パーティクルでいろいろな形をつくる

/**
* morph by particles
*
* @author aa_debdeb
* @date 2016/08/19
*/

int state = 0;
ArrayList<Particle> particles;

void setup(){
  size(500, 500, P3D);
  particles = new ArrayList<Particle>();
  for(int i = 0; i < 5000; i++){
    particles.add(new Particle());
  }
}

void draw(){
  background(0);
  stroke(255, 0, 255);
  translate(width / 2, height / 2);
  rotateX(frameCount * 0.005);
  rotateY(frameCount * 0.010);
  rotateZ(frameCount * 0.015);
  for(Particle p: particles){
    p.display();
    p.update();
  } 
}

void mousePressed(){
  state += 1;
  if(state == 4){
    state = 0;
  }
  for(Particle p: particles){
    p.impact();
    p.setPos();
  }
}

class Particle{

  PVector pos, loc, vel;
  
  Particle(){
    float locSize = map(sqrt(random(1)), 0, 1, 0, 500);
    float locAng1 = random(PI);
    float locAng2 = random(TWO_PI);
    float x = locSize * sin(locAng1) * cos(locAng2);
    float y = locSize * cos(locAng1);
    float z = locSize * sin(locAng1) * sin(locAng2);
    loc = new PVector(x, y, z);
    impact();
    setPos();
  }
  
  void impact(){
    float velSize = random(5, 10);
    float velAng1 = random(PI);
    float velAng2 = random(TWO_PI);
    float vx = velSize * sin(velAng1) * cos(velAng2);
    float vy = velSize * cos(velAng1);
    float vz = velSize * sin(velAng1) * sin(velAng2);
    vel = new PVector(vx, vy, vz);
  }
  
  void setPos(){
    float posSize, px, py, pz;
    switch(state){
      case 0: // sphere
        posSize = 100;
        float posAng1 = random(PI);
        float posAng2 = random(TWO_PI);
        px = posSize * sin(posAng1) * cos(posAng2);
        py = posSize * cos(posAng1);
        pz = posSize * sin(posAng1) * sin(posAng2);
        pos = new PVector(px, py, pz);
        break;
      case 1: // cube
        float r = random(1);
        float e = 70;
        if(r < 0.33){
          px = random(1) < 0.5 ? e: -e;
          py = random(-e, e);
          pz = random(-e, e);
        } else if(r < 0.66){
          px = random(-e, e);
          py = random(1) < 0.5 ? e: -e;
          pz = random(-e, e);       
        } else {
          px = random(-e, e);
          py = random(-e, e);
          pz = random(1) < 0.5 ? e: -e;
        }
        pos = new PVector(px, py, pz);
        break;
      case 2: // rectangle
        px = random(-70, 70);
        py = random(-70, 70);
        pz = 0;
        pos = new PVector(px, py, pz);
        break;
      case 3:
        posSize = map(sqrt(random(1)), 0, 1, 0, 100);
        float posAng = random(TWO_PI);
        px = posSize * cos(posAng);
        py = posSize * sin(posAng);
        pz = 0;
        pos = new PVector(px, py, pz);
        break;
    }
  }
  
  void display(){
    point(loc.x, loc.y, loc.z);
  }
  
  void update(){
    PVector acc = PVector.sub(pos, loc);
    acc.limit(0.1);
    vel.add(acc);
    vel.mult(0.98);
    loc.add(vel);
  }
  
}