endogenous

//caused by factors inside the system

​

let r=50, x=50, y=50, vx=0.5, vy=1;

​

function setup() {

  createCanvas(windowWidth, windowHeight);

  frameRate(20);

  noStroke();

}

function mousePressed(){

  y = 50, vy = 9;

}

function draw() {

  background(100);

  ellipse(x, y, r);

  x = x + vx;

  y = y + vy;

  //vy += 1;

  if (y > height-r/2){

    vy = -vy // * 0.95;

    y = height-r/2;

  }

  if (x > width-r/2){

    vx = -vx;

    x = width-r/2;

  }

  if (x < 0+r/2){

    vx = -vx;

    x = r/2;

  }

  if (y < 0+r/2){

    vy = -vy // * 0.95;

    y = r/2;

  }

}