1. User Interaction Chapters 10, 12, 13, 15

2. Events Events are actions applied to the graph Each node implements its own behavior When node is found to handle the event, the graph traversing stops.

3. Keyboard Events Create an event node. Create a callback function Add the node to the graph (typically to root) Callback nodes are written to file, but without the event they process Example …

4. Keyboard Events #include // Callback function void keyEvent(void* userData, SoEventCallback* eventCallBack){ const SoEvent *curEvent = eventCallBack->getEvent(); if(SO_KEY_PRESS_EVENT(curEvent, Q)) { exit(1); } // Main file SoEventCallback* switchEventCallBack = new SoEventCallback; root->addChild(switchEventCallBack); switchEventCallBack->addEventCallback(SoKeyboardEvent::getClassTypeId(), keyEvent, root); switchEventCallBack->removeEventCallback(SoKeyboardEvent::getClassTypeId(), keyEvent, root);

5. Mouse events Defined similarly to keyboard events –SoMouseButtonEvent and SoLocation2Event However SoWinExaminerViewer blocks the mouse events. To unblock them – check “arrow” button Example …

6. Selection of nodes SoSelection –Defined in SoSelection.h –Derived from SoGroup –Has a built-in method to handle mouse events –Responses to mouse click on object –Inserted near root (above, below or instead) –Used for manipulators

7. SoSelection SoSelection * root = new SoSelection; root->addSelectionCallback(selectionCallback, NULL); root->addDeselectionCallback(deselectionCallback, NULL); // ----------------------------------------------------------------- // void selectionCallback(void *, SoPath *selectionPath) { SoTranslation *tr = (SoTranslation *)selectionPath->getNodeFromTail( 1); SbVec3f a = tr->translation.getValue(); std::cout<< a.getValue(); }

8. Sensors Special class of nodes Data sensors –Monitor a part of database and inform the application when that part changes Time sensors –Response to time events (inner events of Inventor)

9. Data sensors SoFieldSensor (attached to a field) SoNodeSensor (attached to a node) SoPathSensor (attached to a path)

10. Data sensors - example // Callback that reports whenever the viewer's position changes. static void cameraChangedCB(void *data, SoSensor *) { SoCamera *viewerCamera = (SoCamera *)data; SbVec3f cameraPosition = viewerCamera->position.getValue(); printf("Camera position: (%g,%g,%g)\n", cameraPosition[0], cameraPosition[1], cameraPosition[2]); } // main function SoCamera *camera = myViewer->getCamera(); SoFieldSensor *mySensor = // define callback and its input new SoFieldSensor(cameraChangedCB, camera); // Attach callback to camera position mySensor->attach(&camera->position);

11. Sequence for Data Sensors // Construct the sensor SoSensor *sensor = new SoSensor( func, data); // Function must be static void func( void *, SoSensor *) // since it obtains pointer to the sensor // Set the priority of the sensor // 0 highest // 100 is default priority (lowest) sensor->setPriority(priority number); // Attach the sensor to a field, node or path sensor->attach(pointer to object);

12. Using the trigger node and field You can use –getTriggerField(); –getTriggerNode(); –getTriggerPath(); For 0 priority sensors Use setTriggerPathFlag() –Sets trigger path flag to true –Saving path is expensive

13. Using the trigger node and field // This function prints a message whenever changes are made to the scene graph. // The sensor should be attached to root // Sensor callback function: static void rootChangedCB(void *, SoSensor *s) { // We know the sensor is really a data sensor: SoDataSensor *mySensor = (SoDataSensor *)s; SoNode *changedNode = mySensor->getTriggerNode(); SoField *changedField = mySensor->getTriggerField(); // Print the data printf("The node named '%s' changed\n",changedNode->getName().getString()); if (changedField != NULL) { SbName fieldName; changedNode->getFieldName(changedField, fieldName); printf(" (field %s)\n", fieldName.getString()); } else printf(" (no fields changed)\n"); }

14. Time sensors SoAlarmSensor –Goes off at a specific time SoTimerSensor –Goes off at intervals

15. Example // Rotate flag every minute static void raiseFlagCallback(void *data, SoSensor *) { // We know data is really a SoTransform node: SoTransform *flagAngleXform = (SoTransform *)data; // Rotate flag by 90 degrees about the z axis: flagAngleXform->rotation.setValue(SbVec3f(0,0,1), M_PI/2); } // Main function SoTransform *flagXform = new SoTransform; // Create an alarm that will call the flag-raising callback: SoAlarmSensor *myAlarm = new SoAlarmSensor(raiseFlagCallback, flagXform); myAlarm->setTimeFromNow(60.0); myAlarm->schedule();

16. Time sensors sequence Construct Set the callback Set the timing before scheduling Schedule using schedule() Delete when finished

17. Setting the timing For alarm: sensor->setTime(time); sensor->setTimerFromNow(time); For timer: Interval: sensor->setInterval(interval); First time (default is now): sensor->setBaseTime(time);

18. Example Rotate the flag with different frequencies Two frequencies are available –1Hz –10Hz Exchange the frequencies every 5 sec

19. Example SoRotation *myRotation = new SoRotation; root->addChild(myRotation); root->addChild(myFlag); SoTimerSensor *exchangeSensor = new SoTimerSensor(exchangeFrequencies, rotatingSensor); SoTimerSensor *rotatingSensor = new SoTimerSensor(rotateCallback, myRotation); exchangeSensor ->setInterval(5.0); // once per 5 seconds exchangeSensor ->schedule(); rotatingSensor->setInterval(1.0); //scheduled once per second rotatingSensor->schedule();

20. Example // This function is called once every 5 seconds, and // reschedules the other sensor. static void exchangeFrequencies(void *data, SoSensor *){ SoTimerSensor *rotatingSensor = (SoTimerSensor *)data; rotatingSensor->unschedule(); if (rotatingSensor->getInterval() == 1.0) rotatingSensor->setInterval(1.0/10.0); else rotatingSensor->setInterval(1.0); rotatingSensor->schedule(); } // This function is called either 10 times/second or once every // second; the scheduling changes every 5 seconds (see below): static void rotateCallback(void *data, SoSensor *){ // Rotate an object... SoRotation *myRotation = (SoRotation *)data; SbRotation currentRotation = myRotation->rotation.getValue(); currentRotation = SbRotation(SbVec3f(0,0,1), M_PI/90.0) *currentRotation; myRotation->rotation.setValue(currentRotation); }