move into
https://github.com/kyorohiro/doc_2dgamearrow-up-right
https://www.gitbook.com/book/kyorohiro/doc_2dgame/detailsarrow-up-right
https://github.com/kyorohiro/doc_2dgame/tree/master/demo/ironheartarrow-up-right
(-)------------(+) x (-) | | | (+) y
Last updated 5 years ago
clock (-90) | | | | | ---------------(0) | | | | | (90)
(0) | | (-)-------|----------(+) ( ^ )
