Offset of starting point from 12 o'clock in radians. Offset
is applied clockwise or anticlockwise depending on value of direction.
direction
1, clockwise; -1, anticlockwise
clip
Should drawing be clipped to the extent of the plot panel? A
setting of "on" (the default) means yes, and a setting of "off"
means no. For details, please see coord_cartesian().