int screenX = 500;
int screenY = 500;
int maxRunners = 100;
ArrayList runners = new ArrayList();
int mousePressX = 0;
int mousePressY = 0;



class Runner {
  float x0, y0, x1, y1, x2, y2, x3, y3;
  int r,g,b;
  float xstep = 30;
  float ystep = 30;

  Runner (float x, float y) {
    this.x0 = this.x1 = this.x2 = this.x3 = x;
    this.y0 = this.y1 = this.y2 = this.y3 = y;
    r = int(random(150,255));
    g = int(random(0,25));
    b = int(random(0,25));
  } 

  void setStep(float x, float y) {
    this.xstep = x;
    this.ystep = y;
  }

  void setColor(int r, int g, int b) {
    this.r=r;
    this.g=g;
    this.b=b;
  }


  void goRun() {
    x0 = x1; 
    x1 = x2; 
    x2 = x3;
    x3 = x3 + random(-xstep, xstep);
    y0 = y1; 
    y1 = y2; 
    y2 = y3;
    y3 = y3 + random(-ystep, ystep);
    stroke(r,g,b);
    curve (x0, y0, x1, y1, x2, y2, x3, y3);
  }

}

void setup() {
  size(screenX,screenY); 
  framerate(30);
  background(0);

  for (int i=0; i<maxRunners; i++) {
    //runners.add(new Runner(random(0,screenX), random(0,screenY)));
  }

}

void draw() {

  fill(0,5);
  noStroke();
  rect(0,0,screenX, screenY); 

    for (int i=0; i<runners.size(); i++) {
    Runner r = (Runner)runners.get( i);
    r.goRun(); 
  }
}

void mousePressed() {
  mousePressX = mouseX;
  mousePressY = mouseY;
}

void mouseReleased() {
  Runner r = new Runner(mouseX, mouseY);
  r.setColor(0,255,0);
  r.setStep(abs(mousePressX-mouseX),abs(mousePressY-mouseY));
  runners.add(r);
}

void keyPressed() {
 runners = new ArrayList();
}