You also can change this (if you don`t need wpos):

vec_for_vertex(wpos, player, 23);
my.x = wpos.x;
my.y= wpos.y;
my.z = wpos.z;

to:

vec_for_vertex(my.x, player, 23);
-----------------------------
also:

my.x = wpos.x;
my.y= wpos.y;
my.z = wpos.z;

to:

vec_set (my.x,wpos);