float spacer = 20;

void setup(){
  size(640, 640);
  noLoop();
  stroke(30, 80);
}

void draw(){
  background(220);
  drawAngleGrid(0.0 + random(-1, 1));
  drawAngleGrid(30.0 + random(-1, 1));
  drawAngleGrid(60.0 + random(-1, 1));
}

void drawAngleGrid(float offset){
  pushMatrix();
  rotate(radians(offset));
  for(float x = -width ; x < width*2 ; x += spacer){
    line(x,  -height, x, height*2);
  }
  for(float y = -height ; y < height*2 ; y += spacer){
    line(-width, y, width*2, y);
  }
  popMatrix();
}