📅  最后修改于: 2022-03-11 15:04:34.094000             🧑  作者: Mango
# General formula for rotating around origin is
xNew = x * cos(a) - y * sin(a)
yNew = x * sin(a) + y * cos(a)
# For 90 degrees it becomes
xNew = -y
yNew = x