Added in 1.9.4
$onpoly(n1,n2,x,y,x,y,...)
Returns $true if two polygons overlap, otherwise $false.
Parameters
n1 - Number of points in the first polygon.
n2 - Number of points in the second polygon.
x - First x coordinate.
y - First y coordinate.
x - Second x coordinate.
y - Second y coordinate.
... - Additional coordinates.