert or remove knots. Edit Nodes Used to insert or move nodes on B-spline curves. Edit Weights Used to select a B-spline curve, then a control point to modify its weight using the text field input or the slider. Split Curves Used to split a B-spline curve into a defined number of sections by any one of three methods. Edit Control Points Used to show or hide the control points for a B-spline curve, or to change the number of control points for the curve.

## Curve Utilities Flatten Used to flatten or project a curve-type element, such as a line string, complex chain, complex shape, or B-spline curve, into a specified plane. Facet Used to convert curved elements and B-spline curves to lines, a line string, a stream curve, arcs, or points. Change Direction Used to reverse an element's (line, line string, arc, ellipse, complex chain, complex shape, curve, or B-spline curve) direction. Change Curve Order Used to change the order of a B-spline curve. Change Curve Closure Used to set the closure of a B-spline curve to Open or Closed. Convert to Curve Used to convert an element (line, line string, arc, ellipse, complex chain, or complex shape.) to a B-spline curve with the same shape. Extract Points Used to graphically and numerically evaluate the attributes of a B-spline curve (tangents, curvatures, and inflection points) at given locations on the curve. Curve by Formula Opens the Curve by Formula dialog, which is used to place any conceivable planar curve as a B-spline curve or a line string, based on a mathematical formula, from a library of pre-defined curves or by defining a custom formula. Match Settings Used to change the to the B-spline attributes of a B-spline curve in the design. Rebuild Used to clean up a B-spline curve that has a large number of control points (poles), like those sometimes imported from other systems. Fair Curvature Used to minimize the curvature variation of a B-spline curve.