/* In this example, the canvas is painted with a trail of circles, based on following the mouse position. */ // This function is executed only once, at the very beginning void setup() { size(500,400); background(255); fill(128, 128, 255); } // This function is repeatedly call in an implicit loop. // A single call is responsible for drawing a single frame. void draw() { ellipse(mouseX, mouseY, 20, 20); }