Curva de Bezier

This page is a translated version of the page Draft BezCurve and the translation is 29% complete.
Outdated translations are marked like this.

Draft BezCurve

Drafting → Bézier tools → Bézier curve
Workbenches
Draft, Arch
Default shortcut
B Z
Introduced in version
0.14
Draft CubicBezCurve, Draft BSpline

Descrição

The Draft BezCurve command creates a Bézier curve from several points.

The command creates a single Bézier curve with a DadosDegree that is `number_of_points - 1`. It can be transformed into a piecewise Bézier curve by reducing this property.

The Draft BezCurve and the Draft CubicBezCurve commands use control points to define the position and curvature of the spline. The Draft BSpline command, on the other hand, specifies the exact points through which the curve will pass.

Bézier curve defined by multiple points

Utilização

See also: Draft Tray, Draft Snap and Draft Constrain.

1. There are several ways to invoke the command:
• Press the button.
• Select the Drafting → Bézier tools → Bézier curve option from the menu.
• Use the keyboard shortcut: B then Z. introduced in version 0.20
2. The Bézier curve task panel opens. See Options for more information.
3. Pick the first point in the 3D view, or type coordinates and press the Enter point button.
4. Pick additional points in the 3D view, or type coordinates and press the Enter point button.
5. Press Esc or the Close button to finish the command.

Opções

The single character keyboard shortcuts available in the task panel can be changed. See Draft Preferences. The shortcuts mentioned here are the default shortcuts.

• To manually enter coordinates enter the X, Y and Z component, and press Enter after each. Or you can press the Enter point button when you have the desired values. It is advisable to move the pointer out of the 3D view before entering coordinates.
• Press R or click the Relative checkbox to toggle relative mode. If relative mode is on, coordinates are relative to the last point, if available, else they are relative to the coordinate system origin.
• Press G or click the Global checkbox to toggle global mode. If global mode is on, coordinates are relative to the global coordinate system, else they are relative to the working plane coordinate system. introduced in version 0.20
• Press L or click the Filled checkbox to toggle filled mode. If filled mode is on, the created curve will have DadosMake Face set to `true` and will have a filled face, provided it is closed and does not self-intersect. Note that a self-intersecting curve with a face will not display properly, for such a curve DadosMake Face must be set to `false`.
• Press T or click the Continue checkbox to toggle continue mode. If continue mode is on, the command will restart after using Finish or Close, or after creating a closed curve by snapping to the first point of the curve, allowing you to continue creating curves.
• Press / or the Undo button to undo the last point.
• Press A or the Finish button to finish the command and leave the curve open.
• Press O or the Close button to finish the command and close the curve. A closed curve can also be created by snapping to the first point of the curve.
• Press W or the Wipe button to delete the segments already placed, but keep working from the last point.
• Press U or the button to adjust the current working plane in the orientation defined by the last and the previous point.
• Press S to switch Draft snapping on or off.
• Press Esc or the Close button to finish the command.

Notas

• A Draft BezCurve can be edited with the Draft Edit command.
• OpenCascade, and therefore FreeCAD, does not support Bézier curves of degrees larger than 25. This should not be a problem in practice, as most users typically use Bézier curves of degrees 3 to 5.

Preferências

See also: Preferences Editor and Draft Preferences.

• To change the number of decimals used for the input of coordinates: Edit → Preferences... → General → Units → Units settings → Number of decimals.
• To change the initial value of filled mode: Edit → Preferences... → Draft → General settings → Draft tools options → Fill objects with faces whenever possible. Changing the filled mode in a task panel will override this preference for the current FreeCAD session.

A Draft BezCurve object is derived from a Part Part2DObject and inherits all its properties. It also has the following additional properties:

Data

Draft

• DadosArea (`Area`): (read-only) specifies the area of the face of the curve. The value will be `0.0` if DadosMake Face if `false` or the face cannot be created.
• DadosClosed (`Bool`): specifies if the curve is closed or not. If the curve is initially open this value is `false`, setting it to `true` will draw a segment to close the curve. If the curve is initially closed this value is `true`, setting it to `false` will remove the last segment and make the curve open.
• DadosContinuity (`IntegerList`): (read-only) specifies the continuity of the curve.
• DadosDegree (`Integer`): specifies the degree of the curve.
• DadosLength (`Length`): (read-only) specifies the total length of the curve.
• DadosMake Face (`Bool`): specifies if the curve makes a face or not. If it is `true` a face is created, otherwise only the perimeter is considered part of the object. This property only works if DadosClosed is `true` and if the curve does not self-intersect.
• DadosPoints (`VectorList`): specifies the control points of the curve in its local coordinate system.

Vista

Draft

• VistaArrow Size (`Length`): specifies the size of the symbol displayed at the end of the curve.
• VistaArrow Type (`Enumeration`): specifies the type of symbol displayed at the end of the curve, which can be `Dot`, `Circle`, `Arrow`, `Tick` or `Tick-2`.
• VistaEnd Arrow (`Bool`): specifies whether to show a symbol at the end of the curve, so it can be used as an annotation line.
• VistaPattern (`Enumeration`): specifies the Draft Pattern with which to fill the face of the closed curve. This property only works if DadosMake Face is `true` and if VistaDisplay Mode is `Flat Lines`.
• VistaPattern Size (`Float`): specifies the size of the Draft Pattern.

Scripting

To create a Draft Line use the `make_bezcurve` method (introduced in version 0.19) of the Draft module. This method replaces the deprecated `makeBezCurve` method.

```bezcurve = make_bezcurve(pointslist, closed=False, placement=None, face=None, support=None, degree=None)
bezcurve = make_bezcurve(Part.Wire, closed=False, placement=None, face=None, support=None, degree=None)
```
• Creates a `bezcurve` object with the given list of points, `pointslist`.
• Each point in the list is defined by its `FreeCAD.Vector`, with units in millimeters.
• Alternatively, the input can be a `Part.Wire`, from which points are extracted.
• If `closed` is `True`, or if the first and last points are identical, the curve is closed.
• If `placement` is `None` the curve is created at the origin.
• If `face` is `True`, and the curve is closed, the curve will make a face, that is, it will appear filled.

Example:

```import FreeCAD as App
import Draft

doc = App.newDocument()

p1 = App.Vector(0, 0, 0)
p2 = App.Vector(1000, 1000, 0)
p3 = App.Vector(2000, 0, 0)
p4 = App.Vector(1500, -2000, 0)

bezcurve1 = Draft.make_bezcurve([p1, p2, p3, p4], closed=True)
bezcurve2 = Draft.make_bezcurve([p4, 1.3*p2, p1, 4.1*p3], closed=True)
bezcurve3 = Draft.make_bezcurve([1.7*p3, 1.5*p4, 2.1*p2, p1], closed=True)

doc.recompute()
```