C++ Directx mouse input acting weird after focus lost

Question

Hello I've a small problem with my mouse input after I lose window focus (alt+tab / windows key).

After the focus is back to the game window, the mouse (yaw) is acting slow and not responsive (the pitch is working fine for some reason). Sometimes it moves and sometimes it doesn't move at all.

Here is some of the code:

bool Game::initDirectInput(HINSTANCE hInstance)
{
    hr = DirectInput8Create(hInstance, DIRECTINPUT_VERSION, IID_IDirectInput8, (void**)&directInput, NULL); 

    hr = directInput->CreateDevice(GUID_SysKeyboard, &DIKeyboard, NULL);

    hr = directInput->CreateDevice(GUID_SysMouse, &DIMouse, NULL);

    hr = DIKeyboard->SetDataFormat(&c_dfDIKeyboard);
    hr = DIKeyboard->SetCooperativeLevel(hWnd, DISCL_FOREGROUND | DISCL_NONEXCLUSIVE);

    hr = DIMouse->SetDataFormat(&c_dfDIMouse2);
    hr = DIMouse->SetCooperativeLevel(hWnd, DISCL_FOREGROUND | DISCL_EXCLUSIVE | DISCL_NOWINKEY);

    return true;
}

void Game::detectInput(double delta)
{
    DIMOUSESTATE2 mouseCurrState;

    BYTE keyboardState[256];

    DIKeyboard->Acquire();
    DIMouse->Acquire();

    DIMouse->GetDeviceState(sizeof(DIMOUSESTATE2), &mouseCurrState);

    DIKeyboard->GetDeviceState(sizeof(keyboardState),(LPVOID)&keyboardState);

    camera.detectInput(delta, &keyboardState[0], &mouseCurrState);
}

void Camera::detectInput(double delta, BYTE *keyboardState, DIMOUSESTATE2 *mouseCurrState){

    float speed = 16.0f * delta;


    ...


    if((mouseCurrState->lX != mouseLastState.lX) || (mouseCurrState->lY != mouseLastState.lY))
{
    camYaw += mouseCurrState->lX * 0.002f;

    camPitch += mouseCurrState->lY * 0.002f;

    if(camPitch > 0.85f)
        camPitch = 0.85f;
    if(camPitch < -0.85f)
        camPitch = -0.85f;

    mouseLastState = *mouseCurrState;
}

    update();

    return;
}

void Camera::update(){
    camRotationMatrix = XMMatrixRotationRollPitchYaw(camPitch, camYaw, 0);
    camTarget = XMVector3TransformCoord(DefaultForward, camRotationMatrix );
    camTarget = XMVector3Normalize(camTarget);

    XMMATRIX RotateYTempMatrix;
    RotateYTempMatrix = XMMatrixRotationY(camYaw);

    camRight = XMVector3TransformCoord(DefaultRight, RotateYTempMatrix);
    camForward = XMVector3TransformCoord(DefaultForward, RotateYTempMatrix);
    camUp = XMVector3Cross(camForward, camRight);

    camPosition += moveLeftRight*camRight;
    camPosition += moveBackForward*camForward;
    camPosition += moveUpDown*DefaultUp;

    moveLeftRight = 0.0f;
    moveBackForward = 0.0f;
    moveUpDown = 0.0f;

    camTarget = camPosition + camTarget;    

    camView = XMMatrixLookAtLH( camPosition, camTarget, camUp );
}

For those wondering, I've just started learning c++ and directx using this tutorial: http://www.braynzarsoft.net/index.php?p=DX11Lessons (Although I have quite some experience using OpenGL + java.)

Answer 1

I've fixed the problem by adding a simple if statement:

if(mouseLastState.lX > -10000 && mouseLastState.lX < 10000){
    camYaw += mouseLastState.lX * 0.002f;
}

The problem was that when the window got the focus back, it would return such a high value that the yaw would not be valid anymore.