float myValue;
float myColour;
void setup(){
size(300,200);
background(0);
framerate(20); // setting the speed with framerate.
}
void draw(){
myValue = random(30,225);
myColour = random(30,200);
noStroke();
rect(myValue,48,40,100); // myValue - back and forward on the x axis.
fill(myColour,0,100); // random is a variety of R between the above.
}