code: public void setNode(int number, double x, double y) {
          if (number <= 0) number = 0;
          if (number >= 3) number = 3;
          this.points[number * 3] = (float)x;
          this.points[number * 3 + 1] = (float)y;
          this.points[number * 3 + 2] = 0;
          set();
      }
docs: Sets x,y,z-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 x The x-coordinate of this node.
  @param y The y-coordinate of this node.