Diagonals
When measuring distance, count the first diagonal as 1 square, the second as 2 squares, the third as 1, the fourth as 2, and so on. You can’t move diagonally past a hard corner (such as the corner of a building or starship or the side of a doorframe), but you can move diagonally past a creature (even an opponent) or less rigid objects, such as plant life.
Source
Core Rulebook pg. 256
