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pop / push operation

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    Syntax

    • [ ]

    Description

    The [ operation pushes the current shape onto the top of the shape stack. It must be matched by a succeeding ] operation, which pops the shape on top of the shape stack and deletes the shape.

    Related

    • center operation
    • NIL operation

    Examples

    Rotation

    In this example, the extruded shape is rotated three times and assigned to a new shape (X). The rotations build on each other.

    Lot-->
	extrude(15)
    
	r(scopeCenter, 0, 22.5, 0) X 
	r(scopeCenter, 0, 22.5, 0) X
	r(scopeCenter, 0, 22.5, 0) X
    		Extruded shape with rotation

    Encapsulating the rotations and "create shape" operations with a push/pop pair makes all X coincide. The rotations are independent of each other.

    Lot-->
	extrude(15)
    
	[ r(scopeCenter, 0, 22.5, 0) X ]
	[ r(scopeCenter, 0, 22.5, 0) X ]
	[ r(scopeCenter, 0, 22.5, 0) X ]
    		Extruded shape with rotation using createShape

    House

    Both rules generate the same result. In the second rule, the roof is generated first using push/pop operations. 

    House -->
    extrude(10)
    comp(f) { top : roofHip(45) Roof. | all = House.}
	
House -->
    [ t(0,10,0) roofHip(45) Roof. ]
    extrude(10)
    comp(f) { top : NIL | all = House. }
    		House rule

    Translation

    Cylinder assets are inserted five times. Each scope is translated based on the scope of the initial shape. 

    House-->
    Cylinder
    [ t(  0, 0, ' 1) Cylinder ]
    [ t(  0, 0, '-1) Cylinder ]
    [ t(' 1, 0,   0) Cylinder ]
    [ t('-1, 0,   0) Cylinder ]

Cylinder -->
    primitiveCylinder(16, 1, 2)
    		Cylinder assets

    Condition

    Conditional and stochastic statements must not have preceding operations. Use push and pop to encapsulate a case switch. 

    Lot -->
    s(1,1,1)
    [ case scope.sx == 1 : primitiveCube() Cube.
      else : primitiveCylinder() Cylinder. ]
    		Conditional switch

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