public void FindCutLinesThreePointSetsTest()
{
var ret = HamSandwich.FindCutLines(m_points1, m_points2, m_points3);
var expX = new FloatInterval(-1, 1);
var expY = new FloatInterval(-2, 2);
Assert.AreEqual(1, ret.Count);
Assert.IsTrue(expX.ContainsEpsilon(ret[0].Slope));
Assert.IsTrue(expY.ContainsEpsilon(ret[0].HeightAtYAxis));
}
public void FindCutlinesInDualThreeRegionsTest()
{
var faces1 = HamSandwich.MiddleFaces(m_dcel1, m_lines1);
var faces2 = HamSandwich.MiddleFaces(m_dcel2, m_lines2);
var faces3 = HamSandwich.MiddleFaces(m_dcel3, m_lines3);
var ret = HamSandwich.FindCutlinesInDual(faces1, faces2, faces3);
var expX = new FloatInterval(-1, 1);
var expY = new FloatInterval(-2, 2);
Assert.AreEqual(1, ret.Count);
Assert.IsTrue(expX.ContainsEpsilon(ret[0].Slope));
Assert.IsTrue(expY.ContainsEpsilon(ret[0].HeightAtYAxis));
}
/// <summary>
/// Returns a halfedge of the leftmost middle face.
/// </summary>
/// <param name="m_dcel"></param>
/// <param name="m_dualLines"></param>
/// <returns></returns>
private static HalfEdge LeftMostMiddleHalfEdge(DCEL m_dcel, IEnumerable <Line> m_dualLines)
{
var bbox = m_dcel.InitBoundingBox.Value;
// get all intersections with left line of bounding box
var leftLine = new Line(new Vector2(bbox.xMin, bbox.yMin), new Vector2(bbox.xMin, bbox.yMax));
var intersections = m_dualLines
.Where(l => !l.IsVertical)
.Select(l => leftLine.Intersect(l).Value)
.ToList();
// sort on y value
intersections.Sort((v1, v2) => v1.y.CompareTo(v2.y));
// find edge between middle intersections
var middleIntersectBot = intersections[intersections.Count / 2 - 1];
var middleIntersectTop = intersections[intersections.Count / 2];
var edgeInterval = new FloatInterval(middleIntersectBot.y, middleIntersectTop.y);
// get corresponding halfedge in dcel
HalfEdge workingEdge;
if (bbox.yMin < edgeInterval.Min && bbox.yMax > edgeInterval.Max)
{
// both intersections contained on left segment of bounding box
workingEdge = DCEL.Cycle(m_dcel.OuterFace.InnerComponents[0])
.FirstOrDefault(e => e.From.Pos.x == bbox.xMin &&
edgeInterval.ContainsEpsilon(e.From.Pos.y) &&
edgeInterval.ContainsEpsilon(e.To.Pos.y));
}
else if (bbox.yMin >= edgeInterval.Min)
{
// bottom intersection lies below left segment
// find halfedge pointing to bottom left corner
workingEdge = DCEL.Cycle(m_dcel.OuterFace.InnerComponents[0])
.FirstOrDefault(e => MathUtil.Equals(e.From.Pos, new Vector2(bbox.xMin, bbox.yMin)));
// traverse outer cycle until we find line with the corresponding bottom intersection
while (workingEdge.Twin.Prev.Segment.Line.IsVertical ||
!MathUtil.EqualsEps(workingEdge.Twin.Prev.Segment.Line.Intersect(leftLine).Value, middleIntersectBot))
{
workingEdge = workingEdge.Next;
}
}
else
{
// top intersection lies above left segment
// find halfedge pointing away from top left corner
workingEdge = DCEL.Cycle(m_dcel.OuterFace.InnerComponents[0])
.FirstOrDefault(e => MathUtil.Equals(e.To.Pos, new Vector2(bbox.xMin, bbox.yMax)));
// traverse outer cycle until we find line with the corresponding top intersection
while (workingEdge.Twin.Next.Segment.Line.IsVertical ||
!MathUtil.EqualsEps(workingEdge.Twin.Next.Segment.Line.Intersect(leftLine).Value, middleIntersectTop))
{
workingEdge = workingEdge.Prev;
}
}
// middle edge should always exist
if (workingEdge == null)
{
throw new GeomException("working edge not found");
}
// return twin (edge of middle face, not outer face)
return(workingEdge.Twin);
}