[GUI] Support gui.arrow_field() and gui.point_field() for small resolution vector / scalar field visualization (#1763)
[GUI] Support gui.arrow_field() and gui.point_field() for small resolution vector / scalar field visualization (#1763)

* tmp

* clear
yuanming-hu/taichi,yuanming-hu/taichi,yuanming-hu/taichi,yuanming-hu/taichi