public Polygon Cleaned(double distance = 1.415)
{
// distance = proximity in units/pixels below which vertices will be stripped.
// Default ~= sqrt(2) so when adjacent vertices or semi-adjacent vertices have
// both x & y coords within 1 unit, then the second vertex will be stripped.
var pointCount = Count;
if (pointCount == 0)
{
return(new Polygon());
}
var outputPoints = new OutputPoint[pointCount];
for (var i = 0; i < pointCount; ++i)
{
outputPoints[i] = new OutputPoint();
}
for (var i = 0; i < pointCount; ++i)
{
outputPoints[i].Point = this[i];
outputPoints[i].Next = outputPoints[(i + 1) % pointCount];
outputPoints[i].Next.Prev = outputPoints[i];
outputPoints[i].Index = 0;
}
var distSqrd = distance * distance;
var op = outputPoints[0];
while (op.Index == 0 && op.Next != op.Prev)
{
if (GeometryHelper.PointsAreClose(op.Point, op.Prev.Point, distSqrd))
{
op = ExcludeOutputPoint(op);
pointCount--;
}
else if (GeometryHelper.PointsAreClose(op.Prev.Point, op.Next.Point, distSqrd))
{
ExcludeOutputPoint(op.Next);
op = ExcludeOutputPoint(op);
pointCount -= 2;
}
else if (GeometryHelper.SlopesNearCollinear(op.Prev.Point, op.Point, op.Next.Point, distSqrd))
{
op = ExcludeOutputPoint(op);
pointCount--;
}
else
{
op.Index = 1;
op = op.Next;
}
}
if (pointCount < 3)
{
pointCount = 0;
}
var result = new Polygon(pointCount);
for (var i = 0; i < pointCount; ++i)
{
result.Add(op.Point);
op = op.Next;
}
return(result);
}