103 lines
2.9 KiB
C#
103 lines
2.9 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Linq;
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using Assets.Common;
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using UnityEngine;
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namespace Assets.PointDistribution
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{
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public class PoissonDiskSampler : IPointDistribution
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{
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public System.Random Generator { get; set; } = new System.Random();
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private int k;
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private double r;
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private double Random(double max, double min = 0)
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{
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return Generator.NextDouble() * (max - min) + min;
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}
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public PoissonDiskSampler(double r, int k = 30)
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{
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this.k = k;
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this.r = r;
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}
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public IEnumerable<Point> Generate(double width, double height)
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{
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var size = r / Mathf.Sqrt(2);
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var grid = new Dictionary<(int, int), Point>();
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var active = new List<Point>();
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var initial = new Point(Random(width), Random(height));
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void AddToGrid(Point point)
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{
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grid.Add(
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((int)Math.Floor(point.x / size), (int)Math.Floor(point.y / size)),
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point
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);
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active.Add(point);
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}
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bool IsPointOk(Point point)
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{
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if (point.x < 0 || point.y < 0 || point.x > width || point.y > height)
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{
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return false;
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}
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var x = (int)Math.Floor(point.x / size);
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var y = (int)Math.Floor(point.y / size);
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var neighbours = new List<(int, int)> {
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(x - 1, y + 1), (x, y + 1), (x + 1, y + 1),
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(x - 1, y), (x, y), (x + 1, y),
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(x - 1, y - 1), (x, y - 1), (x + 1, y - 1)
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};
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return neighbours
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.Where(p => grid.ContainsKey(p))
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.All(p => Point.Dist(point, grid[p]) > r);
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}
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Point RandomPoint(Point origin)
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{
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var angle = Random(Mathf.PI * 2);
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var length = Random(2 * r, r);
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return origin + new Point(Math.Sin(angle), Math.Cos(angle)) * length;
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}
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AddToGrid(initial);
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yield return initial;
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int watchdog = 3000000;
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while (active.Count > 0 && watchdog-- > 0)
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{
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var current = (int)Math.Floor(Random(active.Count));
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var point = active[current];
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var i = 0;
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for (; i < k; i++)
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{
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var candidate = RandomPoint(point);
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if (IsPointOk(candidate))
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{
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AddToGrid(candidate);
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yield return candidate;
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break;
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}
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}
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if (i >= k)
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active.RemoveAt(current);
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}
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}
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}
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} |