java - 如何使物体转向相反的方向？

Question

考虑出界位置为 6 和 -6。

我想让船掉头朝相反的方向移动。

这是我的代码..它仍然没有100%按照我想要的方式工作。我很好奇看看有没有人 有任何想法如何改进。 这是我的代码的逻辑。

//If the ship hits a boundary it turns around and moves in the opp.
//direction. To do this, the ship's velocty should be flipped from a 
//negative into a positive number, or from pos to neg if boundary
//is hit.

//if ship position is -5 at velocity -1 new ship pos is -6
//if ship position is -6 at velocity -1 new ship velocity is +1
//                                      new ship position is +5

这是我的代码:

public void move() 
{
    position = velocity + position;

    if (position > 5)
    {
        velocity = -velocity;
    }
    else if (position < -5)
    {
        velocity = +velocity;
    }
}

Answer 1

代码velocity = +velocity;不会将负速度更改为正速度。这相当于将速度乘以 +1，但不会改变符号。

要在出界时翻转速度符号，您需要始终乘以-1。

不太清楚界限是什么，所以下面我假设它们是 6 和 -6。

position += velocity;
//make sure the ship cannot go further than the bounds
//but also make sure that the ship doesn't stand still with large velocities
if (position > 6)
{
    velocity = -velocity;
    position = 6;
}
if (position < -6)
{
    velocity = -velocity;
    position = -6;
}