void gis_viewer_get_rotation(GisViewer *viewer, gdouble *x, gdouble *y, gdouble *z);
void gis_viewer_rotate (GisViewer *viewer, gdouble x, gdouble y, gdouble z);
void gis_viewer_get_rotation(GisViewer *viewer, gdouble *x, gdouble *y, gdouble *z);
void gis_viewer_rotate (GisViewer *viewer, gdouble x, gdouble y, gdouble z);