void CheckOffset(double x0, double y0, double x1, double y1, double segFrac, double offset,
double expectedX, double expectedY)
{
LineSegment seg = new LineSegment(x0, y0, x1, y1);
Coordinate p = seg.PointAlongOffset(segFrac, offset);
Assert.IsTrue(EqualsTolerance(new Coordinate(expectedX, expectedY), p, 0.000001));
}
/// <summary>
/// Adds a limited mitre join connecting the two reflex offset segments.
/// A limited mitre is a mitre which is beveled at the distance
/// determined by the mitre ratio limit.
/// </summary>
/// <param name="offset0">The first offset segment</param>
/// <param name="offset1">The second offset segment</param>
/// <param name="distance">The offset distance</param>
/// <param name="mitreLimit">The mitre limit ratio</param>
private void AddLimitedMitreJoin(
LineSegment offset0,
LineSegment offset1,
double distance,
double mitreLimit)
{
var basePt = _seg0.P1;
var ang0 = AngleUtility.Angle(basePt, _seg0.P0);
//var ang1 = AngleUtility.Angle(basePt, _seg1.P1);
// oriented angle between segments
var angDiff = AngleUtility.AngleBetweenOriented(_seg0.P0, basePt, _seg1.P1);
// half of the interior angle
var angDiffHalf = angDiff / 2;
// angle for bisector of the interior angle between the segments
var midAng = AngleUtility.Normalize(ang0 + angDiffHalf);
// rotating this by PI gives the bisector of the reflex angle
var mitreMidAng = AngleUtility.Normalize(midAng + Math.PI);
// the miterLimit determines the distance to the mitre bevel
var mitreDist = mitreLimit * distance;
// the bevel delta is the difference between the buffer distance
// and half of the length of the bevel segment
var bevelDelta = mitreDist * Math.Abs(Math.Sin(angDiffHalf));
var bevelHalfLen = distance - bevelDelta;
// compute the midpoint of the bevel segment
var bevelMidX = basePt.X + mitreDist * Math.Cos(mitreMidAng);
var bevelMidY = basePt.Y + mitreDist * Math.Sin(mitreMidAng);
var bevelMidPt = new Coordinate(bevelMidX, bevelMidY);
// compute the mitre midline segment from the corner point to the bevel segment midpoint
var mitreMidLine = new LineSegment(basePt, bevelMidPt);
// finally the bevel segment endpoints are computed as offsets from
// the mitre midline
var bevelEndLeft = mitreMidLine.PointAlongOffset(1.0, bevelHalfLen);
var bevelEndRight = mitreMidLine.PointAlongOffset(1.0, -bevelHalfLen);
if (_side == Positions.Left)
{
_segList.AddPt(bevelEndLeft);
_segList.AddPt(bevelEndRight);
}
else
{
_segList.AddPt(bevelEndRight);
_segList.AddPt(bevelEndLeft);
}
}
private static Coordinate[] GenerateSegmentCurve(Coordinate p0, Coordinate p1,
double width0, double width1)
{
var seg = new LineSegment(p0, p1);
var dist0 = width0 / 2;
var dist1 = width1 / 2;
var s0 = seg.PointAlongOffset(0, dist0);
var s1 = seg.PointAlongOffset(1, dist1);
var s2 = seg.PointAlongOffset(1, -dist1);
var s3 = seg.PointAlongOffset(0, -dist0);
Coordinate[] pts = { s0, s1, s2, s3, s0 };
return pts;
}