Sketcher CreateEllipseByCenter/zh-cn: Difference between revisions

From FreeCAD Documentation
(Created page with "Image:Sketcher_EllipseExample1.png‎|thumb|none|500px|绘制椭圆所选中的一系列点以带数字的黄色箭头表示。C为中点,a - 长半轴,b - 短半轴,F...")
(Created page with "==如何使用==")
Line 18: Line 18:
[[Image:Sketcher_EllipseExample1.png‎|thumb|none|500px|绘制椭圆所选中的一系列点以带数字的黄色箭头表示。C为中点,a - 长半轴,b - 短半轴,F1、F2为焦点。]]
[[Image:Sketcher_EllipseExample1.png‎|thumb|none|500px|绘制椭圆所选中的一系列点以带数字的黄色箭头表示。C为中点,a - 长半轴,b - 短半轴,F1、F2为焦点。]]


==How to use==
==如何使用==


* Invoke the command by clicking a toolbar button, picking the menu item, or by using keyboard shortcut (needs to be assigned first in [[Interface Customization]]).
* Invoke the command by clicking a toolbar button, picking the menu item, or by using keyboard shortcut (needs to be assigned first in [[Interface Customization]]).

Revision as of 08:32, 20 July 2019

Sketcher Create Ellipse by center

Menu location
Sketch → Sketcher geometries → Create ellipse by center
Workbenches
Sketcher
Default shortcut
None
Introduced in version
0.15
See also
Sketcher Ellipse by 3 Points, Sketcher Circle, Sketcher Arc of Ellipse

描述

本工具会根据用户拾取的三个点:中点、长半轴点与短半轴点来绘制一个椭圆。 在开启此工具时,鼠标指针会变为一个附有红色椭圆图标的白色十字。同时还会将当前的指针坐标实时显现在侧。

绘制椭圆所选中的一系列点以带数字的黄色箭头表示。C为中点,a - 长半轴,b - 短半轴,F1、F2为焦点。

如何使用

  • Invoke the command by clicking a toolbar button, picking the menu item, or by using keyboard shortcut (needs to be assigned first in Interface Customization).
  • First click in 3D view sets ellipse center. Second click sets the first radius and orientation of the ellipse. Third click sets the other radius (the distance from the line defined by first two clicks is the second radius).
  • After the third click, the ellipse is created, together with a set of construction geometry aligned to it (major diameter, minor diameter, two foci). The construction geometry can be manually deleted if not needed, and recreated later. See Internal Alignment Constraint and Sketcher Show Hide Internal Geometry.
  • Pressing ESC or clicking the right mouse button cancels the function.

Peculiarities

  • Major and minor axes of ellipses are strict and cannot be swapped by resizing the ellipse. This is a consequence of the solver parametrization used (center (x,y), focus1 (x,y) and minor radius length (b)) and the same strict behavior of OpenCascade. The ellipse must be rotated to swap the axes.
  • Ellipse can function as a circle when its major and minor diameter lines are deleted, and one of the foci is constrained to coincide with the center. But radius constraint won't work on such a circle.
  • Moving the ellipse by edge is the same as moving ellipse's center.