草图工作台中的根据中点创建椭圆工具
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Sketcher
User documentation
Outdated translations are marked like this.
通过中心创建椭圆 |
菜单位置 |
---|
Sketch → 草图几何体 → 通过中心创建椭圆 |
所属工作台 |
Sketcher |
默认快捷键 |
G E E |
版本介紹 |
0.15 |
参阅 |
通过三点创建椭圆, 创建圆, 创建椭圆弧 |
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。
The sequence of clicks is indicated by yellow arrows with numbers.
C is the center, a the major diameter, b the minor diameter, F1 and F2 are foci.
如何使用
- 通过点击工具按钮,选择对应菜单项或借助键盘快捷键(首先需要在Interface Customization中为之分配快捷键)来调用对应绘制椭圆命令。
- 在3D视图中第一次点击所设置的是椭圆的中心。第二次点击所设置的是椭圆的第一个半径及其方向。第三次点击所设置的是另一种半径(前两次点击所定义的直线至第三次点击位置的距离即为第二个半径)。
- 第三次点击后,椭圆就创建好了,与之共存的还有一系列对齐于它的构造几何对象(长轴、短轴、两个焦点)如果不需要这些构造几何对象,可将其手动删除,以后还可以重新创建。参见在草图工作台中显示隐藏的内部几何图形。
- 按ESC键或单击鼠标右键来退出此功能。
Peculiarities
特性
- 长轴与短轴是严格界定的,调整椭圆时并不能交换两者。这是求解器参数化椭圆时所用的信息(中点(x,y)、焦点focus1(x,y)以及短半轴长度(b)),OpenCascade也严格遵循相同的行为。因此,必须通过旋转的方式来交换椭圆的两轴。
- 当椭圆的长轴与短轴被删,且焦点之一被约束为与中点重合,则该椭圆将变为一个圆。但是此圆中的半径约束却无法生效。
- 通过拖动边来移动椭圆与移动椭圆的中点效果相同。
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