!7

p { pMain(HeartBeat); }

public sclass HeartBeat extends PApplet {
  public void settings() { size(1200, 400); }
  
  int x = 0;
  float py = 0;
  float scale = 2;
 
  public void setup() {
    background(0);
  }
 
  public void draw() {
    noStroke();
    fill(0,0,0,15);
    rect(0,0,width,height);
    translate(0,height/2);
    scale(scale);
    x++;
    x%=width/scale;
    float fx = py + random(-20,20);
    stroke(100,255,100);
    noFill();
    line(x-1,py, x,fx);
    py = minmax(fx, -height/2/scale, height/2/scale);
  }
}

Began life as a copy of #1013742