private static bool IsValid2D(Vector3D candidate, double radius, int searchZone, Vector3D sampleRegionSize, double cellSize, int[,] grid, List <PoissonDisc> points)
{
if (candidate.X >= 0 && candidate.X < sampleRegionSize.X && candidate.Y >= 0 && candidate.Y < sampleRegionSize.Y)
{
int cellX = (int)(candidate.X / cellSize);
int cellY = (int)(candidate.Y / cellSize);
int searchStartX = Math.Max(0, cellX - searchZone);
int searchEndX = Math.Min(cellX + searchZone, grid.GetLength(0) - 1);
int searchStartY = Math.Max(0, cellY - searchZone);
int searchEndY = Math.Min(cellY + searchZone, grid.GetLength(1) - 1);
for (int x = searchStartX; x <= searchEndX; x++)
{
for (int y = searchStartY; y <= searchEndY; y++)
{
int pointIndex = grid[x, y] - 1;
if (pointIndex != -1)
{
PoissonDisc disc = points[pointIndex];
double sqrDst = (candidate - disc.position).SqrMagnitude;
double r = disc.radius + radius;
if (sqrDst < r * r)
{
return(false);
}
}
}
}
return(true);
}
return(false);
}
private static List <PoissonDisc> CreateNeighbourList3D(List <PoissonDisc> points, int[,,] grid, int searchZone)
{
List <PoissonDisc> newPoints = new List <PoissonDisc>();
for (int x = 0; x < grid.GetLength(0); x++)
{
for (int y = 0; y < grid.GetLength(1); y++)
{
for (int z = 0; z < grid.GetLength(2); z++)
{
int pointIndex = grid[x, y, z] - 1;
if (pointIndex != -1)
{
PoissonDisc disc = points[pointIndex];
newPoints.Add(disc);
int searchStartX = Math.Max(0, x - searchZone);
int searchEndX = Math.Min(x + searchZone, grid.GetLength(0) - 1);
int searchStartY = Math.Max(0, y - searchZone);
int searchEndY = Math.Min(y + searchZone, grid.GetLength(1) - 1);
int searchStartZ = Math.Max(0, z - searchZone);
int searchEndZ = Math.Min(z + searchZone, grid.GetLength(2) - 1);
for (int x1 = searchStartX; x1 <= searchEndX; x1++)
{
for (int y1 = searchStartY; y1 <= searchEndY; y1++)
{
for (int z1 = searchStartZ; z1 <= searchEndZ; z1++)
{
int pointIndex2 = grid[x1, y1, z1] - 1;
if (pointIndex2 != -1 && pointIndex2 != pointIndex)
{
PoissonDisc disc2 = points[pointIndex2];
double sqrDst = (disc2.position - disc.position).SqrMagnitude;
if (sqrDst < disc.radiusSquared * 2)
{
disc.AddNeighbour(disc2);
}
}
}
}
}
}
}
}
}
return(newPoints);
}
public void AddNeighbour(PoissonDisc neighbour)
{
neighbours.Add(neighbour);
}
public static List <PoissonDisc> Sample2D(uint seed, double minRadius, Vector3D regionSize, int k = 4, bool createNeighbours = false, Vector3D centerPos = null, Func <Vector3D, float> calcRadius = null)
{
List <PoissonDisc> points = new List <PoissonDisc>();
double maxRadius = 0f;
int searchZone = 2;
RandomHash hash = new RandomHash(seed);
double cellSize = minRadius * 2 / 1.41421356237; // Minimum distance between cells divided by sqrt(2)
int[,] grid = new int[(int)Math.Ceiling(regionSize.X / cellSize), (int)Math.Ceiling(regionSize.Y / cellSize)];
List <PoissonDisc> spawnPoints = new List <PoissonDisc>
{
new PoissonDisc(centerPos ?? regionSize / 2, minRadius)
};
points.Add(spawnPoints[0]);
grid[(int)(spawnPoints[0].position.X / cellSize), (int)(spawnPoints[0].position.Y / cellSize)] = points.Count;
int currVal = 0;
while (spawnPoints.Count > 0)
{
int spawnIndex = hash.Next(0, spawnPoints.Count, ++currVal);
PoissonDisc spawnCentre = spawnPoints[spawnIndex];
bool candidateAccepted = false;
double randRot = hash.NextDouble(0, 1, currVal);
double nextRadius = calcRadius == null ? minRadius : calcRadius(spawnCentre.position);
double distance = spawnCentre.radius + nextRadius;
double r = distance + 0.0000001;
for (int j = 0; j < k; j++)
{
double theta = pi * (randRot + 1.0 * j / k);
double x = spawnCentre.position.X + r * Math.Cos(theta);
double y = spawnCentre.position.Y + r * Math.Sin(theta);
Vector3D candidate = new Vector3D(x, y, 0);
if (IsValid2D(candidate, nextRadius, searchZone, regionSize, cellSize, grid, points))
{
if (distance > maxRadius)
{
maxRadius = distance;
searchZone = (int)Math.Ceiling(distance / cellSize);
}
PoissonDisc disc = new PoissonDisc(candidate, nextRadius);
points.Add(disc);
spawnPoints.Add(disc);
grid[(int)(candidate.X / cellSize), (int)(candidate.Y / cellSize)] = points.Count;
candidateAccepted = true;
break;
}
}
if (!candidateAccepted)
{
spawnPoints.RemoveAt(spawnIndex);
}
}
if (createNeighbours)
{
return(CreateNeighbourList2D(points, grid, searchZone));
}
return(points);
}
