Draw Square

int value = 0;

void setup() {
  size(800, 800);
  randomSeed(0);
  noLoop();
}

void draw() {
  float cX = mouseX;
  float cY = mouseY;
  float len = random(10,25);
  translate(cX-len/2, cY-len/2);
  float rad = random(0, PI*2);
  rotate(rad);  
  rect(0, 0, len, len);
  float fr = random(0,255);
  float fg = random(0,255);
  float fb = random(0,255);
  fill(color(fr,fg,fb));
}

void mouseDragged() 
{
  value = value + 5;
  if (value > 255) {
    value = 0;
  }
  redraw();
}