SOURCE

let x=30;
let y=25;
let a=10;
let b=20;
let d=45;
function setup(){
    createCanvas(500,500);
    noStroke(0);
    colorMode(HSB,50,20,120);
}
function draw(){
    //background(100);
    x+=a;
    fill(random(450),10,221);
    if((x>500)||(x<0)){;a=-a
       ;
    }  
    y+=b;
    //fill(random(255));
    if((y>500)||(y<0)){b=-b
       ;
    }
    rect(y,x,a,b);
}

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