credits Magnus Hoff
tut1: https://plus.google.com/+MagnusHoff/posts/9gxSUZMJUF2 tut2: https://plus.google.com/+MagnusHoff/posts/TardBAAtq4e tut3: https://plus.google.com/+MagnusHoff/posts/LS8T4hTYWPm tut4: https://plus.google.com/+MagnusHoff/posts/PfXkVfSENmb tut5: https://plus.google.com/+MagnusHoff/posts/VcfnDyjS5RU tut6: https://plus.google.com/+MagnusHoff/posts/domAeYdQ4Bp