Two-Kings - DirectInput Tutorial 3: Using The Mouse

cinput.h

At the beginning of this file we have some constants, which define the eight supported mouse buttons. The following vertex format and the structure are used to display the cursor. I will not explain this code here, because it's enough to fill a new tutorial and it is more Direct3D than DirectInput.

//constants for mouse buttons (NEW)
#define DIMOUSE_LEFTBUTTON   0
#define DIMOUSE_RIGHTBUTTON  1
#define DIMOUSE_MIDDLEBUTTON 2
#define DIMOUSE_4BUTTON      3
#define DIMOUSE_5BUTTON      4
#define DIMOUSE_6BUTTON      5
#define DIMOUSE_7BUTTON      6
#define DIMOUSE_8BUTTON      7

//vertex format for cursor (NEW)
#define D3DFVF_CURSORVERTEX (D3DFVF_XYZRHW | D3DFVF_DIFFUSE | D3DFVF_TEX1)

struct D3DCURSORVERTEX
{
float fX,
      fY,
      fZ,
      fRHW;
DWORD dwColor;
float fU,
      fV;
};

Here we come to our DirectInput class. The most things are clear. The important new things are the function to init the mouse, the second device for the mouse and the DIMOUSESTATE2 structure, which holds the information of the current mouse state.

class CInput
{
public:
                         CInput(DWORD,DWORD);
                         ~CInput(void);
    bool                 InitDirectInput(void); //init DirectInput
    bool                 InitKeyboard(void);    //init keyboard
    bool                 InitMouse(void);       //init mouse (NEW)
    bool                 Update(void);          //update device state

    bool                 KeyPressed(int);       //check for key

    //draws mouse cursor (NEW)
    void                 DrawCursor(void);
    //set new cursor (NEW)
    void                 SetCursor(const char*,int,int,DWORD);
    //set cursor attributes (NEW)
    void                 SetAttributes(bool,float);
    //set new cursor position (NEW)
    void                 SetCursorPosition(float,float);

    //get relative movement (NEW)
    float                GetRelativeX(void);
    float                GetRelativeY(void);
    //get wheel movement (NEW)
    float                GetRelativeZ(void);
    //get cursor position (NEW)
    float                GetAbsoluteX(void);
    float                GetAbsoluteY(void);
    //check for mouse button (NEW)
    bool                 MouseButtonDown(int);

private:
    LPDIRECTINPUT8       m_pDIObject;           //DirectInput object
    LPDIRECTINPUTDEVICE8 m_pDIKeyboardDevice;   //keyboard device
    LPDIRECTINPUTDEVICE8 m_pDIMouseDevice;      //mouse device (NEW)

    char                 m_KeyBuffer[256];      //buffer for keys

    LPDIRECT3DTEXTURE9   m_pCursorTexture;      //cursor texture (NEW)
    //mouse state structure (NEW)
    DIMOUSESTATE2        m_MouseState;
    bool                 m_bInverted;           //inverted y axis (NEW)
    float                m_fSensitivity,        //mouse sensitivity (NEW)
                         m_fCursorX,            //cursor position (NEW)
                         m_fCursorY;
    int                  m_iHotSpotX,           //cursor hot spot (NEW)
                         m_iHotSpotY;
    DWORD                m_dwAxes,              //number of axes (NEW)
                         m_dwButtons,           //number of buttons (NEW)
                         m_dwCursorColor,       //cursor color (NEW)
                         m_dwScreenWidth,       //screen width (NEW)
                         m_dwScreenHeight;      //screen height (NEW)
};

cinput.cpp

Now we can start with the functions. First we have to add InitMouse() to the constructor. When you create the object you have to pass the screen dimensions to it. They are needed for the cursor.

if(!InitDirectInput()) g_App.SetD3DStatus(false);
else if(!InitKeyboard() || !InitMouse()) g_App.SetD3DStatus(false);

And, of course, we also have to clean-up at the end. That's why we also have to change the destructor.

if(m_pDIMouseDevice != NULL)
 {
 m_pDIMouseDevice->Unacquire();
 m_pDIMouseDevice->Release();
 m_pDIMouseDevice = NULL;
 }

Now comes the most important stuff. Before we can use the mouse we have to init it, of course. This is done like with the keyboard. At the beginning we declare a structure, which we will use later. Then we create the device with the help of the DirectInput object.

bool CInput::InitMouse(void)
{
DIDEVCAPS MouseCapabilities; //device capabilities

if(FAILED(m_pDIObject->CreateDevice(GUID_SysMouse,
                                    &m_pDIMouseDevice,
                                    NULL)))
 {
 MessageBox(g_App.GetWindowHandle(),
            "CreateDevice() failed!",
            "InitMouse()",
            MB_OK);
 return false;
 }

The next thing is to set the data format. We set it to c_dfDIMouse2, which declares that we want to use the system mouse with up to eight buttons.

if(FAILED(m_pDIMouseDevice->SetDataFormat(&c_dfDIMouse2)))
 {
 MessageBox(g_App.GetWindowHandle(),
            "SetDataFormat() failed!",
            "InitMouse()",
            MB_OK);
 return false;
 }

Now we have to set the cooperative level. We set it to DISCL_BACKGROUND and DISCL_NONEXCLUSIVE. For more information on this take a look in the DirectX SDK documentation.

if(FAILED(m_pDIMouseDevice->SetCooperativeLevel(g_App.GetWindowHandle(),
                                                DISCL_BACKGROUND | 
                                                DISCL_NONEXCLUSIVE)))
 {
 MessageBox(g_App.GetWindowHandle(),
            "SetCooperativeLevel() failed!",
            "InitMouse()",
            MB_OK);
 return false;
 }

Before we can get data from the mouse we have to acquire it.

if(FAILED(m_pDIMouseDevice->Acquire()))
 {
 MessageBox(g_App.GetWindowHandle(),
            "Acquire() failed!",
            "InitMouse()",
            MB_OK);
 return false;
 }

At the end we use the structure from the beginning. The next part of code fills the structure with the device capabilities and checks if the mouse is connected with the computer. So we can also find out if we have a mouse wheel or how many buttons the mouse has.

MouseCapabilities.dwSize = sizeof(MouseCapabilities);
m_pDIMouseDevice->GetCapabilities(&MouseCapabilities);

if(!(MouseCapabilities.dwFlags & DIDC_ATTACHED))
 {
 MessageBox(g_App.GetWindowHandle(),
            "Mouse is currently not attached!",
            "InitMouse()",
            MB_OK);
 return false;
 }

m_dwAxes = MouseCapabilities.dwAxes;
m_dwButtons = MouseCapabilities.dwButtons;

SetCursor("arrow.bmp",0,0,0xffffffff);
SetAttributes(false,1.0f);

return true;
} //InitMouse

Now we want to get data from the mouse. We only have to add a small part of code to the Update() function, which updates the current device states. We fill the DIMOUSESTATE2 structure with the mouse state. If the function returns DIERR_INPUTLOST we acquire the device again, because it has been lost.

if(DIERR_INPUTLOST == m_pDIMouseDevice->GetDeviceState(sizeof(m_MouseState),
		                                       (LPVOID)&m_MouseState))
 {
 m_pDIMouseDevice->Acquire();
 }

The last function I will explain is MouseButtonDown(). The parameter is the mouse button, which we want to check. You can use the constants from the beginning to check the buttons. If the high-order bit of the array is set the button is down and we return true.

bool CInput::MouseButtonDown(int Button)
{
if(m_MouseState.rgbButtons[Button] & 0x80)
 {
 return true;
 }

return false;
} //MouseButtonDown

That's all I will explain, because I think you can find out the rest by yourself. If you have questions to the not explained code let me know.

DirectX Tutorials

Game Tutorials

Miscellaneous

DirectInput

Related Material

Tutorial 3: Using The Mouse

Content

cinput.h

cinput.cpp