xevion/procedural-placement
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implement poisson sampling

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Xevion
2020-05-05 20:38:24 -05:00
parent ff0fb7521a
commit 1051fd3fde
2 changed files with 59 additions and 6 deletions
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61
procedural-placement/Assets/PointGeneration.cs
View File

@@ -1,23 +1,26 @@
using System.Collections.Generic;
using NUnit.Framework.Constraints;
using UnityEngine;
public static class PointGeneration {
public static List<Vector2> random_sampling(int numPoints, Vector2 regionSize) {
// Create a new empty list of points, and add some randomly
var points = new List<Vector2>();
List<Vector2> points = new List<Vector2>();
for (var i = 0; i < numPoints; i++) {
points.Add(
new Vector2(
Random.Range(-regionSize.x, regionSize.x),
Random.Range(-regionSize.y, regionSize.y)));
Random.Range(0, regionSize.x * 2),
Random.Range(0, regionSize.y * 2)
));
}
return points;
}
public static List<Vector2> poisson_sampling(int numPoints, Vector2 regionSize, int radius) {
public static List<Vector2> poisson_sampling(int numPoints, Vector2 regionSize, int radius, int attempts = 30) {
float cellSize = radius / Mathf.Sqrt(2);
// A grid for
int[,] grid = new int[Mathf.CeilToInt(regionSize.x / cellSize), Mathf.CeilToInt(regionSize.y / cellSize)];
List<Vector2> points = new List<Vector2>();
List<Vector2> spawnPoints = new List<Vector2>();
@@ -26,8 +29,58 @@ public static class PointGeneration {
while (spawnPoints.Count > 0) {
int spawnIndex = Random.Range(0, spawnPoints.Count);
Vector2 spawnCenter = spawnPoints[spawnIndex];
bool candidateAccepted = false;
for (int i = 0; i < attempts; i++) {
float angle = Random.value * Mathf.PI * 2; // Random radian angle
Vector2 dir = new Vector2(Mathf.Sin(angle), Mathf.Cos(angle));
Vector2 candidate = spawnCenter + dir * Random.Range(radius, radius * 2);
if (poisson_valid(candidate, regionSize, cellSize, points, grid, radius)) {
points.Add(candidate);
spawnPoints.Add(candidate);
grid[(int) (candidate.x / cellSize), (int) (candidate.y / cellSize)] = points.Count;
candidateAccepted = true;
break;
}
}
if (!candidateAccepted) {
spawnPoints.RemoveAt(spawnIndex);
}
}
return points;
}
private static bool IsValidPoint(Vector2 point, Vector2 region) {
return point.x >= 0 && point.y >= 0 && point.x < region.x && point.y < region.y;
}
private static bool poisson_valid(Vector2 candidate, Vector2 regionSize, float cellSize, List<Vector2> points,
int[,] grid, float radius) {
// Check that the point is valid
if (!IsValidPoint(candidate, regionSize))
return false;
int cellX = (int) (candidate.x / cellSize);
int cellY = (int) (candidate.y / cellSize);
int searchStartX = Mathf.Max(0, cellX - 2);
int searchEndX = Mathf.Min(cellX + 2, grid.GetLength(0) - 1);
int searchStartY = Mathf.Max(0, cellY - 2);
int searchEndY = Mathf.Min(cellY + 2, 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) continue;
float sqrDst = (candidate - points[pointIndex]).sqrMagnitude;
if (sqrDst < radius * radius) {
return false;
}
}
}
return true;
}
}

2
procedural-placement/Assets/PointRendering.cs
View File

@@ -41,7 +41,7 @@ public class PointRendering : MonoBehaviour {
_points = PointGeneration.random_sampling(numPoints, regionSize);
break;
case SamplingTypes.Poisson:
_points = new List<Vector2>();
_points = PointGeneration.poisson_sampling(numPoints, regionSize, 1, 30);
break;
default:
throw new ArgumentOutOfRangeException();