attraction and gravitation

sketch205572
xxxxxxxxxx
 
int num = 20;
Mover[ ]movers = new Mover[num];
Attractor a, a2;
float theta;
​
void setup() {
  size(800, 600);
  background(#3F2143);
  for (int i=0; i<movers.length; i++) {
    movers[i] = new Mover(random(0.5, 2), random(width), random(height));
  }
  a = new Attractor();
  a2 = new Attractor();
}
​
void draw() {
  //background(#490A3D);
​
  //a.display();
  //a2.display();
​
  for (int i=0; i<movers.length; i++) {
    PVector f1 = a.attract(movers[i]);
    PVector f2 = a2.attract(movers[i]);
    PVector f = PVector.add(f1, f2);
    movers[i].applyForce(f);
    movers[i].update();
    movers[i].display();
    movers[i].drawLines();
    //movers[i].checkEdges();
  }
  theta += 0.01;
  //if (frameCount%3==0 && frameCount<600) saveFrame("image-###.gif");
}
​
void keyPressed() {
  save(random(12344) + ".png");
}
​
class Attractor {
​
  float mass;
  PVector location;
  float G;
​
  Attractor() {
    location = new PVector(random(width), random(height));
    mass = 20;
    G = 1;
  }
​
  void display() {
    stroke(#ffffff);
    strokeWeight(7);
    fill(#ffffff,20);
    noStroke();
    float mov = map(sin(theta),-1,1,-150,150);
    mov = 0;
    ellipse(location.x+mov, location.y+mov, mass*2, mass*2);
  }
​
  PVector attract(Mover m) {
    PVector force = PVector.sub(location, m.location);
    float distance = force.mag();
    distance = constrain(distance, 5.0, 50.0);
    force.normalize();
    float strength = (G*mass*m.mass)/(distance*distance);
    force.mult(strength);
​
    return force;
  }
}
​
class Mover {
​
  PVector location, velocity, acceleration;
  float sz, mass;
​
  Mover(float m, float x, float y) {
    location = new PVector(x, y);
    velocity = new PVector(random(-4, 4), random(-4, 4));
    acceleration = new PVector(0, 0);
    mass = m;
    sz = mass*16;
    sz =2;
  }
​
  void update() {
    velocity.add(acceleration);
    location.add(velocity);
​
    acceleration.mult(0);
  }
​
  void display() {
    fill(255, 50);
    stroke(#ffffff);
    noStroke();
    strokeWeight(2);
    ellipse(location.x, location.y, sz, sz);
  }
​
  void applyForce(PVector force) {
    PVector f = PVector.div(force, mass);
    acceleration.add(f);
  }
​
  void drawLines() {
    for (int i=0; i<movers.length; i++) {
      Mover o = movers[i];
      float distance = dist(location.x, location.y, o.location.x, o.location.y);
      stroke(255, 10);
      if (distance>0 && distance<100) line(location.x, location.y, o.location.x, o.location.y);
    }
  }
​
  void checkEdges() {
    if (location.x > width-sz/2 || location.x < sz/2) velocity.x *= -1;
    if (location.y > height-sz/2 || location.y < sz/2) velocity.y *= -1;
  }
}