Java 2D:将点P移至距另一个点一定距离的位置? [英] Java 2D: Moving a point P a certain distance closer to another point?

问题描述

将Point2D.Double移近另一个Point2D.Double的最佳方法是什么?

What is the best way to go about moving a Point2D.Double x distance closer to another Point2D.Double?

试图进行编辑，但是为了维护而去了.不，这不是功课

Tried to edit, but so went down for maintenance. No this is not homework

我需要将飞机(A)移向跑道(C)的尽头，并指向正确的方向(角度a).

I need to move a plane (A) towards the end of a runway (C) and point it in the correct direction (angle a).

替代文字http://img246.imageshack.us/img246/9707/planec. png

到目前为止，这里是我所拥有的，但是似乎很混乱，执行这样的事情的通常方法是什么?

Here is what I have so far, but it seems messy, what is the usual way to go about doing something like this?

    //coordinate = plane coordinate (Point2D.Double)
    //Distance = max distance the plane can travel in this frame

    Triangle triangle = new Triangle(coordinate, new Coordinate(coordinate.x, landingCoordinate.y),  landingCoordinate);

    double angle = 0;

    //Above to the left
    if (coordinate.x <= landingCoordinate.x && coordinate.y <= landingCoordinate.y)
    {
        angle = triangle.getAngleC();
        coordinate.rotate(angle, distance);
        angle = (Math.PI-angle);
    }
    //Above to the right
    else if (coordinate.x >= landingCoordinate.x && coordinate.y <= landingCoordinate.y)
    {
        angle = triangle.getAngleC();
        coordinate.rotate(Math.PI-angle, distance);
        angle = (Math.PI*1.5-angle);
    }

    plane.setAngle(angle);

可以在 http://pastebin.com/RtCB2kSZ

请记住，飞机可以在跑道点附近的任何位置

Bearing in mind the plane can be in in any position around the runway point

推荐答案

要解救的载体！

给出点A和B.创建一个从A到B的向量V(通过执行B-A).将向量V归一化为单位向量，然后将其乘以所需的距离d，最后将所得向量添加到点A.即:

Given points A and B. Create a vector V from A to B (by doing B-A). Normalize vector V into a unit vector and then just multiply it with the distance, d, you want and finally add the resulting vector to point A. ie:

  A_moved = A + |(B-A)|*d

Java(英语)

  Vector2D a_moved = a.add(b.subtract(a).norm().multiply(d));

没有角度，不需要讨厌的事情.

No angles, no nasty trig needed.

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