/// <summary>
/// Non-allocating version of CalculateDiagram.
///
/// I guess it's not strictly true that it generates NO garbage, because
/// it might if it has to resize internal buffers, but all buffers are
/// reused from invocation to invocation.
/// </summary>
public void CalculateDiagram(IList <Vector2> inputVertices, ref VoronoiDiagram result)
{
// TODO: special case for 1 points
// TODO: special case for 2 points
// TODO: special case for 3 points
// TODO: special case for collinear points
if (inputVertices.Count < 3)
{
throw new NotImplementedException("Not implemented for < 3 vertices");
}
if (result == null)
{
result = new VoronoiDiagram();
}
var trig = result.Triangulation;
result.Clear();
Profiler.BeginSample("Delaunay triangulation");
delCalc.CalculateTriangulation(inputVertices, ref trig);
Profiler.EndSample();
pts.Clear();
var verts = trig.Vertices;
var tris = trig.Triangles;
var centers = result.Vertices;
var edges = result.Edges;
if (tris.Count > pts.Capacity)
{
{
pts.Capacity = tris.Count;
}
}
if (tris.Count > edges.Capacity)
{
edges.Capacity = tris.Count;
}
for (int ti = 0; ti < tris.Count; ti += 3)
{
var p0 = verts[tris[ti]];
var p1 = verts[tris[ti + 1]];
var p2 = verts[tris[ti + 2]];
// Triangle is in CCW order
Debug.Assert(Geom.ToTheLeft(p2, p0, p1));
centers.Add(Geom.CircumcircleCenter(p0, p1, p2));
}
for (int ti = 0; ti < tris.Count; ti += 3)
{
pts.Add(new PointTriangle(tris[ti], ti));
pts.Add(new PointTriangle(tris[ti + 1], ti));
pts.Add(new PointTriangle(tris[ti + 2], ti));
}
cmp.tris = tris;
cmp.verts = verts;
Profiler.BeginSample("Sorting");
pts.Sort(cmp);
Profiler.EndSample();
// The comparer lives on between runs of the algorithm, so clear the
// reference to the arrays so that the reference is lost. It may be
// the case that the calculator lives on much longer than the
// results, and not clearing these would keep the results alive,
// leaking memory.
cmp.tris = null;
cmp.verts = null;
for (int i = 0; i < pts.Count; i++)
{
result.FirstEdgeBySite.Add(edges.Count);
var start = i;
var end = -1;
for (int j = i + 1; j < pts.Count; j++)
{
if (pts[i].Point != pts[j].Point)
{
end = j - 1;
break;
}
}
if (end == -1)
{
end = pts.Count - 1;
}
i = end;
var count = end - start;
Debug.Assert(count >= 0);
for (int ptiCurr = start; ptiCurr <= end; ptiCurr++)
{
bool isEdge;
var ptiNext = ptiCurr + 1;
if (ptiNext > end)
{
ptiNext = start;
}
var ptCurr = pts[ptiCurr];
var ptNext = pts[ptiNext];
var tiCurr = ptCurr.Triangle;
var tiNext = ptNext.Triangle;
var p0 = verts[ptCurr.Point];
var v2nan = new Vector2(float.NaN, float.NaN);
if (count == 0)
{
isEdge = true;
}
else if (count == 1)
{
var cCurr = Geom.TriangleCentroid(verts[tris[tiCurr]], verts[tris[tiCurr + 1]], verts[tris[tiCurr + 2]]);
var cNext = Geom.TriangleCentroid(verts[tris[tiNext]], verts[tris[tiNext + 1]], verts[tris[tiNext + 2]]);
isEdge = Geom.ToTheLeft(cCurr, p0, cNext);
}
else
{
isEdge = !SharesEdge(tris, tiCurr, tiNext);
}
if (isEdge)
{
Vector2 v0, v1;
if (ptCurr.Point == tris[tiCurr])
{
v0 = verts[tris[tiCurr + 2]] - verts[tris[tiCurr + 0]];
}
else if (ptCurr.Point == tris[tiCurr + 1])
{
v0 = verts[tris[tiCurr + 0]] - verts[tris[tiCurr + 1]];
}
else
{
Debug.Assert(ptCurr.Point == tris[tiCurr + 2]);
v0 = verts[tris[tiCurr + 1]] - verts[tris[tiCurr + 2]];
}
if (ptNext.Point == tris[tiNext])
{
v1 = verts[tris[tiNext + 0]] - verts[tris[tiNext + 1]];
}
else if (ptNext.Point == tris[tiNext + 1])
{
v1 = verts[tris[tiNext + 1]] - verts[tris[tiNext + 2]];
}
else
{
Debug.Assert(ptNext.Point == tris[tiNext + 2]);
v1 = verts[tris[tiNext + 2]] - verts[tris[tiNext + 0]];
}
edges.Add(new VoronoiDiagram.Edge(
VoronoiDiagram.EdgeType.RayCCW,
ptCurr.Point,
tiCurr / 3,
-1,
Geom.RotateRightAngle(v0)
));
edges.Add(new VoronoiDiagram.Edge(
VoronoiDiagram.EdgeType.RayCW,
ptCurr.Point,
tiNext / 3,
-1,
Geom.RotateRightAngle(v1)
));
}
else
{
if (!Geom.AreCoincident(centers[tiCurr / 3], centers[tiNext / 3]))
{
edges.Add(new VoronoiDiagram.Edge(
VoronoiDiagram.EdgeType.Segment,
ptCurr.Point,
tiCurr / 3,
tiNext / 3,
v2nan
));
}
}
}
}
}
Vector2 Centroid(PointTriangle pt)
{
var ti = pt.Triangle;
return(Geom.TriangleCentroid(verts[tris[ti]], verts[tris[ti + 1]], verts[tris[ti + 2]]));
}