XNA - 如何判断拇指棒是否被“抽动”在某个方向

Question

API（3 或 4）中是否有任何内容可以告诉我操纵杆是否朝一个方向移动，就像在菜单中相当于按 DPad 上的某个方向一样？ Buttons 枚举中似乎有一些 Thumbstick* 成员，但我找不到关于它们的合适文档。

只是想在我自己动手之前确保我没有遗漏一些明显的东西。谢谢！

Answer 1

没有 XNA 方法可以告诉您拇指操纵杆是否在该帧中“抽动”。

最简单的方法是存储旧的操纵杆状态。如果状态原本为零且现在非零，则它已被抽搐。

加法：

而不是检查状态是否为零且现在是否非零。您可以使用问题中提到的枚举中的拇指操纵杆按钮来确定操纵杆是否已“抽动”。在这种情况下，您将操纵杆视为 DPad，并且必须独立测试每个方向。下面的代码展示了这个方法：

private void ProcessUserInput()
{
    GamePadState gamePadState = GamePad.GetState(PlayerIndex.One);

    if (m_lastGamePadState.IsButtonUp(Buttons.LeftThumbstickUp) && gamePadState.IsButtonDown(Buttons.LeftThumbstickUp))
    {
        PrevMenuItem();
    }

    if (m_lastGamePadState.IsButtonUp(Buttons.LeftThumbstickDown) && gamePadState.IsButtonDown(Buttons.LeftThumbstickDown))
    {
        NextMenuItem();
    }

    m_lastGamePadState = gamePadState;
}

Answer 2

Xbox 360 控制器上的摇杆可以像按钮一样“推入”，映射到 GamePadButtons.LeftStick 和 GamePadButtons.RightStick。这些显然不是您想要的。

以下是我用于检测任何方向上的“按下”的代码（其中padLeftPushActive存储在帧之间）：

Vector2 padLeftVector = gamePadState.ThumbSticks.Left;
bool lastPadLeftPushActive = padLeftPushActive;
if(padLeftVector.Length() > 0.85f)
    padLeftPushActive = true;
else if(padLeftVector.Length() < 0.75f)
    padLeftPushActive = false;

if(!lastPadLeftPushActive && padLeftPushActive)
{
    DoSomething(Vector2.Normalize(padLeftVector));
}

修改此代码以使其检测应该相当简单只需按菜单所需的特定方向即可。

Answer 3

是 GamePadState.Thumbsticks您在寻找什么财产？

Answer 4

这是我想出的解决方案，以防它对任何人有用：

    enum Stick {
        Left,
        Right,
    }
    GamePadState oldState;
    GamePadState newState;

    /// <summary>
    /// Checks if a thumbstick was quickly tapped in a certain direction. 
    /// This is useful for navigating menus and other situations where
    /// we treat a thumbstick as a D-Pad.
    /// </summary>
    /// <param name="which">Which stick to check: left or right</param>
    /// <param name="direction">A vector in the direction to check. 
    /// The length, which should be between 0.0 and 1.0, determines 
    /// the threshold.</param>
    /// <returns>True if a twitch was detected</returns>
    public bool WasStickTwitched(Stick which, Vector2 direction)
    {
        if (direction.X == 0 && direction.Y == 0)
            return false;

        Vector2 sold, snew;
        if (which == Stick.Left)
        {
            sold = oldState.ThumbSticks.Left;
            snew = newState.ThumbSticks.Left;
        }
        else
        {
            sold = oldState.ThumbSticks.Right;
            snew = newState.ThumbSticks.Right;
        }

        Vector2 twitch = snew;
        bool x = (direction.X == 0 || twitch.X / direction.X > 1);
        bool y = (direction.Y == 0 || twitch.Y / direction.Y > 1);
        bool tnew = x && y;

        twitch = sold;
        x      = (direction.X == 0 || twitch.X / direction.X > 1);
        y      = (direction.Y == 0 || twitch.Y / direction.Y > 1);
        bool told = x && y;

        return tnew && !told;
    }