For what you want, you can do:
var cam_height = 125;
var cam_dist = 700;
VECTOR temp;
vec_set(&temp, me.x);
temp.z += cam_height;
temp.x -= cam_dist * cos(me.pan);
temp.y -= cam_dist * sin(me.pan);
vec_set(camera.x, &temp);
camera.pan = me.pan ;
But it is very basic for a third person camera, you can smooth the camera movement.
PS : You can replace me by player or whatever entity you want to follow.
