A TouchSensor node can supply touch events

DEF Toggle Script {
    field    SFBool on TRUE
    eventIn  SFBool set_active
    eventOut SFBool on_changed
    url "vrmlscript:
        function set_active( b, ts ) {
            // ignore button releases
            if ( b  == FALSE ) return;

            // toggle on button presses
            if ( on == TRUE  ) on = FALSE;
            else               on = TRUE;
            on_changed = on;
        }"
}