// https://p5js.org/reference/

​

let size = 25;

​

function setup() {

  createCanvas(400, 400);

}

​

function draw() {

  background(220);

​

  // Change color if mouse button is pressed

  if (mouseIsPressed) {

    if (mouseButton === LEFT) {

      stroke(255, 0, 0);

    } else if (mouseButton === RIGHT) {

      stroke(0, 255, 0);

    } else if (mouseButton === CENTER) {

      stroke(0, 0, 255);

    }

  } else {

    stroke(0, 0, 0);

  }

​

  // Draw a circle wherever the mouse is.

  circle(mouseX, mouseY, size);

}

​

// Change circle size if mousewheel scrolled

function mouseWheel(event) {

  size += event.delta * 5;

  //uncomment to block page scrolling

  //return false;

}

​