Draft Arc 3Points/zh-cn

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样条与底图贝叶斯曲线工具来近似地逼近一条圆弧.



如何使用

 * 1) 按下按钮，或先按键再按键.
 * 2) 在3D视图中点击第一个点，或输入一个 坐标并按下按钮.
 * 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, or  after one point to constrain the following point on the given axis.
 * To enter coordinates manually, simply enter the numbers, then press between each X, Y and Z component.
 * You can press the button when you have entered the desired values to insert the point.
 * Press 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.
 * Hold while drawing to constrain your next point horizontally or vertically in relation to the previous one.
 * Press or the  button to abort the current command.

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
Draft API 与 FreeCAD Scripting Basics.

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:


 * Creates an object from the given  list.
 * If a is given, the center of the circular arc will be moved to this place. See Placement for more information.
 * If is, the arc will make a face, that is, it will appear filled.
 * If is given, it is a, 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,


 * If is given, it is a string defining a type of mapping, for example, ,  , etc. See Part Attachment for more information.
 * If is, the arc created will be a simple Part Feature, not a complex Draft object.

Example:

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