[DirectX][DirectInput][JoyStick]DirectInput的JoyStick创建步骤整理

DirectInput Joystick 创建指南

最新推荐文章于 2018-04-10 15:35:06 发布

原创最新推荐文章于 2018-04-10 15:35:06 发布 · 4.2k 阅读

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CC 4.0 BY-SA版权

文章标签：

#callback #null #parameters #structure #function #behavior

本文详细介绍了如何使用DirectInput创建并管理游戏控制杆（Joystick）。首先创建DirectInput对象，然后枚举Joysticks，设置Joystick数据格式，定义设备行为，获取设备访问权限，最后从Joystick检索数据。在枚举过程中，使用了回调函数EnumJoysticksCallback来创建设备，并通过SetDataFormat和SetCooperativeLevel设定设备属性。

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简介：DirectInput和其他DirectX组成部分一样，是通过硬件抽象层（HAL）和硬件仿真层（HEL）来实现，处理的输入设备一般包括鼠标、键盘、游戏控制杆、操作杆等。而且现在的DirectInput还能够支持力反馈设备。

Step 1: Creating the DirectInput Object

create a single DirectInput object as overall manager.

DirectInput8Create

// HINSTANCE g_hinst; // initialized earlier
HRESULT         hr;
LPDIRECTINPUT8 g_lpDI;

hr = DirectInput8Create(g_hinst, DIRECTINPUT_VERSION,
        IID_IDirectInput8, (void**)&g_lpDI, NULL);
if FAILED(hr)
{
    // DirectInput not available; take appropriate action
}

=================================================

Step 2: Enumerating the Joysticks

IDirectInput8::EnumDevices

//g_pDI is an initialized pointer to IDirectInput8
g_pDI->EnumDevices(DI8DEVCLASS_GAMECTRL, EnumJoysticksCallback,
NULL, DIEDFL_ATTACHEDONLY)

=================================================

Step 4: Setting the Joystick Data Format

call the IDirectInputDevice8::SetDataFormat to manipulate that device

if (FAILED(hr = g_pJoystick->SetDataFormat(&c_dfDIJoystick2)))
return hr;

typedef struct {
    LONG lX;
    LONG lY;
    LONG lZ;
    LONG lRx;
    LONG lRy;
    LONG lRz;
    LONG rglSlider[2];
    DWORD rgdwPOV[4];
    BYTE rgbButtons[128];
    LONG lVX;
    LONG lVY;
    LONG lVZ;
    LONG lVRx;
    LONG lVRy;
    LONG lVRz;
    LONG rglVSlider[2];
    LONG lAX;
    LONG lAY;
    LONG lAZ;
    LONG lARx;
    LONG lARy;
    LONG lARz;
    LONG rglASlider[2];
    LONG lFX;
    LONG lFY;
    LONG lFZ;
    LONG lFRx;
    LONG lFRy;
    LONG lFRz;
    LONG rglFSlider[2];
} DIJOYSTATE2, *LPDIJOYSTATE2;

=================================================

Step 5: Setting the Joystick Behavior

The joystick device has been created, and its data format has been set. The next step is to set its cooperative level.

if (FAILED(hr = g_pJoystick->SetCooperativeLevel(hDlg,
DISCL_EXCLUSIVE | DISCL_FOREGROUND)))
return hr;

The next step is to gather information about the capabilities of the joystick.

g_diDevCaps.dwSize = sizeof(DIDEVCAPS);//must be first initailized
if (FAILED(hr = g_pJoystick->GetCapabilities(&g_diDevCaps)))
return hr;

if (FAILED(hr = g_pJoystick->EnumObjects(EnumAxesCallback,
(VOID*)hDlg, DIDFT_AXIS)))
return hr;

=================================================

Step6: Gaining Access to the Joystick

IDirectInputDevice8::Acquire

hr = g_pJoystick->Poll();
if (FAILED(hr))
{
    hr = g_pJoystick->Acquire();
    while(hr == DIERR_INPUTLOST)
        hr = g_pJoystick->Acquire();
    return S_OK;
}

=================================================

The DI8DEVCLASS_GAMECTRL constant specifies the class of device to be enumerated.
EnumJoysticksCallback is the address of a callback function to be called each time a joystick is found.
The third parameter can be any 32-bit value that you want to make available to the callback function.
The last parameter, DIEDFL_ATTACHEDONLY, is a flag that restricts enumeration to devices that are attached to the computer.

=================================================

Step 7: Retrieving Data from the Joystick

HRESULT UpdateInputState(HWND hDlg)
{
    HRESULT     hr;
    CHAR        strText[128]; // Device state text
    DIJOYSTATE2 js;            // Direct Input joystick state
    CHAR*       str;

    if (NULL == g_pJoystick)
        return S_OK;

    // Poll the device to read the current state
    hr = g_pJoystick->Poll();
    if (FAILED(hr))
    {
        // Attempt to reacquire joystick
    }
    hr = g_pJoystick->GetDeviceState(sizeof(DIJOYSTATE2), &js);
    if (FAILED(hr))
        return hr;

DIJOYSTATE2. This structure holds data for up to six axes, 128 buttons, and four point-of-view hats.
Joystick buttons work just like keys or mouse buttons. If the high bit of the returned byte is 1, the button is pressed.
返回字节最高位为1，则按键处于按下状态

Step 3: Creating the DirectInput Joystick Device

IDirectInput8::EnumDevices枚举到设备后调用EnumJoysticksCallback回调函数，在回调函数中调用IDirectInput8::CreateDevice建立设备。

IDirectInput8::CreateDevice有三个参数：

1.枚举设备GUID（由DIDEVICEINSTANCE结构体提供，枚举到设备后DIDEVICEINSTANCE结构体通过指针传递给回调函数）

The EnumJoysticksCallback callback function parameters are as follows:

A pointer to the device instance, supplied by the DirectInput system when the device is enumerated.
A pointer to a 32-bit value that you supplied as a parameter to IDirectInput8::EnumDevices

(NULL = VOID* pContext)

BOOL CALLBACK EnumJoysticksCallback(const DIDEVICEINSTANCE*
                                       pdidInstance, VOID* pContext)
{
    HRESULT hr;

    // Obtain an interface to the enumerated joystick.
    hr = g_pDI->CreateDevice(pdidInstance->guidInstance,
                                &g_pJoystick, NULL);
    if(FAILED(hr))
        return DIENUM_CONTINUE;

    return DIENUM_STOP;