public void curve(float x1, float y1,
                    float x2, float y2,
                    float x3, float y3,
                    float x4, float y4) {
    beginShape();
    curveVertex(x1, y1);
    curveVertex(x2, y2);
    curveVertex(x3, y3);
    curveVertex(x4, y4);
    endShape();
  }