super simple question!

first,hi@all
then,i want to conver sun 3Dpos(xyz)to 2Dpos(xy),
and i tried vec_to_screen(sun_pos,camera),and heres my problem:
how can i get 2Dposition's vector?
like
var scr_x;
var scr_y;
scr_x=vec_to_screen(sun_pos,camera).x //ofcourse this wont work
or somethin else?
thx !

The function returns an normal Vector with z = 0.

He means use
VECTOR scr_pos;
scr_pos = vec_to_screen(sun_pos,camera); //scr_pos.z will always be zero

thx!
and one more:
does that means:
1:scr_pos .x=Valuable data converted by function
2:scr_pos .y=Valuable data converted by function
3:scr_pos .z=zero