For i, 0, nVertex
       GetVertexProperty ( x, i, X )
       GetVertexProperty ( y, i, Y )
       SetVertexProperty ( i, X, x / 2 )
       SetVertexProperty ( i, Y, y / 2 )
Next
For i, 0, nThings
       GetThingProperty ( x, i, X )
       GetThingProperty ( y, i, Y )
       SetThingProperty ( i, X, x / 2 )
       SetThingProperty ( i, Y, y / 2 )
Next
For i, 0, nSectors
       GetSectorProperty ( fh, i, FloorHeight )
       GetSectorProperty ( ch, i, CeilingHeight )
       SetSectorProperty ( i, FloorHeight, fh / 2 )
       SetSectorProperty ( i, CeilingHeight, ch / 2 )
Next