VC6.0实现多边形裁剪。单击左键记录目标多边形，右键记录多边形定点，双击右键闭合多边形。再左键记录裁剪多边形，右键记录多边形定点，双击右键闭合多边形。实现裁剪。-VC6.0 achieve polygon clipping. Click the left records the target polygon, right-record fixed-point polygon, double-click the right-closed polygon. Polygon Clipping rec