Revert "the mistake of calulating collision is cleared."

This reverts commit 738f94acab8de0f8f2ae498b00afa7510a385762.
Revert "Revert "the mistake of calulating collision is cleared.""

This reverts commit 6de5a8af1a451c83b05b2896060e2685eaaab4ae.
something was wrong
what fucking is this...