Watch Variables in p5.js
Example 2.1.1: The ellipse follows the mouse around the canvas.
Example 2.1.2: In this new example the ellipse again follows the mouse around the canvas, but since the background is called only once the ellipses overlap.
Example 2.1.3: By adding noStroke() it acts like a simple drawing program.
Example 2.1.4: We can clear the drawing by having mousePressed() call background().