static CurveIntersectionInfo GetIntersectionInfoFromCurves(Curve c1, Curve c2)
{
// Utility function to test for intersection from convex polygon
bool StrictlyInsideConvexPolygon(Double2[] poly, Double2 pt)
{
var length = poly.Length;
for (int i = 0; i < length; i++)
{
var ik = (i + 1) % length;
if (DoubleUtils.RoughlyEquals(poly[i], poly[ik]))
{
continue;
}
if ((poly[ik] - poly[i]).Cross(pt - poly[i]) <= 0)
{
return(false);
}
}
return(true);
}
// Utility function to test for intersection with curve
bool CurveIntersects(Double2[] poly, Curve curve)
{
var length = poly.Length;
for (int i = 0; i < length; i++)
{
var ik = (i + 1) % length;
if (DoubleUtils.RoughlyEquals(poly[i], poly[ik]))
{
continue;
}
if (curve.IntersectionsWithSegment(poly[i], poly[ik]).Any(t => t >= 0 && t <= 1))
{
return(true);
}
}
return(false);
}
// Get the curves' enclosing polygons
var p1 = GeometricUtils.EnsureCounterclockwise(c1.EnclosingPolygon);
var p2 = GeometricUtils.EnsureCounterclockwise(c2.EnclosingPolygon);
// If there is no intersection, no info
if (!GeometricUtils.PolygonsOverlap(p1, p2, true))
{
return(null);
}
return(new CurveIntersectionInfo
{
InteriorPoints1 = p2.Where(p => StrictlyInsideConvexPolygon(p1, p)).ToArray(),
InteriorPoints2 = p1.Where(p => StrictlyInsideConvexPolygon(p2, p)).ToArray(),
CurveIntersects1 = CurveIntersects(p2, c1),
CurveIntersects2 = CurveIntersects(p1, c2)
});
}
