private void drawFan(PVector ursprung, PVector[] rand) {
    beginShape(TRIANGLE_FAN);
    vertex(ursprung.x, ursprung.y, ursprung.z);
    for (int i = 0; i < rand.length; i++) {
      vertex(rand[i].x, rand[i].y, rand[i].z);
    }
    vertex(rand[0].x, rand[0].y, rand[0].z);
    endShape();
  }