由网友(心口朱砂是你゛)分享简介：我有我的九年级的科学公正的项目的问题，我需要一些帮助。对于我的项目，我想打一个交通仿真，但有一点是给我麻烦...... I have a question for my ninth grade science fair project and I need some help. For my project I wa...

我有我的九年级的科学公正的项目的问题，我需要一些帮助。对于我的项目，我想打一个交通仿真，但有一点是给我麻烦......

I have a question for my ninth grade science fair project and I need some help. For my project I want to make a traffic simulator, but one thing is giving me trouble...

让我们说，我有一个行的坐标（25,35 45,65，30,85 - 这将是两部分的线）。我需要移动一个点（车）沿着这条线以恒定的距离每帧。我怎样才能做到这一点？

Let's say that I have the coordinates of a line (25,35 45,65, 30,85 - It would be a two part line). I need to move a point (car) along that line at a constant distance every frame. How can I do this?

谢谢，C.Ruhl

推荐答案

考虑行（25,35 45,65）。从开始到结束时的矢量为（20，30）。要移动一个点（x，y）的那个方向，我们可以只添加矢量：

Consider the line (25,35 45,65). The vector from the beginning to the end is (20, 30). To move a point (x,y) in that direction, we could just add that vector:

V =（20，30） （X，Y）=>（X + 20，Y + 30）。

V = (20, 30) (x,y) => (x+20, y+30).

如果我们开始在该行的开始，我们将到达终点。 但是，这是太大的一步。我们想要的东西，但更小的在同一方向的，所以我们乘以向量，比方说，0.1

If we start at the beginning of the line, we'll arrive at the end. But that's too big a step. We want something smaller but in the same direction, so we multiply the vector by, say, 0.1:

V =（2，3） （X，Y）=>（X + 2，Y + 3）=>（x + 4开始，Y + 6）=> ...

V = (2, 3) (x,y) => (x+2, y+3) => (x+4, y+6) => ...

这是方便的标准化，那就是让其长度为1，这是我们做的由它的长度划分：

It's convenient to normalize, that is to make its length 1, which we do by dividing by its length:

V => V / | V | =（2,3）/的sqrt（2 2 + 3 2 ）=（7.21，10.82）

V => V/|V| = (2,3)/sqrt(22 + 32) = (7.21, 10.82)

然后，你可以乘上任何一步你想要的大小。

Then you can just multiply that by whatever step size you want.