I got it but i am wondering how to make him stop when he reach behind the model?
here is the code...

entity* stand_ent;
entity* rotate_ent;
var move_speed;

action model_stand
{
stand_ent = me;
}

action rotate_model
{
rotate_ent = me;
while(1)
{


if(stand_ent != 0)
{
vec_set(temp, stand_ent.x);
vec_sub(temp, my.x);
vec_to_angle(my.pan, temp);
my.tilt = 0;
my.roll = 0;
move_speed.x = 0;
move_speed.y = 2*time;
c_move(my,move_speed,nullvector,ignore_me + glide);
}
wait(1);
}
}