public static ScanEdgeCollection Create(
IPath polygon,
MemoryAllocator allocator,
int subsampling)
{
TessellatedMultipolygon multipolygon = TessellatedMultipolygon.Create(polygon, allocator);
return(Create(multipolygon, allocator, subsampling));
}
public void Create_FromStar()
{
var polygon = new Star(100, 100, 5, 30, 60);
PointF[] points = polygon.Flatten().Single().Points.Span.ToArray();
using var multipolygon = TessellatedMultipolygon.Create(polygon, MemoryAllocator);
VerifyRing(multipolygon[0], points, true, false);
}
public void Create_FromRecangle()
{
var polygon = new RectangularPolygon(10, 20, 100, 50);
PointF[] points = polygon.Flatten().Single().Points.Span.ToArray();
using var multipolygon = TessellatedMultipolygon.Create(polygon, MemoryAllocator);
VerifyRing(multipolygon[0], points, true, false);
Assert.Equal(4, multipolygon.TotalVertexCount);
}
public void Create_FromPolygon_Case2(bool reverseOriginal)
{
PointF[] points = PolygonFactory.CreatePointArray((0, 0), (2, 0), (3, 1), (3, 0), (6, 0), (6, 2), (5, 2), (5, 1), (4, 1), (4, 2), (2, 2), (1, 1), (0, 2));
if (reverseOriginal)
{
points.AsSpan().Reverse();
}
var polygon = new Polygon(new LinearLineSegment(points));
using var multipolygon = TessellatedMultipolygon.Create(polygon, MemoryAllocator);
VerifyRing(multipolygon[0], points, !reverseOriginal, false);
}
public void Create_FromPolygon_Case1(bool reverseOriginal)
{
PointF[] points = PolygonFactory.CreatePointArray((0, 3), (3, 3), (3, 0), (1, 2), (1, 1), (0, 0));
if (reverseOriginal)
{
points.AsSpan().Reverse();
}
var polygon = new Polygon(new LinearLineSegment(points));
using var multipolygon = TessellatedMultipolygon.Create(polygon, MemoryAllocator);
VerifyRing(multipolygon[0], points, reverseOriginal, false);
Assert.Equal(6, multipolygon.TotalVertexCount);
}
public static PolygonScanner Create(
IPath polygon,
int minY,
int maxY,
int subsampling,
IntersectionRule intersectionRule,
MemoryAllocator allocator)
{
var multipolygon = TessellatedMultipolygon.Create(polygon, allocator);
var edges = ScanEdgeCollection.Create(multipolygon, allocator, subsampling);
var scanner = new PolygonScanner(edges, multipolygon.TotalVertexCount * 2, minY, maxY, subsampling, intersectionRule, allocator);
scanner.Init();
return(scanner);
}
internal static ScanEdgeCollection Create(TessellatedMultipolygon multipolygon, MemoryAllocator allocator, int subsampling)
{
// We allocate more than we need, since we don't know how many horizontal edges do we have:
IMemoryOwner <ScanEdge> buffer = allocator.Allocate <ScanEdge>(multipolygon.TotalVertexCount);
RingWalker walker = new RingWalker(buffer.Memory.Span);
using IMemoryOwner <float> roundedYBuffer = allocator.Allocate <float>(multipolygon.Max(r => r.Vertices.Length));
Span <float> roundedY = roundedYBuffer.Memory.Span;
foreach (TessellatedMultipolygon.Ring ring in multipolygon)
{
if (ring.VertexCount < 3)
{
continue;
}
ReadOnlySpan <PointF> vertices = ring.Vertices;
RoundY(vertices, roundedY, subsampling);
walker.PreviousEdge = new EdgeData(vertices, roundedY, vertices.Length - 2); // Last edge
walker.CurrentEdge = new EdgeData(vertices, roundedY, 0); // First edge
walker.NextEdge = new EdgeData(vertices, roundedY, 1); // Second edge
walker.Move(false);
for (int i = 1; i < vertices.Length - 2; i++)
{
walker.NextEdge = new EdgeData(vertices, roundedY, i + 1);
walker.Move(true);
}
walker.NextEdge = new EdgeData(vertices, roundedY, 0); // First edge
walker.Move(true); // Emit edge before last edge
walker.NextEdge = new EdgeData(vertices, roundedY, 1); // Second edge
walker.Move(true); // Emit last edge
}
