柱形墙开窗算法

算法源码：

@StartRule
Lot -->
    primitiveCylinder(9, 2, 4)
    comp(f) { side = Side | all = Endcaps. }
    
Side -->
    split(u, unitSpace, 0) { 2 : Split | 
                            ~1.5 : Wall. }*
           
Split -->
    split(y) { ~1: Wall. | 2: color(0,0,1,0.5)Window | 
                           ~1: Wall. }