扫描线算法消隐,鼠标左键点击4个点作为六面体底面,自动生成一个固定高度的六面体,键盘上下左右变换六面体角度-Scan line algorithm blanking, the left mouse button click on four points as hexahedron bottom, automatically generates a fixed height of hexahedral, keyboard up and down about six-sided perspectiv