SoFieldSensor with camera position

/*-------------------------------------------------------------- * Sense changes to a viewer's camera's position. *------------------------------------------------------------*/#include <Inventor/SoDB.h>#include <Inventor/Win/SoWin.h>#include <Inventor/Win/viewers/SoWinExaminerViewer.h>#include <Inventor/nodes/SoCamera.h>#include <Inventor/nodes/SoSeparator.h>#include <Inventor/sensors/SoFieldSensor.h>#ifdef WIN32# include "print.h"#endif// Callback that reports whenever the viewer's position changes.static voidcameraChangedCB(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]); }intmain(int argc, char **argv){ if (argc != 2) { fprintf(stderr, "Usage: %s filename.iv/n", argv[0]); exit(1); } HWND myWindow = SoWin::init(argv[0]); if (myWindow == NULL) exit(1); SoInput inputFile; if (inputFile.openFile(argv[1]) == FALSE) { fprintf(stderr, "Could not open file %s/n", argv[1]); exit(1); } SoSeparator *root = SoDB::readAll(&inputFile); root->ref(); SoWinExaminerViewer *myViewer = new SoWinExaminerViewer(myWindow); myViewer->setSceneGraph(root); myViewer->setTitle("Camera Sensor"); myViewer->show(); // Get the camera from the viewer, and attach a // field sensor to its position field: SoCamera *camera = myViewer->getCamera(); SoFieldSensor *mySensor = new SoFieldSensor(cameraChangedCB, camera); mySensor->attach(&camera->position); SoWin::show(myWindow); SoWin::mainLoop(); return 0;}