条件分支的开始。
case(condition:)
case condition:
@StartRule
Lot --> primitiveCube(6, 0.2, 6)
extrude(5)
comp(f) { top: Roof | side: Wall }
Roof --> color(0.5, 0.25, 0.15)
Wall -->
case scope.sy > 4 : TallWall
else : ShortWall
TallWall --> color(0.8, 0.3, 0.3)
ShortWall --> color(0.3, 0.6, 0.8)