Draft BezCurve: Difference between revisions

From FreeCAD Documentation
(More information for the properties)
m (Added template)
(35 intermediate revisions by 4 users not shown)
Line 1: Line 1:
<languages/>
<languages/>
<translate>
<translate>
<!--T:24-->
{{Docnav|[[Draft_Facebinder|Facebinder]]|[[Draft CubicBezCurve|CubicBezCurve]]|[[Draft_Module|Draft]]|IconL=Draft_Facebinder.svg |IconC=Workbench_Draft.svg|IconR=Draft CubicBezCurve.svg }}

<!--T:14-->
<!--T:14-->
{{GuiCommand
{{GuiCommand
|Name=Draft BezCurve
|Name=Draft BezCurve
|Workbenches=[[Draft Module|Draft]], [[Arch Module|Arch]]
|Workbenches=[[Draft Module|Draft]], [[Arch Module|Arch]]
|MenuLocation=Draft → BezCurve
|MenuLocation=Draft → Bezier tools → BezCurve
|Shortcut=B Z
|Shortcut={{KEY|B}} {{KEY|Z}}
|SeeAlso=[[Draft Wire|Draft Wire]], [[Draft BSpline|Draft BSpline]]
|Version=0.14}}
|Version=0.14}}


Line 12: Line 16:


<!--T:2-->
<!--T:2-->
The BezCurve tool creates a [http://en.wikipedia.org/wiki/Bezier_curve Bezier Curve], or a piecewise Bezier curve, from several points in the current [[Draft SelectPlane|work plane]]. It uses the [[Draft Linestyle]] set on the [[Draft Tray]].
The {{Button|[[Image:Draft_BezCurve.png|16px]] [[Draft BezCurve|Draft BezCurve]]}} tool creates a [http://en.wikipedia.org/wiki/Bezier_curve Bezier Curve], or a piecewise Bezier curve, from several points. It uses the [[Draft Linestyle|Draft Linestyle]] set on the [[Draft Tray|Draft Tray]].


<!--T:15-->
The BezCurve tool curve uses {{Emphasis|control points}} to define the direction of the curve; on the other hand the [[Draft BSpline|Draft BSpline]] tool specifies the exact points through which the curve will go. To create exact circular or elliptical curves, use [[Draft Arc|Draft Arc]] and [[Draft Ellipse|Draft Ellipse]].

</translate>
[[Image:Draft_BezCurve_Example.png|400px]]
[[Image:Draft_BezCurve_Example.png|400px]]
<translate>
<!--T:16-->
{{Caption|Bezier curve defined by multiple control points}}


==How to use== <!--T:3-->
==Usage== <!--T:3-->


<!--T:17-->
# Press the {{Button|[[Image:Draft_BezCurve.png|16px]] [[Draft BezCurve]]}} button, or press {{KEY|B}} then {{KEY|Z}} keys.
# Press the {{Button|[[Image:Draft_BezCurve.png|16px]] [[Draft BezCurve|Draft BezCurve]]}} button, or press {{KEY|B}} then {{KEY|Z}} keys.
# Click a first point on the 3D view, or type a [[Draft_Coordinates|coordinate]] and press the {{Button|[[Image:Draft_AddPoint.svg|16px]] [[Draft_AddPoint|add point]]}} button.
# Click a first point on the 3D view, or type a [[Draft_Coordinates|coordinate]] and press the {{Button|[[Image:Draft_AddPoint.svg|16px]] [[Draft_AddPoint|add point]]}} button.
# Click additional points on the 3D view, or type a [[Draft_Coordinates|coordinate]] and press the {{Button|[[Image:Draft_AddPoint.svg|16px]] [[Draft_AddPoint|add point]]}} button.
# Click additional points on the 3D view, or type a [[Draft_Coordinates|coordinate]] and press the {{Button|[[Image:Draft_AddPoint.svg|16px]] [[Draft_AddPoint|add point]]}} button.
Line 24: Line 36:


<!--T:12-->
<!--T:12-->
The object is created as a single Bezier curve of degree {{incode|number_of_points - 1}}.
The object is created as a single Bezier curve of degree {{incode|number_of_points - 1}}. It can be transformed to a piecewise wire made of curves of a specified degree by changing its properties.


<!--T:18-->
The curve can be transformed to a piecewise wire made of curves of a specified degree by changing its properties.
The curve can be edited by double clicking on the element in the tree view, or by pressing the {{Button|[[Image:Draft Edit.svg|16px]] [[Draft Edit|Draft Edit]]}} button. Then you can move the points to a new position, or click {{Button|[[Image:Draft_AddPoint.svg|16px]] [[Draft_AddPoint|add point]]}} or {{Button|[[Image:Draft_DelPoint.svg|16px]] [[Draft_DelPoint|remove point]]}} and then click on the curve to add or remove points. You can also change the constraint type of each point.


=== Node constraints === <!--T:13-->
The control points of the Bezier curve can be edited by double clicking on the element in the tree view, or by pressing the {{Button|[[Image:Draft Edit.png|16px]] [[Draft Edit]]}} button.

<!--T:19-->
The segment endpoints can be constrained such that adjacent control points are tangent or symmetric to the segments at the endpoint.
First, start editing the curve, then pick one of the tools and then pick a point. Click again on the tool to deactivate it, so you can move the point.
* {{Button|[[Image:Draft_BezSharpNode.svg|32px]] sharp}} remove constraints on the points so the curve can have sharp corners.
* {{Button|[[Image:Draft_BezTanNode.svg|32px]] tangent}} force adjacent control points to be tangent.
* {{Button|[[Image:Draft_BezSymNode.svg|32px]] symmetric}} force adjacent control points to be tangent and equidistant.

===Limitations=== <!--T:11-->
* The Points property does not yet appear in the properties list.
* OpenCascade, and thus FreeCAD, does not support Bezier curves of degrees larger than 25. This should not be a problem in practice, as most users would typically use Bezier curves of degrees 3 to 5.


==Options== <!--T:4-->
==Options== <!--T:4-->
Line 42: Line 66:
* Press {{KEY|T}} or click the checkbox to toggle ''continue'' mode. If continue mode is on, the BezCurve tool will restart after you finish the curve, allowing you to draw another one without pressing the tool button again.
* Press {{KEY|T}} or click the checkbox to toggle ''continue'' mode. If continue mode is on, the BezCurve tool will restart after you finish the curve, allowing you to draw another one without pressing the tool button again.
* Press {{KEY|L}} or click the checkbox to toggle ''filled'' mode. If filled mode is on, a closed wire will create a filled face ({{PropertyData|Make Face}} {{TRUE}}); if not, the closed wire will not make a face ({{PropertyData|Make Face}} {{FALSE}}).
* Press {{KEY|L}} or click the checkbox to toggle ''filled'' mode. If filled mode is on, a closed wire will create a filled face ({{PropertyData|Make Face}} {{TRUE}}); if not, the closed wire will not make a face ({{PropertyData|Make Face}} {{FALSE}}).
:{{Emphasis|Note:}} the curve should not be filled if it intersects itself, as it won't create a proper face. If the curve is filled but no shape is visible, manually set {{PropertyData|Make Face}} to {{FALSE}} to see the curve.
* Press {{KEY|Ctrl}} while drawing to force [[Draft_Snap|snapping]] your point to the nearest snap location, independently of the distance.
* Press {{KEY|Shift}} while drawing to [[Draft_Constrain|constrain]] your next point horizontally or vertically in relation to the last one.
* Hold {{KEY|Ctrl}} while drawing to force [[Draft_Snap|snapping]] your point to the nearest snap location, independently of the distance.
* Hold {{KEY|Shift}} while drawing to [[Draft_Constrain|constrain]] your next point horizontally or vertically in relation to the last one.
* Press {{KEY|Ctrl}}+{{KEY|Z}} or press the {{button|[[Image:Draft UndoLine.png|12px]] [[Draft_UndoLine|Undo]]}} button to undo the last point.
* Press {{KEY|Ctrl}}+{{KEY|Z}} or press the {{button|[[Image:Draft UndoLine.png|12px]] [[Draft_UndoLine|Undo]]}} button to undo the last point.
* Press {{KEY|Esc}} or the {{button|Close}} button to abort the current command; curve segments already placed will remain.
* Press {{KEY|Esc}} or the {{button|Close}} button to abort the current command; curve segments already placed will remain.
Line 49: Line 74:
==Properties== <!--T:6-->
==Properties== <!--T:6-->


<!--T:7-->
=== Data === <!--T:20-->
* {{PropertyData|Degree}}: specifies the degree of the Bezier curve or the individual segments.
* {{PropertyData|Degree}}: specifies the degree of the Bezier curve or the individual segments.
* {{PropertyData|Closed}}: 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.
* {{PropertyData|Closed}}: 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.
* {{PropertyData|Make Face}}: 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 {{PropertyData|Closed}} is {{TRUE}}.
* {{PropertyData|Make Face}}: 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 {{PropertyData|Closed}} is {{TRUE}}.
:{{Emphasis|Note:}} do not set {{PropertyData|Make Face}} to {{TRUE}} if the curve intersects itself, as it won't create a proper face.
* {{PropertyData|Continuity}}: (read-only) when the curve is closed, indicates the continuity of the curve {{incode|[0]}}, or {{incode|[0,0]}}. Otherwise it's {{incode|[]}}.
* {{PropertyData|Continuity}}: (read-only) when the curve is closed, indicates the continuity of the curve {{incode|[0]}}, or {{incode|[0,0]}}. Otherwise it's {{incode|[]}}.


==Scripting== <!--T:8-->
=== View === <!--T:21-->
* {{PropertyView|Arrow Size}}: specifies the size of the symbol displayed at the end of the curve.
* {{PropertyView|Arrow Type}}: specifies the type of symbol displayed at the end of the curve, which can be dot, circle, arrow, and tick.
* {{PropertyView|End Arrow}}: specifies whether to show a symbol at the last point of the curve, so it can be used as an annotation line.
* {{PropertyView|Pattern}}: specifies a [[Draft Pattern|Draft Pattern]] with which to fill the face of the closed curve. This property only works if {{PropertyData|Make Face}} is {{TRUE}}, and if {{PropertyView|Display Mode}} is "Flat Lines".
* {{PropertyView|Pattern Size}}: specifies the size of the [[Draft Pattern|Draft Pattern]].


==Scripting== <!--T:8-->
{{Emphasis|See also:}} [[Draft API|Draft API]] and [[FreeCAD Scripting Basics|FreeCAD Scripting Basics]].


<!--T:9-->
<!--T:9-->
The BezCurve tool can by used in [[macros]] and from the python console by using the following function:
The BezCurve tool can be used in [[macros|macros]] and from the [[Python|Python]] console by using the following function:
</translate>
</translate>
{{Code|code=
{{Code|code=
makeBezCurve(pointslist,[closed],[placement],[support],[degree])
BezCurve = makeBezCurve(pointslist, closed=False, placement=None, face=None, support=None, degree=None)
BezCurve = makeBezCurve(Part.Wire, closed=False, placement=None, face=None, support=None, degree=None)
}}
}}
<translate>
<translate>

<!--T:10-->
<!--T:10-->
* Create a Bezier Curve object from the given list of vectors. Instead of a pointslist, you can also pass a Part Wire.
* Creates a {{incode|BezCurve}} object with the given list of points, {{incode|pointslist}}.
** Each point in the list is defined by its {{incode|FreeCAD.Vector}}, with units in millimeters.
** Alternatively, the input can be a {{incode|Part.Wire}}, from which points are extracted.
* If {{incode|closed}} is {{incode|True}}, or if the first and last points are identical, the curve is closed.
* If a {{incode|placement}} is given, it is used; otherwise the shape is created at the origin.
* If {{incode|face}} is {{incode|True}}, and the wire is closed, the wire will make a face, that is, it will appear filled.


<!--T:22-->
Example:
</translate>
</translate>
Example:
{{Code|code=
{{Code|code=
import FreeCAD,Draft
import FreeCAD, Draft

myFeature = Draft.makeBezCurve(Draft.makeBezCurve(points,False)
p1 = FreeCAD.Vector(0, 0, 0)
p2 = FreeCAD.Vector(1000, 1000, 0)
p3 = FreeCAD.Vector(2000, 0, 0)
p4 = FreeCAD.Vector(1500, -2000, 0)

BezCurve1 = Draft.makeBezCurve([p1, p2, p3, p4], closed=True)
BezCurve2 = Draft.makeBezCurve([p4, 1.3*p2, p1, 4.1*p3], closed=True)
BezCurve3 = Draft.makeBezCurve([1.7*p3, 1.5*p4, 2.1*p2, p1], closed=True)
}}
}}
<translate>
<translate>
==Contraining Nodes== <!--T:13-->
The segment endpoints in a piecewise Bezier Curve can be constrained such that adjacent control points are tangent or symmetric to the segments at the endpoint. This is done after object creation using {{KEY|[[Image:Draft Edit.png|16px]] [[Draft Edit]]}}.
* [[Image:Draft_BezSharpNode.svg|32px]] '''Sharp''' - remove constraints
* [[Image:Draft_BezTanNode.svg|32px]] '''Tangent''' - force adjacent control points to be tangent
* [[Image:Draft_BezSymNode.svg|32px]] '''Symmetric''' - force adjacent control points to be tangent and equi-distant


==Limitations== <!--T:11-->
<!--T:23-->
{{Docnav|[[Draft_Facebinder|Facebinder]]|[[Draft CubicBezCurve|CubicBezCurve]]|[[Draft_Module|Draft]]|IconL=Draft_Facebinder.svg |IconC=Workbench_Draft.svg|IconR=Draft CubicBezCurve.svg }}
* This tool is not available before FreeCAD version 0.14

* The Points Property does not yet appear in the properties list.
<!--T:25-->
* OpenCascade does not support Bezier Curve with degree > 25. This should not be a problem in practice.
</translate>
{{Draft Tools navi}}
{{Draft Tools navi}}

<!--T:26-->
{{Userdocnavi}}
{{Userdocnavi}}
</translate>
{{clear}}
{{clear}}

Revision as of 18:03, 29 January 2020

Draft BezCurve

Menu location
Draft → Bezier tools → BezCurve
Workbenches
Draft, Arch
Default shortcut
B Z
Introduced in version
0.14
See also
Draft Wire, Draft BSpline

Description

The Draft BezCurve tool creates a Bezier Curve, or a piecewise Bezier curve, from several points. It uses the Draft Linestyle set on the Draft Tray.

The BezCurve tool curve uses control points to define the direction of the curve; on the other hand the Draft BSpline tool specifies the exact points through which the curve will go. To create exact circular or elliptical curves, use Draft Arc and Draft Ellipse.

Bezier curve defined by multiple control points

Usage

  1. Press the Draft BezCurve button, or press B then Z keys.
  2. Click a first point on the 3D view, or type a coordinate and press the add point button.
  3. Click additional points on the 3D view, or type a coordinate and press the add point button.
  4. Press Esc or the Close button, or double-click the last point to complete the edition.

The object is created as a single Bezier curve of degree number_of_points - 1. It can be transformed to a piecewise wire made of curves of a specified degree by changing its properties.

The curve can be edited by double clicking on the element in the tree view, or by pressing the Draft Edit button. Then you can move the points to a new position, or click add point or remove point and then click on the curve to add or remove points. You can also change the constraint type of each point.

Node constraints

The segment endpoints can be constrained such that adjacent control points are tangent or symmetric to the segments at the endpoint. First, start editing the curve, then pick one of the tools and then pick a point. Click again on the tool to deactivate it, so you can move the point.

  • sharp remove constraints on the points so the curve can have sharp corners.
  • tangent force adjacent control points to be tangent.
  • symmetric force adjacent control points to be tangent and equidistant.

Limitations

  • The Points property does not yet appear in the properties list.
  • OpenCascade, and thus FreeCAD, does not support Bezier curves of degrees larger than 25. This should not be a problem in practice, as most users would typically use Bezier curves of degrees 3 to 5.

Options

  • Press A or the Finish button to finish the curve, leaving it open.
  • Press O or the Close button to close the curve, that is, a segment will be added from the last point to the first one to form a face. At least four points, a curve of degree three, are required to form a face.
  • Press W or the Wipe button to remove the curve segments already placed, but keep editing the curve from the last point.
  • Press U or the Set WP button to adjust the current working plane in the orientation of the last point.
  • Press X, Y or Z after a point to constrain the next point on the given axis.
  • To enter coordinates manually, simply enter the numbers, then press Enter between each X, Y and Z component.
  • Press R or click the checkbox to toggle relative mode. If relative mode is on, the coordinates of the next point are relative to the last one; if not, they are absolute, taken from the origin (0,0,0).
  • Press T or click the checkbox to toggle continue mode. If continue mode is on, the BezCurve tool will restart after you finish the curve, allowing you to draw another one without pressing the tool button again.
  • Press L or click the checkbox to toggle filled mode. If filled mode is on, a closed wire will create a filled face (DataMake Face true); if not, the closed wire will not make a face (DataMake Face false).
Note: the curve should not be filled if it intersects itself, as it won't create a proper face. If the curve is filled but no shape is visible, manually set DataMake Face to false to see the curve.
  • Hold Ctrl while drawing to force snapping your point to the nearest snap location, independently of the distance.
  • Hold Shift while drawing to constrain your next point horizontally or vertically in relation to the last one.
  • Press Ctrl+Z or press the Undo button to undo the last point.
  • Press Esc or the Close button to abort the current command; curve segments already placed will remain.

Properties

Data

  • DataDegree: specifies the degree of the Bezier curve or the individual segments.
  • DataClosed: 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.
  • DataMake Face: 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 DataClosed is true.
Note: do not set DataMake Face to true if the curve intersects itself, as it won't create a proper face.
  • DataContinuity: (read-only) when the curve is closed, indicates the continuity of the curve [0], or [0,0]. Otherwise it's [].

View

  • ViewArrow Size: specifies the size of the symbol displayed at the end of the curve.
  • ViewArrow Type: specifies the type of symbol displayed at the end of the curve, which can be dot, circle, arrow, and tick.
  • ViewEnd Arrow: specifies whether to show a symbol at the last point of the curve, so it can be used as an annotation line.
  • ViewPattern: specifies a Draft Pattern with which to fill the face of the closed curve. This property only works if DataMake Face is true, and if ViewDisplay Mode is "Flat Lines".
  • ViewPattern Size: specifies the size of the Draft Pattern.

Scripting

See also: Draft API and FreeCAD Scripting Basics.

The BezCurve tool can be used in macros and from the Python console by using the following function:

BezCurve = makeBezCurve(pointslist, closed=False, placement=None, face=None, support=None, degree=None)
BezCurve = makeBezCurve(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 a placement is given, it is used; otherwise the shape is created at the origin.
  • If face is True, and the wire is closed, the wire will make a face, that is, it will appear filled.

Example:

import FreeCAD, Draft

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

BezCurve1 = Draft.makeBezCurve([p1, p2, p3, p4], closed=True)
BezCurve2 = Draft.makeBezCurve([p4, 1.3*p2, p1, 4.1*p3], closed=True)
BezCurve3 = Draft.makeBezCurve([1.7*p3, 1.5*p4, 2.1*p2, p1], closed=True)