KDAB's City Lights Display with Qt 3D

The City Lights demo is an example of Qt 3D being put to novel use to implement a deferred rendering pipeline.

With OpenGL, the number of lights you can show on a screen, also affecting objects in a scene, is limited by the need to use a forward renderer. Using Qt 3D, the geometry considerations can be separated out from the lighting ones, which massively reduces the complexity. This enables the scene in this demo to run on fairly mediocre hardware at 60 frames a second, even though it contains approximately 1500 real time lights.

KDAB Director, Dr Sean Harmer, maintainer of the Qt 3D project, explains.