private void Init()
{
// Reuse memory buffers of 'intersections' and 'activeEdges' for key-value sorting,
// since that region is unused at initialization time.
Span <float> keys0 = this.intersections.Slice(0, this.sorted0.Length);
Span <float> keys1 = MemoryMarshal.Cast <int, float>(this.activeEdges.Buffer);
for (int i = 0; i < this.edges.Length; i++)
{
ref ScanEdge edge = ref this.edges[i];
keys0[i] = edge.Y0;
keys1[i] = edge.Y1;
this.sorted0[i] = i;
this.sorted1[i] = i;
}
public Span <float> ScanOddEven(float y, Span <ScanEdge> edges, Span <float> intersections)
{
DebugGuard.MustBeLessThanOrEqualTo(edges.Length, MaxEdges, "edges.Length");
int intersectionCounter = 0;
int offset = 0;
Span <int> active = this.ActiveEdges;
for (int i = 0; i < active.Length; i++)
{
int flaggedIdx = active[i];
int edgeIdx = Strip(flaggedIdx);
ref ScanEdge edge = ref edges[edgeIdx];
float x = edge.GetX(y);
if (IsEntering(flaggedIdx))
{
Emit(x, edge.EmitV0, intersections, ref intersectionCounter);
}
else if (IsLeaving(flaggedIdx))
{
Emit(x, edge.EmitV1, intersections, ref intersectionCounter);
offset++;
// Do not offset:
continue;
}
else
{
// Emit once:
intersections[intersectionCounter++] = x;
}
// Unmask and offset:
active[i - offset] = edgeIdx;
}