1. int a;
2. int sec;
3. int olda = 0;
4. int oldsec = second();
5. void setup() {
6.   background(102);
7.   size(500, 500);
8. }
9. void draw() {
10.   a+=1;
11.   sec = second();
12.   line(olda, oldsec*4, a, sec*4);
13.   olda = a;
14.   oldsec = sec;
15. }
16. [/code]

void setup() {
  size(640, 200);
  background(102);
}

void draw() {
  stroke(255);
  if(mousePressed) {
    line(mouseX, mouseY, pmouseX, pmouseY);
  }
}