# Curves

**(Available in all TurboCAD Variants)**

**Default UI Menu:** Draw/Curve

Ribbon UI Menu:

Tools for drawing splines, Bezier curves, sketches, and revision clouds. You can display the **Curve** toolbar by right-clicking in any toolbar area and selecting **Curve**.

**Autoshape**

**Default UI Menu:** Draw/Curve/Autoshape

Ribbon UI Menu:

The Autoshape tool allows you to quickly create standard shapes just by sketching. The sketched shape will automatically recompose into a standard object depending on the shape of the sketch. The objects include: Lines, Polylines, Rectangles, Polygons, Triangles Arcs, Circles, Ellipses, **Ellipse / Circles** If the sketch closely approximates a elliptical path an ellipse will be generated. If the radii of the computed ellipse are almost equal, then a circle is drawn. If the sketch closely approximates a circular path but is open an arc will be generated.

**Line** A single quick dash will result in a line. **Polyline** If the end points are closely located the resulting polyline will be closed. If the angle between the nearest computed line segments is close to to 90 degrees, right angle is created. A closed polyline with 3 points becomes a triangular Polygon. A closed polyline with 4 points becomes a rectangular Polygon. **Bezier Curve** If the sketch does not approximate a regular shape a Bezier curve will be created. The curve can be closed or open.

**Curve Properties**

Curve properties can be set on the **Curves** page of the **Properties** window. **Number of segments between adjacent control points:** Curves are composed of many small line segments drawn between control points. A high number of segments will yield a smoother curve; a low number will make the curve appear more jointed.

**High number of segments** **Low number of segments** **Bezier Curve** **Spline Curve** **Bezier Curve**

**Options:** If the curve is a Bezier curve, the following options are available: **Show additional control points:** Additional control points will be displayed when **Edit Node** mode is active (see Edit Tool and Editing Splines and Bezier Curves ). This also enables the **Keep the Curve** **Smooth** **option**.

**Regular control points in Edit Node mode**

**Additional control points in Edit Node mode** **Keep the curve smooth:** If checked, the additional control points at each node remain linear, so that no sharp corners can be created at a node. If not checked, you can move each additional node independently.

**Keep Curves Smooth - additional nodes remain linear**

**Keep Curves Smooth disabled**

**Warning:** Modifying tools such as **Split** or **Trim** may alter a curve drastically, because the curve loses the influence of deleted control points.

**Spline Curve Options:** The degree value creates a spline of n-th order, which affects the spline smoothness. **Show Frame:** If checked, a polyline frame will be displayed connecting the curve's control points. This provides visual feedback about how the curve is drawn.

**Revision Cloud**

**Default UI Menu:** Draw/Curve/Revision Cloud

Ribbon UI Menu:

Creates uniform revision clouds. These are most commonly used in Paper Space, but the tool is available in Model Space as well.

- Before selecting the start point, select
**Number of segments**from the local menu. The default number is 1, and each segment consists of two arcs. - Select the start and endpoints of the first segment.

- Continue selecting points for more segments.

- When finished, select
**Finish**(Alt+F) from the local menu, or select**Close**(Alt+C) to join the endpoints.

**Sketch**

**Default UI Menu:** Draw/Curve/Sketch

Ribbon UI Menu:

Creates a freehand drawing.

- Press and hold the mouse button to draw a freehand curve. Release the mouse when finished.

- As long as the tool is still active, you can continue drawing new curves.

**Splines and Bezier Curves**

These three tools each use a series of points to create a curve.

**Spline by Control Points**

**Default UI Menu:** Draw/Curve/By Control Points

Ribbon UI Menu:

**Spline by Fit Points**

**Default UI Menu:** Draw/Spline by Fit Points

Ribbon UI Menu:

**Bezier**

**Default UI Menu:** Draw/Curve/Bezier

Ribbon UI Menu:

For **Spline by Control Points**, the points act as a guide for the curve; the spline does not actually pass through all of the points. **For Spline by Fit Points** and **Bezier**, the curve does pass through each point. These two tools produce similar results; the main difference is the algorithm behind them, and how they are edited.

**Note:** To create splines in 3D, 3D Spline by Fit Points The three curves will be shown for this series of points:

Select the control points in the desired order. You can also enter the length and angle between points in the Inspector Bar. After selecting the last point, select **Finish** from the local menu or press Alt+F. You can also double-click the last point.

Spline by Control Points

Spline by Fit Points

Bezier

If you want to close the curve, select **Close** from the local menu instead of **Finish**.

Closed Spline by Control Points

**Closed Spline by Fit Points** Once created, you can use the **Edit** **Tool** to change the shape of a spline and add knots. See Editing Splines and Bezier Curves

**Tip:** You can change a spline into a Bezier curve, and vice-versa, by opening the **Properties** window and editing the **Curves** page. If you change a Bezier curve into a spline, it will be a **Spline by Control Points**. You can also convert 2D objects into a Bezier curve.