底图三圆周点绘弧

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This page is a translated version of the page Draft Arc 3Points and the translation is 40% complete.
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Draft Arc 3Points.svg Draft Arc 3Points

Menu location
Draft → Arc 3 points
Workbenches
Draft, Arch
Default shortcut
A T
Introduced in version
0.19
See also
Draft Arc, Draft Circle, Draft Ellipse


描述

底图三圆周点绘弧工具通过输入4个点:中点、半径、第一个点、最后一点,或拾取的切线,或上述若干组合,在当前的工作平面上创建一条圆弧。它将根据Draft Tray中的Draft Linestyle设置来创建对应圆弧。

除了添加起始角度与终止角度这两个参数之外,本工具的工作方式与底图圆形工具相同。要绘制椭圆弧,可借助底图椭圆工具。另外,您也可以通过底图B样条底图贝叶斯曲线工具来近似地逼近一条圆弧。

Draft Arc 3Points example.png

根据圆周上的3个点而定义的弧


如何使用

  1. 按下Draft Arc 3Points.svg Draft Arc 3Points按钮,或先按A键再按T键。
  2. 在3D视图中点击第一个点,或输入一个 坐标并按下Draft AddPoint.svg add point按钮。
  3. 在3D视图中点击第二个点,或输入一个半径值。
  4. 在3D视图中点击第三个点,或输入一个起始角度。

选项

  • Press X, Y or Z after one point to constrain the following point on the given axis.
  • To enter coordinates manually, simply enter the numbers, then press Enter between each X, Y and Z component.
    • You can press the Draft AddPoint.svg add point button when you have entered the desired values to insert the point.
  • Press R or click the checkbox to toggle relative mode. If relative mode is on, the coordinates of the following point are relative to the previous one; if not, they are absolute, taken from the origin (0, 0, 0).
  • Hold Shift while drawing to constrain your next point horizontally or vertically in relation to the previous one.
  • Press Esc or the Close button to abort the current command.

属性

属性

弧对象享有Draft Circle中的所有属性,但是有些属性仅对圆形而言才有意义。

脚本

参见: Draft APIFreeCAD Scripting Basics

See also: Draft API and FreeCAD Scripting Basics.

The Arc by 3 points tool can be used in macros and from the Python console by using the following function:

arc = make_arc_3points(points, placement=None, face=False, support=None, map_mode="Deactivated", primitive=False)
  • Creates an arc object from the given points list.
  • If a placement is given, the center of the circular arc will be moved to this place. See Placement for more information.
  • If face is True, the arc will make a face, that is, it will appear filled.
  • If support is given, it is a 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, support=[(obj, ("Face1"))]
  • If map_mode is given, it is a string defining a type of mapping, for example, map_mode='FlatFace', map_mode='ThreePointsPlane', etc. See Part Attachment for more information.
  • If primitive is True, the arc created will be a simple Part Feature, not a complex Draft object.

Example:

import FreeCAD as App
import draftobjects.arc_3points as arc3

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

arc = arc3.make_arc_3points(points)

doc.recompute()

Note: internally this function still uses Draft.makeCircle, so the object created is the same as the one created by Circle and Arc.

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