code: public void setNode(int number, Vector3D v) {
          if (number <= 0) {
              number = 0;
          } else if (3 <= number) {
              number = 3;
          }
          this.points[number * 3] = (float)v.getX();
          this.points[number * 3 + 1] = (float)v.getY();
          this.points[number * 3 + 2] = (float)v.getZ();
          set();
      }
docs: Sets coordinate of nodes of this Curve.
  
  @param number The number of a node. The node whose number is 0 or 3 is a anchor point, and
  the node whose number is 1 or 2 is a control point.
  
  @param v The coordinates of this node.