Help a newbie with polymorphic particles

Processing Coding Questions
5

Hi jb4x,

I have spent a couple of hours trying to work out where I am going wrong here. I have pasted my code below, in what respect am i not following your pointers? I understand the theory of what you have written above, but am stuggling to put it into practice!

int numBalls = 4;
Ball[] balls = new Ball[numBalls];

int numBlips = 15;
Blip[] blips = new Blip[numBlips];

float spring = 1.6;
float gravity = 0.001;
float friction = -0.8;

void setup() {
  frameRate(80);

  size(displayWidth, displayHeight, OPENGL, P2D);


  for (int i = 0; i < numBalls; i++) 
    balls[i] = new Ball(random(300, 600), random(450, 650), (80), i, balls);

  for (int a = 0; a < numBlips; a++) 
    blips[a] = new Blip(random(300, 600), random(450, 650), (10), a, blips);

  smooth();
}

int index = 0;

void draw() {
  background(0, 10);

  for (Ball ball : balls) {
    ball.collide();
    ball.move();
    ball.display();
  }

  for (Blip blip : blips) {
    blip.collide();
    blip.move();
    blip.display();
  }

  for (int i = 0; i < numBalls; i++) {
    for (int j = i; j < numBalls; j++) {
      Balls[i].collide(Balls[j]);
    }

    for (int j = 0; j < numBlips; j++) {
      Balls[i].collide(Blip[j]);
    }
  }
}
class Ball {

  float x, y;
  float diameter;
  float vx = 0;
  float vy = 0;
  int id;
  Ball[] other;


  Ball(float xin, float yin, float din, int idin, Ball[] oin) {
    x = xin;
    y = yin;
    diameter = din;
    id = idin;
    other = oin;
  }    

  void collide() {
    for (int i = id + 1; i < numBalls; i++) {
      float dx = other[i].x - x;
      float dy = other[i].y - y;
      float distance = sqrt(dx*dx + dy*dy);
      float minDist = other[i].diameter/2 + diameter/2;
      if (distance < minDist) { 
        float angle = atan2(dy, dx);
        float targetX = x + cos(angle) * minDist;
        float targetY = y + sin(angle) * minDist;
        float ax = (targetX - other[i].x) * spring*1.1;
        float ay = (targetY - other[i].y) * spring*1.1;
        vx -= ax;
        vy -= ay;
        other[i].vx += ax;
        other[i].vy += ay;
      }
      collideWith(blip other);
    }
  }
  void move() {
    vy += gravity;
    x += vx;
    y += vy;
    if (x + diameter/2 > width) {
      x = width - diameter/2;
      vx *= friction;
      //sound[index].trigger();
    } else if (x - diameter/2 < 0) {
      x = diameter/2;
      vx *= friction;
    }
    if (y + diameter/2 > height) {
      y = height - diameter/2;
      vy *= friction;

      ;
    } else if (y - diameter/2 < 0) {
      y = diameter/2;
      vy *= friction;

      ;
    }
  }

  void display() {
    float disc=40; 
    gradientdisc( 
      x, 
      y, 
      40, 
      disc, 
      color(0, 0, 255), 
      color(255, 255, 255) 
      ); 
    noStroke();
  }
  void gradientdisc( float x, float y, float radiusX, float radiusY, int fromC, int toC )
  { 
    noStroke(); 
    beginShape(TRIANGLE_STRIP);
    int halfC = lerpColor(fromC, toC, 0.4);

    for (float theta=0; theta<TWO_PI; theta+=TWO_PI/36)
    { 
      fill(halfC);  
      vertex(x, y);
      if ( theta <= PI )
        fill(lerpColor(fromC, toC, (theta%PI)/PI ));
      else
        fill(lerpColor(toC, fromC, (theta%PI)/PI ));
      vertex(x+radiusX*cos(theta), y+radiusY*sin(theta));
    } 
    endShape();
    float disc2=50; 
    stroke(0, 10);
    strokeWeight(1);
    noFill();
    ellipse(x, y, 100, disc2*2);
  }
}

class Blip {

  float x, y;
  float diameter;
  float vx = 0;
  float vy = 0;
  int id;
  Blip[] other;

  Blip(float xin, float yin, float din, int idin, Blip[] oin) {
    x = xin;
    y = yin;
    diameter = din;
    id = idin;
    other = oin;
  } 

  void collide() {
    for (int i = id + 1; i < numBlips; i++) {
      float dx = other[i].x - x;
      float dy = other[i].y - y;
      float distance = sqrt(dx*dx + dy*dy);
      float minDist = other[i].diameter/2 + diameter/2;
      if (distance < minDist) { 
        float angle = atan2(dy, dx);
        float targetX = x + cos(angle) * minDist;
        float targetY = y + sin(angle) * minDist;
        float ax = (targetX - other[i].x) * spring * 1.2;
        float ay = (targetY - other[i].y) * spring * 1.2;
        vx -= ax;
        vy -= ay;
        other[i].vx += ax;
        other[i].vy += ay;
      }
      collideWith(ball other);
    }
  }
  void move() {
    vy += gravity * 2;
    x += vx;
    y += vy;
    if (x + diameter/2 > width) {
      x = width - diameter/2;
      vx *= friction;
    } else if (x - diameter/2 < 0) {
      x = diameter/2;
      vx *= friction;
    }
    if (y + diameter/2 > height) {
      y = height - diameter/2;
      vy *= friction;
    } else if (y - diameter/2 < 0) {
      y = diameter/2;
      vy *= friction;
    }
  }

  void display() {
    stroke(255, 0, 144);
    strokeWeight(1);
    noFill();
    ellipse(x, y, diameter, diameter);
  }
}```