this is the code:

function handle_camera()
{

camera.x = my.x - fcos(my.pan, 120);
camera.y = my.y - fsin(my.pan, 120);
camera.z = my.z + 30;

camera.pan = my.pan;
camera.tilt += (mouse_force.y*5);
//////
//////
if(camera.tilt > 90)
{
camera.tilt = 90;
}
else if (camera.tilt < -90)
{
camera.tilt = -90;
}

}