Code:
new Float:flAngle[3];
entity_get_vector(character[id], EV_VEC_v_angle, flAngle);
flAngle[1] += 180;
if( flAngle[1] > 360.0 )
{
flAngle[1] -= 360.0;
}
entity_set_vector(character[id], EV_VEC_v_angle, Float:{0.0,0.0,0.0});
entity_set_vector(character[id], EV_VEC_angles, flAngle);
entity_set_int(character[id], EV_INT_fixangle, 1);