/* Trackball Handler */
void trackball_handler(int event,int xx,int yy) {
float matrix[4][4];
if ( event == FL_PUSH ) {
x_ang = xx ;
y_ang = yy ;
trackball.rotate( 0,0,0,0 ) ;
}
else if (( event == FL_DRAG ) ) {
trackball.rotate((2.0 * x_ang - screen_width) / float(screen_width),
(screen_height - 2.0 * y_ang) / float(screen_height),
(2.0 * xx - screen_width) / float(screen_width),
(screen_height - 2.0 * yy) / float(screen_height));
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
trackball.rotationMatrix(matrix);
glMultMatrixf((float *)matrix);
x_ang = xx ;
y_ang = yy ;
glutPostRedisplay() ;
}
}
