Interactivity and 2D drawing

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void setup() {  

  // sets up the canvas size

  size(250, 250);

  // sets background to (255, 255, 255) (R, G, B)

  background(255);

}

​

void draw() {

  // noise() takes an argument and generates smooth

  // random values in the range (0, 1)

  float n = noise(frameCount);

  // map() maps n from the (0, 1) range on to

  // a range more useful for drawing

  float size = map(n, 0, 1, 5, 65);

  noStroke();

  // mousePressed is true if the mouse is depressed

  if (!mousePressed) {

    fill(153);

    // tell Processing to interpret the arguments

    // to rect as indicating the center of the rect

    // as opposed to the first corner

    rectMode(CENTER);

    // draw a rect at the current mouse location

    // with size size

    rect(mouseX, mouseY, size, size);

  } else {

    fill(255);

    ellipse(mouseX, mouseY, size, size);

  }

}

​