检测数组中最近的元素

Question

我在检测一组块中距离玩家最近的元素时遇到问题（使用圆圈）。

到目前为止我所拥有的是：

public static int closestBarrier(GameObject object, GameObject[] barriers) {
    int closest = -1;
    float minDistSq = Float.MAX_VALUE;// ridiculously large value to start
    for (int i = 0; i < barriers.length; i++) {

        float barrierRadius = barriers[i].getWidth() / 2;
        float objectRadius = object.getWidth() / 2;

        GameObject curr = barriers[i];// current
        float dx = (object.getX()) - ((curr.getX()));
        float dy = (object.getY()) - ((curr.getY()));
        float distSq = (((dx * dx + dy * dy) - objectRadius) - barrierRadius)  ;// use the squared distance
        if (distSq < minDistSq) {// find the smallest and remember the id
            minDistSq = distSq;
            closest = i;
        }
    }

    return closest;
}

它通过了大部分测试，但在最后一个测试中，最接近的返回索引是 2 而不是预期的 3。这是测试（它“最接近第四”失败：

    public final void testClosestBarrier() {
    // Closest to first
    GameObject player = new GameObject(0,1);
    player.setWidth(2);
    GameObject[] barriers = new GameObject[4];
    barriers[0] = new GameObject(8,9);
    barriers[0].setWidth(3);
    barriers[1] = new GameObject(10,15);
    barriers[1].setWidth(2);
    barriers[2] = new GameObject(15,20);
    barriers[2].setWidth(5);
    barriers[3] = new GameObject(100,210);
    barriers[3].setWidth(10);
    assertEquals("Player closest to first barrier",0,
            Submission.closestBarrier(player,barriers));

    // Closest to second
    player.setX(12);
    player.setY(12);
    assertEquals("Player closest to second barrier",1,
            Submission.closestBarrier(player,barriers));

    // Closest to third
    player.setX(12);
    player.setY(20);
    assertEquals("Player closest to third barrier",2,
            Submission.closestBarrier(player,barriers));

    // Closest to fourth
    player.setX(90);
    player.setY(100);
    assertEquals("Player closest to fourth barrier",3,
            Submission.closestBarrier(player,barriers));

}

Answer 1

您的代码是正确的，而您编写的测试是错误的 - 障碍 2 比障碍 3 更接近 90,100。

障碍 2：

(90-15)^2 + (100-20)^2

12025

障碍 3：

(100-90)^2 + (210-100)^2

12200

12025 屏障 2 更近了

编辑：在您编辑的答案中，您忘记将 objectRadius 和 barrierRadius 平方。例如

float distSq = (((dx * dx + dy * dy) - objectRadius) - barrierRadius)

在这一行中，你有 dx^2, dy^2 但只有非平方的 objectRadius 和 barrierRadius。