PGraphics pgBg, pgFg;

void setup() {
  size(640, 360);

  //PGraphic Background
  pgBg = createGraphics(width, height);
  // PGgraphic Foreground
  pgFg = createGraphics(width, height);
}

void draw() {
  background(0);

  // Background PGraphic circle with white outline
  pgBg.beginDraw();
  pgBg.clear();
  pgBg.stroke(255);
  pgBg.strokeWeight(10);

  // replace this by the contour.draw();
  for (int i = -100; i <= 100; i += 50) {
    pgBg.ellipse(mouseX-15 + i, mouseY-15, 30, 30);
  }
  pgBg.endDraw();


  // Foreground PGraphic Blue circle with red outline
  pgFg.beginDraw();
  pgFg.clear();
  pgFg.fill(0, 0, 255);
  pgFg.stroke(255,0,0);
  pgFg.strokeWeight(4);

  // and ALSO replace this by the same contour.draw();
  for (int i = -100; i <= 100; i += 50) {
    pgFg.ellipse(mouseX-15 + i, mouseY-15, 30,30);
  }
  pgFg.endDraw();

  image(pgBg, 0, 0);
  image(pgFg, 0, 0);
}