suqash_bounce.pde

// world parameters
float startForce = 2.5;
float gravity = 1;
float squash = 0.2;
float r = 50; // ball radius

PVector p;
PVector g;
PVector ball;
PVector f;

void setup(){
  frameRate(30);
  size(1000, 500);
  
  g = new PVector(0, gravity);
  p = new PVector(0,0);
  ball = new PVector(r,r);
  
  f = new PVector(0,0);
  f.add(new PVector(startForce, 0));
}

void update(){
  f.add(g);
    
  if(p.y >= (height-r/2)){
    f.y = -f.y*(1 - squash);
    ball.x = ball.x * (1+squash);
    ball.y = ball.y * (1-squash);
  } else {
    ball.x = r;
    ball.y = r;
  }
  
  p.add(f);
}


void draw(){
  update();
  
  background(255);
  fill(0);
  noStroke();
  ellipse(p.x, p.y, ball.x, ball.y);
}