Therefore, regardless of what "cubic hair" refers to:
* Shaving hair does not change its underlying growth pattern. Hair grows from follicles beneath the skin. Shaving only cuts the hair at the surface. The shape, thickness, and direction of hair growth are determined by the hair follicle and your genetics.
* If "cubic hair" is a hairstyle: When the hair grows back after shaving, it will return to its natural texture and growth pattern. You can then restyle it into the "cubic" shape again.
* If "cubic hair" refers to some inherent unusual hair characteristic: This is unlikely, but even if it did, shaving wouldn't alter the underlying biology. The hair would likely grow back with the same unusual characteristics.
If you can provide more information about what you mean by "cubic hair," I might be able to give a more specific answer.