public double DistanceSquared(Vector2D p, out int iNearSeg, out double fNearSegT)
{
iNearSeg = -1;
fNearSegT = double.MaxValue;
double dist = double.MaxValue;
int N = vertices.Count;
for (int vi = 0; vi < N; ++vi)
{
Segment2d seg = new Segment2d(vertices[vi], vertices[(vi + 1) % N]);
double t = (p - seg.Center).Dot(seg.Direction);
double d = double.MaxValue;
if (t >= seg.Extent)
{
d = seg.P1.DistanceSquared(p);
}
else if (t <= -seg.Extent)
{
d = seg.P0.DistanceSquared(p);
}
else
{
d = (seg.PointAt(t) - p).LengthSquared;
}
if (d < dist)
{
dist = d;
iNearSeg = vi;
fNearSegT = t;
}
}
return(dist);
}
public static Segment2d Project(this Segment2d _host, Segment2d _seg)
{
//project each end point
double t0 = _host.Project(_seg.P0);
double t1 = _host.Project(_seg.P1);
t0 = MathUtil.Clamp(t0, -1.0 * _host.Extent, _host.Extent);
t1 = MathUtil.Clamp(t1, -1.0 * _host.Extent, _host.Extent);
if (t0.IsAlmostEqualByDifference(t1))
{
return(new Segment2d(Vector2d.Zero, Vector2d.Zero));
}
var p0 = _host.PointAt(t0);
var p1 = _host.PointAt(t1);
return(new Segment2d(p0, p1));
}
// yikes not robust at all!!
protected List <Segment2d> compute_polygon_ray_spans(GeneralPolygon2d poly, Segment2d ray, Vector2d axis_origin, Vector2d axis, double axisT, SegmentSet2d segments)
{
List <double> hits = new List <double>(); // todo reusable buffer
segments.FindAllIntersections(ray, hits, null, null, false);
hits.Sort();
bool clean = true;
for (int i = 0; i < hits.Count - 1 && clean; ++i)
{
if (hits[i + 1] - hits[i] < MathUtil.Epsilonf)
{
clean = false;
}
}
if (!clean)
{
hits = extract_valid_segments(poly, ray, hits);
}
if (hits.Count % 2 != 0)
{
throw new Exception("DenseLineFill.ComputeAllSpans: have not handled hard cases...");
}
List <Segment2d> spans = new List <Segment2d>();
for (int i = 0; i < hits.Count / 2; ++i)
{
Vector2d p0 = ray.PointAt(hits[2 * i]);
Vector2d p1 = ray.PointAt(hits[2 * i + 1]);
spans.Add(new Segment2d(p0, p1));
}
return(spans);
}
/// <summary>
/// hits is a sorted list of t-values along ray. This function
/// tries to pull out the valid pairs, ie where the segment between the
/// pair is inside poly.
///
/// numerical problems:
/// - no guarantee that all intersection t's are in hits list
/// (although we are being conservative in SegmentSet2d, testing extent+eps)
/// - poly.Contains() could return false for points very near to border
/// (in unfortunate case this means we discard valid segments. in
/// pathological case it means we produce invalid ones)
/// </summary>
List <double> extract_valid_segments(GeneralPolygon2d poly, Segment2d ray, List <double> hits)
{
double eps = MathUtil.Epsilonf;
List <double> result = new List <double>();
int i = 0;
int j = i + 1;
while (j < hits.Count)
{
// find next non-dupe
while (j < hits.Count && hits[j] - hits[i] < eps)
{
j++;
}
if (j == hits.Count)
{
continue;
}
// ok check if midpoint is inside or outside
double mid_t = (hits[i] + hits[j]) * 0.5;
Vector2d mid = ray.PointAt(mid_t);
// not robust...eek
bool isInside = poly.Contains(mid);
if (isInside)
{
// ok we add this segment, and then we start looking at next point (?)
result.Add(hits[i]);
result.Add(hits[j]);
i = j + 1;
j = i + 1;
}
else
{
// ok we were not inside, so start search at j
i = j;
j++;
}
}
return(result);
}
public Vector2D PointAt(int iSegment, double fSegT)
{
Segment2d seg = new Segment2d(vertices[iSegment], vertices[(iSegment + 1) % vertices.Count]);
return(seg.PointAt(fSegT));
}
