code: public void vertex(double x, double y, double z) {
          MODE = LINES_3D;
          this.x.add(x);
          this.y.add(y);
          this.z.add(z);
          colors.add(this.strokeColor);
          calcG();
      }
docs: Adds the point to Lines.
  
  @param x The x-coordinate of a new added point.
  @param y The y-coordinate of a new added point.
  @param z The z-coordinate of a new added point.