1

Interaction Devices

CIS 487/587

Bruce R. Maxim

UM-Dearborn

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User Communication

• Keyboard remains the user’s primary input device• Most GUI systems expect pointing devices as well

– Light pen – Touch screen – Mouse – Trackball – Joystick – Graphics tablet – Touch pad – Foot controls – Gloves – Eye movement detectors

3

Pointing Device Tasks

• Selection

• Positioning objects

• Orienting objects on screen

• Path tracing

• Quantify

• Text entry/editing (not easily done)

4

Comparison

• Keyboard– Fast control, require memorization and recall

• Mouse– Best choice for pointing to objects in arbitrary

positions, can be as fast as pointing with a finger

• Joystick– Poor cursor control devices, actually slower than

mouse (only use where they are game realistic)

5

Direct-Input

1. Create main DirectInput interface using CreateIDirectIntput8( )

2. (optional) Query for device GUID’s for all devices (mouse, keyboard, joystick)

3. Create each device using CreateDevice( ) please note: GUID_SysKeyboard and GUID_SysMouse are built in

4. Set cooperation level for each device using SetCooperativeLevel( )

5. Set data format for each device using SetDatFormat( )

6

Direct-Input

6. Set properties of each device using IDirectIntputDevice8::SetProperty( )

7. Acquire each device using IDirectIntputDevice8::Acquire( )

8. (optional) Poll devices using IDirectIntputDevice8::Poll( )

9. Read device using IDirectIntputDevice8::GetStateDevice( )

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Input

• DirectX can request input in two ways– Immediate input (default)– Buffered input

• LaMothe only uses immediate input• DirectX can cut Windows out of the

message loop altogether, so be careful when you set each device cooperation level

8

LaMothe Example

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Keyboard Global Declarations

#include <ddraw.h> // directX includes

#include <dinput.h>

#include "T3DLIB1.H"

// directinput globals

LPDIRECTINPUT8 lpdi = NULL; // dinput object

LPDIRECTINPUTDEVICE8 lpdikey = NULL; // dinput keyboard

LPDIRECTINPUTDEVICE8 lpdimouse = NULL; // dinput mouse

LPDIRECTINPUTDEVICE8 lpdijoy = NULL; // dinput joystick

GUID joystickGUID; // guid for main joystick

char joyname[80]; // name of joystick

 

// these contain the target records for all di input packets

UCHAR keyboard_state[256]; // contains keyboard state table

DIMOUSESTATE mouse_state; // contains state of mouse

DIJOYSTATE joy_state; // contains state of joystick

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Game_Init( )// initialize directdrawDDraw_Init(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP);// first create the direct input objectif (DirectInput8Create(main_instance,DIRECTINPUT_VERSION, IID_IDirectInput8, (void **)&lpdi,NULL)!=DI_OK) return(0);// create a keyboard device //////////////////////////////////if (lpdi->CreateDevice(GUID_SysKeyboard, &lpdikey, NULL)!=DI_OK)

return(0);// set cooperation levelif (lpdikey->SetCooperativeLevel(main_window_handle, DISCL_NONEXCLUSIVE | DISCL_BACKGROUND)!=DI_OK) return(0);// set data formatif (lpdikey->SetDataFormat(&c_dfDIKeyboard)!=DI_OK) return(0);// acquire the keyboardif (lpdikey->Acquire()!=DI_OK) return(0);

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Game_Shutdown( )

// kill the reactor

Destroy_Bitmap(&reactor);

 

// kill skelaton

Destroy_BOB(&skelaton);

 

// release keyboard

lpdikey->Unacquire();

lpdikey->Release();

lpdi->Release();

 

// shutdonw directdraw

DDraw_Shutdown();

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Game_Main( )// get player input// get the keyboard datalpdikey->GetDeviceState(256, (LPVOID)keyboard_state);// reset motion flagplayer_moving = 0;// test direction of motionif (keyboard_state[DIK_RIGHT] && keyboard_state[DIK_UP]) { // move skelaton skelaton.x += 2; skelaton.y -= 2; dx=2; dy =- 2; // set motion flag player_moving = 1; // check animation needs to change if (skelaton.curr_animation != SKELATON_NEAST) Set_Animation_BOB(&skelaton,SKELATON_NEAST);} // end if …

13

Mouse

• Detects changes in X, y position (Mickeys)• Specifies “absolute” position• Can specify velcoity range• Good for selecting objects, moving objects, or

changing head position (view)• Hard to center if used as joystick replacement• Has small number of buttons (2 or 3

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LaMothe Example

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Mouse Global Declarations#define BUTTON_SPRAY 0 // defines for each button#define BUTTON_PENCIL 1#define BUTTON_ERASE 2#define BUTTON_EXIT 3

// directinput globalsLPDIRECTINPUT8 lpdi = NULL; // dinput objectLPDIRECTINPUTDEVICE8 lpdikey = NULL; // dinput keyboardLPDIRECTINPUTDEVICE8 lpdimouse = NULL; // dinput mouseLPDIRECTINPUTDEVICE8 lpdijoy = NULL; // dinput joystick GUID joystickGUID; // guid for main joystickchar joyname[80]; // name of joystick // these contain the target records for all di input packetsUCHAR keyboard_state[256]; // contains keyboard state tableDIMOUSESTATE mouse_state; // contains state of mouseDIJOYSTATE joy_state; // contains state of joystick

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Game_Init( )

// first create the direct input object

DirectInput8Create(main_instance,DIRECTINPUT_VERSION,IID_IDirectInput8, (void **)&lpdi,NULL);

 

// create a mouse device /////////////////////////////////////

lpdi->CreateDevice(GUID_SysMouse, &lpdimouse, NULL);

 

// set cooperation level

lpdimouse->SetCooperativeLevel(main_window_handle, DISCL_NONEXCLUSIVE | DISCL_BACKGROUND);

 

// set data format

lpdimouse->SetDataFormat(&c_dfDIMouse);

 

// acquire the mouse

lpdimouse->Acquire();

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Game_Init( )// set the global mouse positionmouse_x = screen_height/2;mouse_y = screen_height/2; // load the master bitmap in with all the graphicsLoad_Bitmap_File(&bitmap8bit, "PAINT.BMP");Set_Palette(bitmap8bit.palette); // make sure all the surfaces are clean before startingDDraw_Fill_Surface(lpddsback, 0);DDraw_Fill_Surface(lpddsprimary, 0); // create the pointer bobCreate_BOB(&pointer,mouse_x,mouse_y,32,34,1, BOB_ATTR_VISIBLE |

BOB_ATTR_SINGLE_FRAME,DDSCAPS_SYSTEMMEMORY);  // load the image for the pointer inLoad_Frame_BOB(&pointer,&bitmap8bit,0,0,2,BITMAP_EXTRACT_MODE_CELL);

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Game_Init( )

// set clipping rectangle to screen extents so mouse cursor

// doens't mess up at edges

RECT screen_rect = {0,0,screen_width,screen_height};

lpddclipper = DDraw_Attach_Clipper(lpddsback,1,&screen_rect);

 

// hide the mouse

ShowCursor(FALSE);

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Game_Shutdown( )

// first unacquire the mouse

lpdimouse->Unacquire();

 

// now release the mouse

lpdimouse->Release();

 

// release directinput

lpdi->Release();

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Game_Main( )// move the mouse cursormouse_x+=(mouse_state.lX);mouse_y+=(mouse_state.lY); // test bounds // first x boundariesif (mouse_x >= screen_width) mouse_x = screen_width-1;elseif (mouse_x < 0) mouse_x = 0; // now the y boundariesif (mouse_y >= screen_height) mouse_y= screen_height-1;elseif (mouse_y < 0) mouse_y = 0;

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Game_Main( )

// position the pointer bob to the mouse coords

pointer.x = mouse_x - 16;

pointer.y = mouse_y - 16;

// test what the user is doing with the mouse

if ((mouse_x > 3) && (mouse_x < 500-3) &&

(mouse_y > 3) && (mouse_y < SCREEN_HEIGHT-3))

{

// mouse is within canvas region

// if left button is down then draw

if (mouse_state.rgbButtons[0])

{

…

};

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Game Pads

• Simplified keyboard• Buttons have good stimulus/response

compatibility• Lets you use two hand• Good for multiplayer games• Can require weird combinations of buttons• Don’t get to rely on fastest finger (index)• Doesn’t support variable input

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Joysticks

• Lots of devices look like joysticks(digital – 8 positions, analog x,y deflection)

• Allow variable input plus buttons• Great for specifying changes• Can be used to specify “rate in a direction”• Not good for specifying absolute positions

(need to “hold position steady)• Not good for many arcade games

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Using Joysticks & Game Pads

1. Scan for all devices and record GUID’s

2. Create joystick device using one GUID

3. Use interface from step 2 and create another interface (release the first)

4. Set cooperation level

5. Set data format and properties

6. Acquire joystick

7. Read joystick using Poll and GetDevice

25

LaMothe Example

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Joystick Global Declarations

// directinput globals

LPDIRECTINPUT8 lpdi = NULL; // dinput object

LPDIRECTINPUTDEVICE8 lpdikey = NULL; // dinput keyboard

LPDIRECTINPUTDEVICE8 lpdimouse = NULL; // dinput mouse

LPDIRECTINPUTDEVICE8 lpdijoy = NULL; // dinput joystick

GUID joystickGUID; // guid for main joystick

char joyname[80]; // name of joystick

 

// these contain the target records for all di input packets

UCHAR keyboard_state[256]; // contains keyboard state table

DIMOUSESTATE mouse_state; // contains state of mouse

DIJOYSTATE joy_state; // contains state of joystick

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DI_Enum_Joysticks( )

// this function enumerates the joysticks, but

// stops at the first one and returns the

// instance guid of it, so we can create it

 

*(GUID*)guid_ptr = lpddi->guidInstance;

 

// copy name into global

strcpy(joyname, (char *)lpddi->tszProductName);

 

// stop enumeration after one iteration

return(DIENUM_STOP);

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Game_Init( )// joystick creation section ////////////////////////////////

// first create the direct input objectif (DirectInput8Create(main_instance,DIRECTINPUT_VERSION,

IID_IDirectInput8, (void **)&lpdi,NULL)!=DI_OK) return(0);

// first find the f***ing GUID of your particular joysticklpdi->EnumDevices(DI8DEVCLASS_GAMECTRL, DI_Enum_Joysticks, &joystickGUID, DIEDFL_ATTACHEDONLY);  if (lpdi->CreateDevice(joystickGUID, &lpdijoy, NULL)!=DI_OK) return(0); // set cooperation levelif (lpdijoy->SetCooperativeLevel(main_window_handle,

DISCL_NONEXCLUSIVE | DISCL_BACKGROUND)!=DI_OK) return(0);

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Game_Init( )// set data formatif (lpdijoy->SetDataFormat(&c_dfDIJoystick)!=DI_OK) return(0); // set the range of the joystickDIPROPRANGE joy_axis_range; // first x axisjoy_axis_range.lMin = -24;joy_axis_range.lMax = 24;

joy_axis_range.diph.dwSize = sizeof(DIPROPRANGE); joy_axis_range.diph.dwHeaderSize = sizeof(DIPROPHEADER); joy_axis_range.diph.dwObj = DIJOFS_X;joy_axis_range.diph.dwHow = DIPH_BYOFFSET;

lpdijoy->SetProperty(DIPROP_RANGE,&joy_axis_range.diph);

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Game_Init( )// now y-axisjoy_axis_range.lMin = -24;joy_axis_range.lMax = 24;joy_axis_range.diph.dwSize = sizeof(DIPROPRANGE); joy_axis_range.diph.dwHeaderSize = sizeof(DIPROPHEADER); joy_axis_range.diph.dwObj = DIJOFS_Y;joy_axis_range.diph.dwHow = DIPH_BYOFFSET; lpdijoy->SetProperty(DIPROP_RANGE,&joy_axis_range.diph); // and now the dead band (zone where movements are ignored)DIPROPDWORD dead_band; // here's our property word dead_band.diph.dwSize = sizeof(dead_band);dead_band.diph.dwHeaderSize = sizeof(dead_band.diph);dead_band.diph.dwObj = DIJOFS_X;dead_band.diph.dwHow = DIPH_BYOFFSET;

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Game_Init( )// 10% will be used on both sides of the range +/-dead_band.dwData = 1000; // finally set the propertylpdijoy->SetProperty(DIPROP_DEADZONE,&dead_band.diph); dead_band.diph.dwSize = sizeof(dead_band);dead_band.diph.dwHeaderSize = sizeof(dead_band.diph);dead_band.diph.dwObj = DIJOFS_Y;dead_band.diph.dwHow = DIPH_BYOFFSET;// 10% will be used on both sides of the range +/-dead_band.dwData = 1000; // finally set the propertylpdijoy->SetProperty(DIPROP_DEADZONE,&dead_band.diph);// acquire the joystickif (lpdijoy->Acquire()!=DI_OK) return(0);

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Game_Shutdown( )

// release joystick

lpdijoy->Unacquire();

lpdijoy->Release();

lpdi->Release();

 

// shutdonw directdraw

DDraw_Shutdown();

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Game_Main( )// get joystick datalpdijoy->Poll(); // this is needed for joysticks onlylpdijoy->GetDeviceState(sizeof(DIJOYSTATE), (LPVOID)&joy_state); // lock the back bufferDDraw_Lock_Back_Surface(); // draw the background reactor imageDraw_Bitmap(&playfield, back_buffer, back_lpitch, 0); // unlock the back bufferDDraw_Unlock_Back_Surface(); // is the player moving?blaster.x+=joy_state.lX;blaster.y+=joy_state.lY;

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Game_Main( )

// is player firing?

if (joy_state.rgbButtons[0])

Start_Missile();

 

// display joystick and buttons 0-7

sprintf(buffer,"Joystick Stats: X-Axis=%d, Y-Axis=%d, buttons(%d,%d,%d,%d,%d,%d,%d,%d)", joy_state.lX,joy_state.lY,

joy_state.rgbButtons[0], joy_state.rgbButtons[1], joy_state.rgbButtons[2], joy_state.rgbButtons[3],

joy_state.rgbButtons[4], joy_state.rgbButtons[5],

joy_state.rgbButtons[6], joy_state.rgbButtons[7]);

// print out name of joystick

sprintf(buffer, "Joystick Name & Vendor: %s",joyname);

Draw_Text_GDI(buffer,0,SCREEN_HEIGHT-40,RGB(255,255,50),lpddsback);

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Force Feedback

• Gameplay can influence input device by producing some resistive force

• Requires bi-directional communication between interaction device and computer(e.g. joysticks, steering wheels, yokes, etc.)

• Examples– Engine-hum (sine-wave)– Machine gun (square-wave vibrations)

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Force Feedback

• Lags > 25ms between visual event and feedback are noticable

• Designers need to anticipate effects of conditions (e.g. wind) and surface texture (e.g. bumps and grit) in planning game play

• Can be mesmerizing to players (adds to realism)

• LaMothe has example, can’t run on my laptop (my FFB device is not USB)