in pytheas-core/src/main/resources/js/d3/d3.geom.js [289:318]
d3_voronoi_tessellate(vertices, function(e) {
var s1,
s2,
x1,
x2,
y1,
y2;
if (e.a === 1 && e.b >= 0) {
s1 = e.ep.r;
s2 = e.ep.l;
} else {
s1 = e.ep.l;
s2 = e.ep.r;
}
if (e.a === 1) {
y1 = s1 ? s1.y : -1e6;
x1 = e.c - e.b * y1;
y2 = s2 ? s2.y : 1e6;
x2 = e.c - e.b * y2;
} else {
x1 = s1 ? s1.x : -1e6;
y1 = e.c - e.a * x1;
x2 = s2 ? s2.x : 1e6;
y2 = e.c - e.a * x2;
}
var v1 = [x1, y1],
v2 = [x2, y2];
polygons[e.region.l.index].push(v1, v2);
polygons[e.region.r.index].push(v1, v2);
});