View source for Draft Arc 3Points/en

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{{Docnav
|[[Draft_Arc|Arc]]
|[[Draft_Circle|Circle]]
|[[Draft_Workbench|Draft]]
|IconL=Draft_Arc.svg
|IconR=Draft_Circle.svg
|IconC=Workbench_Draft.svg
}}

{{GuiCommand
|Name=Draft Arc 3Points
|MenuLocation=Drafting → Arc Tools → Arc From 3 Points<br>2D Drafting → Arc From 3 Points
|Workbenches=[[Draft_Workbench|Draft]], [[BIM_Workbench|BIM]]
|Shortcut={{KEY|A}} {{KEY|T}}
|Version=0.19
|SeeAlso=[[Draft_Arc|Draft Arc]], [[Draft_Circle|Draft Circle]]
}}

==Description==

The [[Image:Draft_Arc_3Points.svg|24px]] '''Draft Arc 3Points''' command creates a circular arc on the current [[Draft_SelectPlane|working plane]] from three points that define its circumference. The center and radius are calculated from these points.

A Draft Arc is in fact a [[Draft_Circle|Draft Circle]] with a {{PropertyData|First Angle}} that is not the same as its {{PropertyData|Last Angle}}.

[[Image:Draft_Arc_3Points_example.png|400px]]
{{Caption|Arc defined by three points on its circumference}}

==Usage==

See also: [[Draft_Tray|Draft Tray]], [[Draft_Snap|Draft Snap]] and [[Draft_Constrain|Draft Constrain]].

# There are several ways to invoke the command:
#* Press the {{Button|[[Image:Draft_Arc_3Points.svg|16px]] [[Draft_Arc_3Points|Arc From 3 Points]]}} button.
#* [[Draft_Workbench|Draft]]: Select the {{MenuCommand|Drafting → Arc Tools → [[Image:Draft_Arc_3Points.svg|16px]] Arc From 3 Points}} option from the menu.
#* [[BIM_Workbench|BIM]]: Select the {{MenuCommand|2D Drafting → [[Image:Draft_Arc_3Points.svg|16px]] Arc From 3 Points}} option from the menu.
#* Use the keyboard shortcut: {{KEY|A}} then {{KEY|T}}.
# The {{MenuCommand|Arc From 3 Points}} task panel opens. See [[#Options|Options]] for more information.
# Pick the first point in the [[3D_View|3D View]], or type coordinates and press the {{Button|[[Image:Draft_AddPoint.svg|16px]] Enter Point}} button.
# Pick the second point in the [[3D_View|3D View]], or type coordinates and press the {{Button|[[Image:Draft_AddPoint.svg|16px]] Enter Point}} button.
# Pick the third point in the [[3D_View|3D View]], or type coordinates and press the {{Button|[[Image:Draft_AddPoint.svg|16px]] Enter Point}} button.

==Options==

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

* To manually enter coordinates enter the X, Y and Z component, and press {{KEY|Enter}} after each. Or you can press the {{Button|[[Image:Draft_AddPoint.svg|16px]] Enter Point}} button when you have the desired values. It is advisable to move the pointer out of the [[3D_View|3D View]] before entering coordinates.
* Press {{KEY|R}} or click the {{MenuCommand|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 {{KEY|G}} or click the {{MenuCommand|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 [[Draft_SelectPlane|working plane]] coordinate system.
* Press {{KEY|N}} or click the {{MenuCommand|Continue}} checkbox to toggle continue mode. If continue mode is on, the command will restart after finishing, allowing you to continue creating arcs.
* Press {{KEY|S}} to switch [[Draft_Snap|Draft snapping]] on or off.
* Press {{KEY|Esc}} or the {{Button|Close}} button to abort the command.

==Notes==

* A Draft Arc can be edited with the [[Draft_Edit|Draft Edit]] command.

==Preferences==

See also: [[Preferences_Editor|Preferences Editor]] and [[Draft_Preferences|Draft Preferences]].

* If the {{MenuCommand|Edit → Preferences → Draft → General → Create Part primitives if possible}} option is checked, the command will create a non-editable [[Part_Feature|Part Feature]] instead of a Draft Circle.

==Properties==

See [[Draft_Circle#Properties|Draft Circle]].

==Scripting==

See also: [https://freecad.github.io/SourceDoc/ Autogenerated API documentation] and [[FreeCAD_Scripting_Basics|FreeCAD Scripting Basics]].

To create a Draft Arc by 3 points use the {{incode|make_arc_3points}} method of the Draft module:

{{Code|code=
arc = make_arc_3points(points, placement=None, face=False, support=None, map_mode="Deactivated", primitive=False)
}}

* Creates an {{incode|arc}} object from the given {{incode|points}} list.
* If a {{incode|placement}} is given, the center of the circular arc will be moved to this place. See [[Placement|Placement]] for more information.
* If {{incode|face}} is {{incode|True}}, the arc will make a face, that is, it will appear filled.
* If {{incode|support}} is given, it is a {{incode|LinkSubList}}, that is, a list indicating an object and a subelement of that object. This is used so that the object appears referenced to this support.
: For example: <code>support=[(obj, ("Face1"))]</code>.
* If {{incode|map_mode}} is given, it is a string defining a type of mapping, for example: <code>map_mode='FlatFace'</code>, <code>map_mode='ThreePointsPlane'</code>, etc. See [[Part_EditAttachment|Part EditAttachment]] for more information.
* If {{incode|primitive}} is {{incode|True}}, the arc created will be a simple [[Part_Feature|Part Feature]], not a complex Draft object.

Example:

{{Code|code=
import FreeCAD as App
import Draft

doc = App.newDocument()

points = [App.Vector(0, 0, 0),
          App.Vector(5, 10, 0),
          App.Vector(10, 0, 0)]

arc = Draft.make_arc_3points(points)

doc.recompute()
}}


{{Docnav
|[[Draft_Arc|Arc]]
|[[Draft_Circle|Circle]]
|[[Draft_Workbench|Draft]]
|IconL=Draft_Arc.svg
|IconR=Draft_Circle.svg
|IconC=Workbench_Draft.svg
}}

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