我想用clipper库剪辑平行线 [英] I want to clip parallel lines with clipper library

问题描述

我使用C ++的限幅器库。

I想要用多边形剪切平行线。

看下面的代码。

I use clipper library with C++.
I want to clip parallel lines with a polygon.
look below code.

Paths subj(2), clip(1), solution;
subj[0] <<IntPoint(0, 100) << IntPoint(100, 100);
subj[1] <<IntPoint(0, 50) << IntPoint(100, 50);
clip[0] <<IntPoint(30,0) << IntPoint(35,200) <<IntPoint(40,210) << IntPoint(45,40);
Clipper c;
c.AddPaths(subj, ptSubject, true);
c.AddPaths(clip, ptClip, true);
c.Execute(ctIntersection, solution, pftNonZero, pftNonZero);

但是解决方案的大小是执行以下指令后为零

c.Execute（ctIntersection，solution，pftNonZero，pftNonZero）。

为什么？问题在哪里？

but size of solution is zero after execute below instruction
c.Execute(ctIntersection, solution, pftNonZero, pftNonZero).
for what? problem is where?

推荐答案

虽然你发布的链接不起作用，但我能在这里找到这个库： http://www.angusj.com/delphi/clipper.php [ ^ ]。在此页面上： http：//www.angusj。 com / delphi / clipper / documentation / Docs / Units / ClipperLib / Classes / Clipper / Methods / Execute.htm [ ^ ]文档说明

Although the link you posted didn't work, I was able to find the library here: http://www.angusj.com/delphi/clipper.php[^]. On this page: http://www.angusj.com/delphi/clipper/documentation/Docs/Units/ClipperLib/Classes/Clipper/Methods/Execute.htm[^] the documentation states that

Quote：

当打开路径传递给Clipper对象时，用户必须使用PolyTree对象作为解决方案参数，否则将引发异常。

when open paths are passed to a Clipper object, the user must use a PolyTree object as the solution parameter, otherwise an exception will be raised.

因此，您必须将路径定义为封闭路径，或者您应将解决方案定义为 PolyTree 而不是使用路径类型。

我的路径（平行线）是打开的，所以我不能用这个库做这个工作。看看这个链接。

我改了线条到三角形，然后我剪辑它们。

当我想绘制它们时，我画平行线。

My paths(parallel lines) are open, so I can't do this work with this library. look this link.
I changed lines to triangles and then I clip their.
when I want to draw their, just I draw parallel lines.

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