Geometry generators allow us to modify and create geometries. Using expression engines, they allow us to modify or generate geometry on the fly and to have different geometries stacked together, allowing us to make creating complex rendering an easy and feasible task. They can be used to perform different operations on point, line, and polygon data, and using the expression engine, we can generate advanced symbology.
Now, we will use the dhaka_gazipur.shp file to see some of the geometry generators you can use with polygon data:
This shapefile has two polygons. Suppose that we want to get the geometric center of these two polygons. This can be very easily achieved using centroid($geometry) as an expression for Geometry generator. To do this, we first click on Open the Layer Styling panel 
in the Layers panel. This will open the...
