var RANDCIRC = false; //enabled/disabled with 'c' key

​

function setup() {

  createCanvas(500, 500);

  background(255);

  noStroke();

}

​

function draw() {

  //not drawing a background every frame because we want

  //it to be treated like a piece of canvas that we are adding shapes to

​

  //if the RANDCIRC brush is enabled (RANDCIRC == true)

  if (RANDCIRC == true) {

    //set a random fill color that is mostly transparent

    fill(random(150, 200), random(150, 200), random(150, 200), 10);

​

    //draw a circle at the current mouse position

    //draw it larger if the mouse is held down than if it isn't

    if (mouseIsPressed) {

      ellipse(mouseX, mouseY, 200, 200);

    } else {

      ellipse(mouseX, mouseY, 100, 100);

    }

  }

}

​

//code inside the keyPressed function runs whenever a key is pressed

function keyPressed() {

  //'c' is the toggle for the first brush, RANDCIRC

  if (key == "c") {

    RANDCIRC = !RANDCIRC; //! negates the value, so T -> F; F -> T

  }

  //clear the screen with the 'r' key

  if (key == "r") {

    background(255);

  }

  //save the sketch with the 's' key

  if (key == "s") {

    save("output.png");

  }

}

​