simple diffusion limited aggregation simulation with processing

simpleDLA.pde

int N = 2000;
float size = 5.0;
float r2 = size * size / 4.0;
PVector[] particles = new PVector[N];
boolean[] statuses = new boolean[N];

void setup() {
  float theta;
  float r;
  
  particles[0] = new PVector(0, 0);
  statuses[0] = true;
  for (int i = 1; i < N; i++) {
    theta = random(0, 2 * PI);
    r = random(40, 150);
    particles[i] = new PVector(r * cos(theta), r * sin(theta));
    statuses[i] = false;
  }

  size(500, 500);
  background(40, 90);
  translate(250, 250);
  noStroke();
}

void draw() {
  noStroke();
  fill(40, 90);
  rect(0, 0, 500, 500);
  translate(250, 250);
   
  for (int i = 0; i < N; i++) {
    PVector pos = particles[i];
    boolean isCluster = statuses[i];
    if (isCluster) {
      fill(40, 100, 200);
    } else {
      fill(255);
    }
    ellipse(pos.x, pos.y, size, size);
    if (isCluster) continue;
    
    float theta = random(0, 2 * PI);
    float r = size / 2;
    pos.add(new PVector(r * cos(theta), r * sin(theta)));
    
    for (int j = 0; j < N; j++) {
      if (j == i) continue;
      isCluster = statuses[j];
      if (!isCluster) continue;
      
      PVector otherPos = particles[j];
      float dist = (new PVector(pos.x - otherPos.x, pos.y - otherPos.y)).magSq();
      if (dist < r2 * 2.0 + 1) {
        statuses[i] = true;
        break;
      }
    }
  }
}

class は面倒だったので使わなかったです。