This comparison method is a vertical sorting test :
Sort two edges (edge1 and edge2, indeed), and sort them according to their intersection point
with the line l of equation x=abs.
intersects two edges returns null if there is no intersection
if the two edgse are colinear, returns the minimum intersection point,
if such a point exists.
Checks if the edges that are upper and lower than pRef in the list of
constraints that are linked to the boundary intersect the edge ed given
in parameter.
An edge is said to be encroached in a mesh if :
(The edge is a constraint OR an edge of the mesh' boundary)
AND there is a point lying in the circle it is the diameter of.
SHARE_EDGE_PART -
Static variable in class org.jdelaunay.delaunay.geometries.DEdge
Value returned by the intersects method when the two edges intersect in
more than one point (ie they are colinear and do not just share their extremities).
SHARE_EXTREMITY -
Static variable in class org.jdelaunay.delaunay.geometries.DEdge
Value returned by the intersects method when the two edges intersect in one
point that is an extremity for both of them.
This method will sort the edges contained in the ArrayList list by considering
their intersection point with the line of equation x=abs, where a is given
in parameter.