Draw on the canvs with left mousebutton, erase with the center button, reset the canvas with ESC.
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function setup() {
createCanvas(windowWidth, windowHeight);
background(255);
frameRate(30);
}
function draw() {
//background(255,255,240,5);
//ellipse(mouseX, mouseY, 80, 80);
fill(255,255,255);
noStroke();
rectMode(CENTER);
fill(random(255),random(100),random(25));
ellipse(mouseX,mouseY, 500,500,20);
fill(random(255),0,random(255));
//beim drücken von escape-taste reset die Zeichenfläche.
if(keyIsPressed == true && keyCode == ESCAPE){
background(100);
}
}