public bool Contains(LineSeg ll)
{
Vector s = ll.Start; Vector e = ll.End;
return(m_xmin <= s.X && s.X <= m_xmax &&
m_xmin <= e.X && e.X <= m_xmax &&
m_ymin <= s.Y && s.Y <= m_ymax &&
m_ymin <= e.Y && e.Y <= m_ymax);
}
/// Intersection test for line segments..
public bool Intersects(LineSeg l)
{
// Seperating axis method.
Vector sp = l.Start;
Vector ep = l.End;
Vector dir = l.Dir;
// Projection onto the x & y axis & check for overlap
if (!intervalsOverlap(sp.X, ep.X, m_xmin, m_xmax))
{
return(false);
}
if (!intervalsOverlap(sp.Y, ep.Y, m_ymin, m_ymax))
{
return(false);
}
// Test line-sidedness
Vector ll = new Vector(m_xmin, m_ymin) - sp;
int side = dir.Side(ll);
if (side == 0) // the point lies right on the line
{
return(true);
}
Vector lr = new Vector(m_xmax, m_ymin) - sp;
if (side != dir.Side(lr))
{
return(true);
}
Vector ul = new Vector(m_xmin, m_ymax) - sp;
if (side != dir.Side(ul))
{
return(true);
}
Vector ur = new Vector(m_xmax, m_ymax) - sp;
if (side != dir.Side(ur))
{
return(true);
}
// If we got here, all 4 corners lie on the same side of the line
return(false);
}
/// Overlay two lines with given tolerances.
/// (see Vector.GetParTolerance for the parallel tolerance; the
/// distance tolerance should be a distance^2.)
/// Outputs are: the overlap itself,
/// any leftover bits prior to the overlap,
/// any leftover bits afterwards,
/// and two booleans indicating which lineseg 'owns' the leftovers.
public static void Overlay(LineSeg a,
LineSeg b,
double par_tolerance,
double sep_dist_squared,
out LineSeg prior,
out bool a_is_prior,
out LineSeg overlap,
out LineSeg after,
out bool a_is_after)
{
prior = null; overlap = null; after = null;
a_is_prior = false; a_is_after = false;
// If they aren't parallel, we're done.
if (!Vector.AreParallel(a.Dir, b.Dir, par_tolerance))
{
return;
}
double a_tval; // the t value for line a where the overlap with b may start
double distsq = a.PointDistanceSq(b.Start, out a_tval);
if (distsq > sep_dist_squared) // too far away
{
return;
}
double a_nd_tval; // t value where the end of b overlaps line a
distsq = a.PointDistanceSq(b.End, out a_nd_tval);
if (distsq > sep_dist_squared) // too far away
{
return;
}
// The lines themselves are overlapping but the line
// segments might not be, in which case neither of b's endpoints
// will generate a tval in the [0,1] interval.
double st_t = Math.Min(a_tval, a_nd_tval); // Order things so a
double nd_t = Math.Max(a_tval, a_nd_tval); // line from st_t to
// nd_t will be
// parallel to A.
// If the overlap is completely outside of a, done:
if (st_t > 1.0)
{
return;
}
if (nd_t < 0.0)
{
return;
}
// There's an overlap.
// Threshold a_tval and a_nd_tval into [0,1] for the overlapping portion.
double clamp_st_t = Math.Max(st_t, 0.0);
double clamp_nd_t = Math.Min(nd_t, 1.0);
overlap = new LineSeg(a.Start + (clamp_st_t * a.Dir),
((clamp_nd_t - clamp_st_t) * a.Dir));
// Don't return overlaps shorter than the error distance...
if (overlap.Dir.LengthSq < sep_dist_squared)
{
overlap = null;
return;
}
// Find any leftover, non-overlapping portions of a and b:
if (st_t < 0.0) // some of line b is before line a's start
{
prior = FromEndpoints(a.Start + (st_t * a.Dir), a.Start);
a_is_prior = false;
}
else if (st_t > 0.0) // some of line a is left over
{
prior = FromEndpoints(a.Start, a.Start + (st_t * a.Dir));
a_is_prior = true;
}
if (nd_t > 1.0) // Some of 'b' is after a's end:
{
after = FromEndpoints(a.End, a.Start + (nd_t * a.Dir));
a_is_after = false;
}
else if (nd_t < 1.0) // some of 'a' leftover.
{
after = FromEndpoints(a.Start + (nd_t * a.Dir), a.End);
a_is_after = true;
}
// Null out the leftovers if they aren't larger than the tolerance:
if (prior != null && prior.Dir.LengthSq < sep_dist_squared)
{
prior = null;
}
if (after != null && after.Dir.LengthSq < sep_dist_squared)
{
after = null;
}
}
