void PS_circle(PSDoc *psdoc, float x, float y, float radius)
Draws a circle with its middle point at
y). The circle starts
and ends at position
y). If this function is called outside a path it
will start a new path. If it is called within a path it will add the
circle as a subpath. If the last drawing operation does not end in point
y) then there will be a gab in the path.