/// <summary>
/// Squash path sections on one axis that share common ground
/// </summary>
private IEnumerable <PathSection> Squash(IEnumerable <PathSection> sections)
{
var orderedSections = sections
.OrderBy(x => x.BottomLeft.X)
.ThenBy(x => x.BottomLeft.Y)
.ToList();
var squashed = new List <PathSection>();
var current = orderedSections.First();
foreach (var s in orderedSections)
{
if (s.BottomLeft.X > current.TopRight.X || s.BottomLeft.Y > current.TopRight.Y)
{
squashed.Add(current);
current = s;
}
else
{
var mx = Math.Max(current.TopRight.X, s.TopRight.X);
var my = Math.Max(current.TopRight.Y, s.TopRight.Y);
current = new PathSection(current.BottomLeft, new Point(mx, my));
}
}
if (current != null)
{
squashed.Add(current);
}
return(squashed);
}
/// <summary>
/// Get intersection of two path sections
/// </summary>
/// <returns>Intersection, if exists, null otherwise</returns>
private PathSection GetIntersection(PathSection a, PathSection b)
{
if (a.Horizontal == b.Horizontal)
{
// sections are parallel to each other
// there can be [0, Min(a.Length, b.Length)] places in common
if (a.Horizontal)
{
// horizontal lines
if (a.BottomLeft.Y == b.BottomLeft.Y)
{
var bl = Math.Max(a.BottomLeft.X, b.BottomLeft.X);
var tr = Math.Min(a.TopRight.X, b.TopRight.X);
// return intersection if exists
return(bl <= tr ? new PathSection(new Point(bl, a.BottomLeft.Y), new Point(tr, a.BottomLeft.Y)) : null);
}
else
{
// lines are in different Y axis, there cannot be any intersection
return(null);
}
}
else
{
// vertical lines
if (a.BottomLeft.X == b.BottomLeft.X)
{
var bl = Math.Max(a.BottomLeft.Y, b.BottomLeft.Y);
var tr = Math.Min(a.TopRight.Y, b.TopRight.Y);
// return intersection if exists
return(bl <= tr ? new PathSection(new Point(a.BottomLeft.X, bl), new Point(a.BottomLeft.X, tr)) : null);
}
else
{
// lines are in different X axis, there cannot be any intersection
return(null);
}
}
}
else
{
// sections are perpendicular to each other
// there can be [0, 1] places in common
var h = a.Horizontal ? a : b;
var v = a.Horizontal ? b : a;
var c1 = (h.BottomLeft.X <= v.BottomLeft.X) && (v.BottomLeft.X <= h.TopRight.X);
var c2 = (v.BottomLeft.Y <= h.BottomLeft.Y) && (h.BottomLeft.Y <= v.TopRight.Y);
var ip = new Point(v.BottomLeft.X, h.BottomLeft.Y);
return(c1 && c2 ? new PathSection(ip, ip) : null);
}
}