for the perspective you want lock the cameras pan and tilt outside of a while loop and move the cam around inside a while loop like so


camera.tilt=-60;
camera.pan=315;


while (1)
{

camera.x+=6*(key_cul-key_cur)*time_step;
camera.y+=6*(key_cud-key_cuu)*time_step;

wait(1);
}


at least that should be close to the angles you want , judging from the pic