public static Image PartitionMask(Image mask, float3[] centroids)
{
float[] MaskData = mask.GetHostContinuousCopy();
int[] Partitions = new int[MaskData.Length];
int3 Dims = mask.Dims;
Parallel.For(0, Dims.Z, z =>
{
for (int y = 0; y < Dims.Y; y++)
{
for (int x = 0; x < Dims.X; x++)
{
if (MaskData[Dims.ElementFromPosition(x, y, z)] != 1)
{
Partitions[Dims.ElementFromPosition(x, y, z)] = -1;
}
else
{
float3 Pos = new float3(x, y, z);
float BestDist = float.MaxValue;
int BestCentroid = 0;
for (int c = 0; c < centroids.Length; c++)
{
float Dist = (Pos - centroids[c]).LengthSq();
if (Dist < BestDist)
{
BestDist = Dist;
BestCentroid = c;
}
}
Partitions[Dims.ElementFromPosition(x, y, z)] = BestCentroid;
}
}
}
});
return(new Image(Partitions.Select(v => (float)v).ToArray(), Dims));
}
public static float3[] FillWithEquidistantPoints(Image mask, int n, out float R)
{
float3 MaskCenter = mask.AsCenterOfMass();
float[] MaskData = mask.GetHostContinuousCopy();
int3 Dims = mask.Dims;
float3[] BestSolution = null;
float a = 0, b = Dims.X / 2;
R = (a + b) / 2;
float3 Offset = new float3(0, 0, 0);
for (int o = 0; o < 2; o++)
{
for (int i = 0; i < 10; i++)
{
R = (a + b) / 2;
float Root3 = (float)Math.Sqrt(3);
float ZTerm = (float)(2 * Math.Sqrt(6) / 3);
float SpacingX = R * 2;
float SpacingY = Root3 * R;
float SpacingZ = ZTerm * R;
int3 DimsSphere = new int3(Math.Min(512, (int)Math.Ceiling(Dims.X / SpacingX)),
Math.Min(512, (int)Math.Ceiling(Dims.Y / SpacingX)),
Math.Min(512, (int)Math.Ceiling(Dims.Z / SpacingX)));
BestSolution = new float3[DimsSphere.Elements()];
for (int z = 0; z < DimsSphere.Z; z++)
{
for (int y = 0; y < DimsSphere.Y; y++)
{
for (int x = 0; x < DimsSphere.X; x++)
{
BestSolution[DimsSphere.ElementFromPosition(x, y, z)] = new float3(2 * x + (y + z) % 2,
Root3 * (y + 1 / 3f * (z % 2)),
ZTerm * z) * R + Offset;
}
}
}
List <float3> InsideMask = BestSolution.Where(p =>
{
int3 ip = new int3(p);
if (ip.X >= 0 && ip.X < Dims.X && ip.Y >= 0 && ip.Y < Dims.Y && ip.Z >= 0 && ip.Z < Dims.Z)
{
return(MaskData[Dims.ElementFromPosition(new int3(p))] == 1);
}
return(false);
}).ToList();
BestSolution = InsideMask.ToArray();
if (BestSolution.Length == n)
{
break;
}
else if (BestSolution.Length < n)
{
b = R;
}
else
{
a = R;
}
}
float3 CenterOfPoints = MathHelper.Mean(BestSolution);
Offset = MaskCenter - CenterOfPoints;
a = 0.8f * R;
b = 1.2f * R;
}
BestSolution = BestSolution.Select(v => v + Offset).ToArray();
return(BestSolution);
}