/// <summary>
/// http://alienryderflex.com/polygon_fill/
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="polygon"></param>
/// <param name="fillVolume"></param>
/// <param name="dimX"></param>
/// <param name="dimY"></param>
/// <param name="dimZ"></param>
/// <param name="sliceZ"></param>
/// <param name="fillValue"></param>
/// <returns></returns>
private static VoxelCounts FillPolygonAndCount(
PointF[] polygon,
ushort[] fillVolume,
ushort fillValue,
Volume2D <byte> countVolume,
byte foregroundId)
{
var bounds = GetBoundingBox(polygon);
const float epsilon = 0.01f;
var length = polygon.Length;
var nodeIntersections = new IntersectionXPoint[length * 2];
var nodeX = new float[length];
var polygonX = new float[length];
var polygonY = new float[length];
for (var index = 0; index < length; index++)
{
var point = polygon[index];
polygonX[index] = point.X;
polygonY[index] = point.Y;
}
var voxelCounts = new VoxelCounts();
// Loop through the rows of the image.
for (int y = 0; y < countVolume.DimY; y++)
{
float yPlusEpsilon = y + epsilon;
float yMinusEpsilon = y - epsilon;
if ((yPlusEpsilon < bounds.Top && yMinusEpsilon < bounds.Top) ||
(yPlusEpsilon > bounds.Bottom && yMinusEpsilon > bounds.Bottom))
{
continue;
}
// Build a list of nodes, sorted
int nodesBoth = FindIntersections(polygonX, polygonY, nodeIntersections, y, yPlusEpsilon, yMinusEpsilon);
// Merge
int nodes = MergeIntersections(nodeIntersections, nodeX, nodesBoth);
// Fill the pixels between node pairs.
voxelCounts += FillNodePairsAndCount(
fillVolume,
fillValue,
epsilon,
nodeX,
y,
nodes,
countVolume,
foregroundId);
}
return(voxelCounts);
}
/// <summary>
/// Fills all points that fall inside of a given polygon, and at the same time,
/// aggregate statistics on what values are present at the filled pixel
/// positions in a "count volume" that has the same size as the fill volume.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <typeparam name="U"></typeparam>
/// <param name="polygon"></param>
/// <param name="fillVolume"></param>
/// <param name="dimX"></param>
/// <param name="dimY"></param>
/// <param name="dimZ"></param>
/// <param name="sliceZ"></param>
/// <param name="fillValue"></param>
/// <param name="countVolume"></param>
/// <param name="foregroundId"></param>
/// <returns></returns>
public static VoxelCounts FillPolygonAndCount(
PointInt[] polygon,
ushort[] fillVolume,
ushort fillValue,
Volume2D <byte> countVolume,
byte foregroundId)
{
polygon = polygon ?? throw new ArgumentNullException(nameof(polygon));
fillVolume = fillVolume ?? throw new ArgumentNullException(nameof(fillVolume));
countVolume = countVolume ?? throw new ArgumentNullException(nameof(countVolume));
if (polygon.Length == 0)
{
throw new ArgumentOutOfRangeException(nameof(polygon), "The polygon does not contain any points.");
}
if (fillVolume.Length != countVolume.Length)
{
throw new ArgumentException("The fill and the count volume must have the same size.", nameof(fillVolume));
}
var pointsAsFloat = polygon.Select(point => new PointF(point.X, point.Y)).ToArray();
uint foregroundCount = 0;
uint otherCount = 0;
var countArray = countVolume.Array;
var dimX = countVolume.DimX;
foreach (var point in polygon)
{
// Manually computing index, rather than relying on GetIndex, brings substantial speedup.
var index = point.X + dimX * point.Y;
if (fillVolume[index] != fillValue)
{
fillVolume[index] = fillValue;
if (countArray[index] == foregroundId)
{
foregroundCount++;
}
else
{
otherCount++;
}
}
}
var voxelCountsAtPoints = new VoxelCounts(foregroundCount, otherCount);
var voxelCountsInside = FillPolygonAndCount(
pointsAsFloat,
fillVolume,
fillValue,
countVolume,
foregroundId);
return(voxelCountsAtPoints + voxelCountsInside);
}
/// <summary>
/// Creates a new instance of the class.
/// </summary>
/// <param name="points"></param>
/// <param name="voxelCounts"></param>
/// <param name="insideOfPolygon"></param>
/// <param name="isBackground"></param>
/// <param name="startPointMinimumY"></param>
public PolygonPoints(
PointInt[] points,
VoxelCounts voxelCounts,
ushort insideOfPolygon,
bool isInside,
PointInt startPointMinimumY)
{
Points = points ?? throw new ArgumentNullException(nameof(points));
VoxelCounts = voxelCounts ?? throw new ArgumentNullException(nameof(voxelCounts));
InsideOfPolygon = insideOfPolygon;
IsInnerContour = isInside;
StartPointMinimumY = startPointMinimumY;
}
