let x=20;
let y=30;
let d=50;
let speed1 = 5;
let speed2 = 8;
function setup(){
createCanvas(600,600);
}
function draw(){
background(120);
x+=speed1;
fill(random(255));
if((x>width-d/2)||(x<d/2)){
speed1=-speed1;
}
y-=speed2;
if((y>599)||(y<d/2)){
speed2=-speed2;
}
ellipse(x,y,d,d);
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.1.9/p5.min.js"></script>