延伸的线段的特定距离 [英] Extend a line segment a specific distance

问题描述

我试图找到一种方法，通过一个特定的距离延长线段。例如，如果我有一个线段开始于10,10延伸至20,13，我想通过延长长度3我怎么计算的新端点。我可以通过开方（一^ 2 + B ^ 2）的长度在这个例子10.44，所以如果我想知道，从10,10新端点，其长度为13.44什么是计算速度最快的方法是什么？我也知道了斜坡，但不知道是否可以帮助我任何在这种情况下。

I am trying to find a way to extend a line segment by a specific distance. For example if I have a line segment starting at 10,10 extending to 20,13 and I want to extend the length by by 3 how do I compute the new endpoint. I can get the length by sqrt(a^2 +b^2) in this example 10.44 so if I wanted to know the new endpoint from 10,10 with a length of 13.44 what would be computationally the fastest way? I also know the slope but don't know if that helps me any in this case.

推荐答案

您可以找到您线段的单位矢量做到这一点，它扩展到您所需要的长度，然后翻译终点的线段与此载体。假设你的线段终点是 A 和 B ，并要经过终点 B （和 lenAB 是线段的长度）。

You can do it by finding unit vector of your line segment and scale it to your desired length, then translating end-point of your line segment with this vector. Assume your line segment end points are A and B and you want to extend after end-point B (and lenAB is length of line segment).

C.x = B.x + (B.x - A.x) / lenAB * length;
C.y = B.y + (B.y - A.y) / lenAB * length;

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