C# XNA中的BoundingBox有些奇怪

我有一个奇怪的问题，边界框和东西，在使。 For循环无法正常工作，并导致变量不变的问题

for (int i = 0; i < thing.Length; i++)
        {
            for (int j = 0; j < thing.Length; j++)
            {
                if (thing[i].bb.Intersects(thing[j].bb) && i != j)
                {
                    thing[i].spriteSpeed *= -1;
                    thing[j].spriteSpeed *= -1;
                    soundEffect.Play(0.2f, -1f, 0f);
                }
            }
        }

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问题是您两次都在更新这两个对象

考虑这样一种情况，列表中有两个项，它们的边界框重叠。通过你的循环，你会得到：

i == 0, j == 0: Skip because (i == j)
i == 0, j == 1: Reverse direction of [0] and [1]
i == 1, j == 0: Reverse direction of [1] and [0]
i == 1, j == 1: Skip because (i == j)

按照顺序操作，您已将项目颠倒了两次，将其返回到原始标题

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为防止出现这种情况，并顺便减少处理完整对象列表所需的测试次数，

j

变量的起始值应始终高于

i

，因为

i Tnx Corey的所有比较都是如此。这对我来说很好。
struct Thing
    {
        public Texture2D myTexture;
        public Vector2 spritePosition;
        public Vector2 spriteSpeed;
        public BoundingBox bb;
        public Vector3 start, end;
    }

i == 0, j == 0: Skip because (i == j)
i == 0, j == 1: Reverse direction of [0] and [1]
i == 1, j == 0: Reverse direction of [1] and [0]
i == 1, j == 1: Skip because (i == j)

for (int i = 0; i < thing.Length; i++)
{
    for (int j = i + 1; j < thing.Length; j++)
    {
        if (thing[i].bb.Intersects(thing[j].bb))
        {
            thing[i].spriteSpeed *= -1;
            thing[j].spriteSpeed *= -1;
            soundEffect.Play(0.2f, -1f, 0f);
        }
    }
}