具有2D和3D效果的绘图工具，2d文件夹内是画板，详情见里面的说明。3d文件夹内只是个简单的3d演示，用方向键控制角度，可执行文件在里面的release文件夹内。-2D and 3D effects with the drawing tools, 2d is the Sketchpad folder, as detailed in the note inside. 3d folders only a simple 3d demo, use the arrow keys to control th