java - 获取指向其他点的下一个点

Question

我无法理解 http://en.wikipedia.org/wiki/Bresenham%27s_line_algorithm足以用 Java 编写它(我在八年级)。从起点开始，我需要到达目的地。我发现了几个论坛帖子，但没有 Java 示例。

我尝试了这个(在我的 Vector2 类中):

public Vector2 getNextPointTowardOther(Vector2 dest, int speed) {
    if (dest == null)
        return this;
    double deltaX = dest.getX() - this.x;
    double deltaY = dest.getY() - this.y;
    double direction = Math.atan(deltaY / deltaX);
    double x = this.x + (speed * Math.cos(direction));
    double y = this.y + (speed * Math.sin(direction));
    return new Vector2(x, y);
}

但它永远不会返回负的 x 或 y 坐标，而且它似乎并不完全准确。

Answer 1

为了向某个目标点移动一定的量，您必须计算从当前点到目标点的方向，并将该方向相乘与您想要使用的速度，然后将其添加到原始点:

public Vector2 getNextPointTowardOther(Vector2 dest, int speed) {
    if (dest == null)
        return this;
    double deltaX = dest.getX() - this.x;
    double deltaY = dest.getY() - this.y;

    // Compute the distance 
    double distance = Math.sqrt(deltaX*deltaX+deltaY*deltaY);

    // Compute the (normalized) direction 
    double dirX = deltaX / distance;
    double dirY = deltaY / distance;

    // (The vector (dirX, dirY) now has length 1.0)

    double x = this.x + speed * dirX;
    double y = this.y + speed * dirY;
    return new Vector2(x, y);
}