Pulling it all together #1

sketch.js

var startColor;
var endColor;
var counter;
var bgColor;
var y = 0;
var ySpeed = 1;

function setup() {
  // uncomment this line to make the canvas the full size of the window
   	createCanvas(windowWidth, windowHeight);
	startColor = color(255,0,0);
	endColor = color(127,30,200);
	counter = 0;
	bgColor = lerpColor(startColor, endColor, counter);

}

function draw() {
  	// draw stuff here
  	background(bgColor);
  	counter = counter + .01;
	bgColor = lerpColor(startColor, endColor, counter);
	noStroke();
	fill(0);
	ellipse(width/2, y, 30, 30);
	y = y + ySpeed;
}

function keyPressed() {
	counter = 0;
}
function mousePressed() {
	ySpeed = ySpeed * -1;
}

function mouseDragged() {
	ySpeed = ySpeed * 1.01;
}