Buddhism on suicide

I want to know how *suicide* is viewed in Buddhism. I know that it is not viewed positively, but I want to know why. Is it because it brings grief to others? Is that the only reason? Or there is something else..? I think that if you die happily in a calm state because you wish to, there is no negative energy within you.. so I don't understand why suicide is such a bad thing. *(the reasons I think are the grief that will bring to the family and that one's negative energy will linger)* Buddhism also varies among countries and cultures (I'm from the East Asia), but I believe it all began with the core teachings of Buddha and I just want to learn his teachings. Thank you.