Introduction and design philosophy

The MinVR event system is based on the Event class (Event.H). To make things easier, there are no subclasses of Event. Instead, individual events are distinguished based on their name string. This makes it easier to add new event types in the future and adjust event names in static config files. Additionally, basing event types on strings makes it very easy to make a keyboard event look like a tracker event which can be a useful technique for debugging your VR app.

However, because events are not subclassed, different events will contain different valid member variables. For example, only keyboard and mouse events will have a valid window parameter, because other event types are not associated with a specific window. To check which members are valid, just print the event using the toString() method.

Handling events in your application

Before drawing each frame of your application, the MinVR engine will query the input devices and application windows to poll them for input. Events are added to an array that is passed to the doUserInputAndPreDrawComputation(const std::vector<EventRef> &events, double synchronizedTime) method in your application. Note, that the events in the events array are sorted by increasing time and may contain duplicate events. For instance, if your framerate is slow, you may have multiple mouse move events in the array, etc.

For example, here is how you might handle head position updates or a keyboard event:

void MyApp::doUserInputAndPreDrawComputation(const std::vector<EventRef> &events, double synchronizedTime)
{
        for(int i=0; i < events.size(); i++) {
                string name = events[i]->getName();
                if (name == "Head_Tracker")
                {
                        glm::mat4 headPosition = events[i]->getCoordinateFrameData();
        }
                else if (name == "kbd_A_down")
                { 
                        cout << "Pressed the A key at " << events[i]->getTimestamp() << ". The key value is " << events[i]->getMsgData() << endl;
                }
        }
}

Event Types

The following sections describe the individual event types.

VRPN events

VRPN tracker device events contain a glm::mat4 representing the trackers rotation and translation from the room space origin. The name of the event is based on the <name>_EventsToGenerate string in the input devices config file.

VRPN button events are named after the <name>_EventsToGenerate with a suffix of _up or _down depending on whether the button was pressed or released. They also contain an id value corresponding with the order in the <name>_EventsToGenerate string. For example, if multiple vrpn buttons are available, the string might look like:

    vrpndevice_EventsToGenerate wand_btn_0 wand_btn_1 wand_btn_2

In this case, the button id would match the suffix of the button name.

Similarly, VRPN analog events also contain a id related to the position of the event name in the <name>_EventsToGenerate string. Analog events also contain a 1D analog data value.

TUIO multi-touch events

TUIO events contain the following names and data values.

Name	Data	Notes
`TUIO_Cursor<id num>_up`	id integer
`TUIO_Cursor<id num>_down`	id integer, (x, y) position
`TUIO_CursorMove<id num> <td> id integer, (x, y, velocity, acceleration) <td> <tr><td>`TUIO_Obj<id num>	id integer, (x, y, angle)

3DConnexion SpaceNavigator events

Name	Data	Notes
`SpaceNav_Trans`	(x, y, z)
`SpaceNav_Rot`	(x angle, y angle, z angle)	Euler Angles XYZ order

Mouse Events

Mouse event names and their valid data values are found in the table below.

Name	Data	Notes
`mouse_btn_left_down`	window reference
`mouse_btn_left_up`	window reference
`mouse_btn_right_down`	window reference
`mouse_btn_right_up`	window reference
`mouse_btn_middle_down`	window reference
`mouse_btn_middle_down`	window reference
`mouse_pointer`	window reference, (x, y) position	Position is relative to the upper left corner of the client area of the window
`mouse_pointer_entered`	window reference	When the cursor enters the client area of the window
`mouse_pointer_left`	window reference	When the cursor leaves the client area of the window
`mouse_scroll`	window reference, (x, y) offsets	Scroll offsets along the x and y axes

Keyboard Events

In MinVR, the names of keyboard events start with the prefix kbd_. Each event contains a reference to the focused window, and if it make sense, a string value for the key. Each keyboard event ends with an action suffix, either down, up, or repeat. For example when the A key is pressed, the event name would be kbd_A_down.

It is also possible to have modifiers, for example to hold shift and press the A key. In this case, the possible modifier names are SHIFT, ALT, CTRL, and SUPER. These are added to the name string before the action. So, for the example above, the name would be kbd_A_SHIFT_down. For the shift keys with letters, the string value is automatically modified. The string for the previous event would be "A" rather than the usual "a". It is possible to have multiple modifiers. For example, kbd_A_SHIFTCTRL_down is valid.

Name	Data	Notes
`kbd_A_<action>`	window reference, string=`"a"`
`kbd_B_<action>`	window reference, string=`"b"`
`kbd_C_<action>`	window reference, string=`"c"`
`kbd_D_<action>`	window reference, string=`"d"`
`kbd_E_<action>`	window reference, string=`"e"`
`kbd_F_<action>`	window reference, string=`"f"`
`kbd_G_<action>`	window reference, string=`"g"`
`kbd_H_<action>`	window reference, string=`"h"`
`kbd_I_<action>`	window reference, string=`"i"`
`kbd_J_<action>`	window reference, string=`"j"`
`kbd_K_<action>`	window reference, string=`"k"`
`kbd_L_<action>`	window reference, string=`"l"`
`kbd_M_<action>`	window reference, string=`"m"`
`kbd_N_<action>`	window reference, string=`"n"`
`kbd_O_<action>`	window reference, string=`"o"`
`kbd_P_<action>`	window reference, string=`"p"`
`kbd_Q_<action>`	window reference, string=`"q"`
`kbd_R_<action>`	window reference, string=`"r"`
`kbd_S_<action>`	window reference, string=`"s"`
`kbd_T_<action>`	window reference, string=`"t"`
`kbd_U_<action>`	window reference, string=`"u"`
`kbd_V_<action>`	window reference, string=`"v"`
`kbd_W_<action>`	window reference, string=`"w"`
`kbd_X_<action>`	window reference, string=`"x"`
`kbd_Y_<action>`	window reference, string=`"y"`
`kbd_Z_<action>`	window reference, string=`"z"`
`kbd_0_<action>`	window reference, string=`"0"`
`kbd_1_<action>`	window reference, string=`"1"`
`kbd_2_<action>`	window reference, string=`"2"`
`kbd_3_<action>`	window reference, string=`"3"`
`kbd_4_<action>`	window reference, string=`"4"`
`kbd_5_<action>`	window reference, string=`"5"`
`kbd_6_<action>`	window reference, string=`"6"`
`kbd_7_<action>`	window reference, string=`"7"`
`kbd_8_<action>`	window reference, string=`"8"`
`kbd_9_<action>`	window reference, string=`"9"`
`kbd_SPACE_<action>`	window reference, string=`" "`
`kbd_MINUS_<action>`	window reference, string=`"-"`
`kbd_EQUAL_<action>`	window reference, string=`"="`
`kbd_LEFT_BRACKET_<action>`	window reference, string=`"["`
`kbd_RIGHT_BRACKET_<action>`	window reference, string=`"]"`
`kbd_BACKSLASH_<action>`	window reference, string="\"
`kbd_SEMICOLON_<action>`	window reference, string=`";"`
`kbd_APOSTROPHE_<action>`	window reference, string=`'`
`kbd_GRAVE_ACCENT_<action>`	window reference, string="`"
`kbd_COMMA_<action>`	window reference, string=`","`
`kbd_PERIOD_<action>`	window reference, string=`"."`
`kbd_SLASH_<action>`	window reference, string=`"/"`
`kbd_WORLD1_<action>`	window reference
`kbd_WORLD2_<action>`	window reference
`kbd_ESC_<action>`	window reference
`kbd_F1_<action>`	window reference
`kbd_F2_<action>`	window reference
`kbd_F3_<action>`	window reference
`kbd_F4_<action>`	window reference
`kbd_F5_<action>`	window reference
`kbd_F6_<action>`	window reference
`kbd_F7_<action>`	window reference
`kbd_F8_<action>`	window reference
`kbd_F9_<action>`	window reference
`kbd_F10_<action>`	window reference
`kbd_F11_<action>`	window reference
`kbd_F12_<action>`	window reference
`kbd_F13_<action>`	window reference
`kbd_F14_<action>`	window reference
`kbd_F15_<action>`	window reference
`kbd_F16_<action>`	window reference
`kbd_F17_<action>`	window reference
`kbd_F18_<action>`	window reference
`kbd_F19_<action>`	window reference
`kbd_F20_<action>`	window reference
`kbd_F21_<action>`	window reference
`kbd_F22_<action>`	window reference
`kbd_F23_<action>`	window reference
`kbd_F24_<action>`	window reference
`kbd_F25_<action>`	window reference
`kbd_UP_<action>`	window reference
`kbd_DOWN_<action>`	window reference
`kbd_LEFT_<action>`	window reference
`kbd_RIGHT_<action>`	window reference
`kbd_LEFT_SHIFT_<action>`	window reference
`kbd_RIGHT_SHIFT_<action>`	window reference
`kbd_LEFT_CONTROL_<action>`	window reference
`kbd_RIGHT_CONTROL_<action>`	window reference
`kbd_LEFT_ALT_<action>`	window reference
`kbd_RIGHT_ALT_<action>`	window reference
`kbd_TAB_<action>`	window reference, string="\t"
`kbd_ENTER_<action>`	window reference, string="\n"
`kbd_BACKSPACE_<action>`	window reference
`kbd_INSERT_<action>`	window reference
`kbd_DELETE_<action>`	window reference
`kbd_PAGEUP_<action>`	window reference
`kbd_PAGEDOWN_<action>`	window reference
`kbd_HOME_<action>`	window reference
`kbd_END_<action>`	window reference
`kbd_KEYPAD0_<action>`	window reference, string=`"0"`
`kbd_KEYPAD1_<action>`	window reference, string=`"1"`
`kbd_KEYPAD2_<action>`	window reference, string=`"2"`
`kbd_KEYPAD3_<action>`	window reference, string=`"3"`
`kbd_KEYPAD4_<action>`	window reference, string=`"4"`
`kbd_KEYPAD5_<action>`	window reference, string=`"5"`
`kbd_KEYPAD6_<action>`	window reference, string=`"6"`
`kbd_KEYPAD7_<action>`	window reference, string=`"7"`
`kbd_KEYPAD8_<action>`	window reference, string=`"8"`
`kbd_KEYPAD9_<action>`	window reference, string=`"9"`
`kbd_KEYPAD_DIVIDE_<action>`	window reference, string=`"/"`
`kbd_KEYPAD_MULTIPLY_<action>`	window reference, string=`"*"`
`kbd_KEYPAD_SUBTRACT_<action>`	window reference, string=`"-"`
`kbd_KEYPAD_ADD_<action>`	window reference, string=`"+"`
`kbd_KEYPAD_DECIMAL_<action>`	window reference, string=`"."`
`kbd_KEYPAD_EQUAL_<action>`	window reference, string=`"="`
`kbd_KEYPAD_ENTER_<action>`	window reference, string="\n"
`kbd_PRINT_SCREEN_<action>`	window reference
`kbd_NUM_LOCK_<action>`	window reference
`kbd_CAPS_LOCK_<action>`	window reference
`kbd_SCROLL_LOCK_<action>`	window reference
`kbd_PAUSE_<action>`	window reference
`kbd_LEFT_SUPER_<action>`	window reference
`kbd_RIGHT_SUPER_<action>`	window reference
`kbd_MENU_<action>`	window reference
`kbd_UNKNOWN_<action>`	window reference	Used when an unknown key is pressed

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