I have a GML file that I'm displaying in QGis - it contains a set of contours and they are written out in such a way that the lowest contour (largest polygon) is drawn last thus covering up all the smaller polygons. While I can work round this by writing out the GML in reverse order I was wondering if there was a way to reverse the draw order directly inside QGis.
There are ways to create symbols that should give the desired effect:
Create a symbol made of two layers: 1) a fill layer, 2) an outline layer.
Enable "Symbol layers" to tell QGIS to first render the the fill layer for all features in and then the outline layer.
How about just converting the polygons to linework? Then you wouldn't have to worry about display order.
Or maybe these previous questions will give you some suggestions you can use: