The polygons are not arranged

[ghost]

Hello! Thanks for your library.
I generate a series of poygons at random, and the polygons can be drawn on a widget with Qt. I can also output the vertexes with the function Item::toString. However, the number of bins that used is always zero, The result polygons' postion also haven't been changed. What the mistake I make.
Here is the output

Here is the polygons I generate

Here is the screenshoot of code

[tamasmeszaros]

Check the input, make sure that: all polygons are oriented clockwise and the first vertex is identical to the last vertex.