Qt 6 Overview

 The RHI introduced in Qt 6 is a graphics abstraction layer that enables writing rendering code once and translating it for each target platform to the best-suited, native graphics API, such as Vulkan, Direct3D, Metal, or OpenGL.

The RHI enables running Qt across platforms with the best graphics performance, utilizing lower CPU overhead and better GPU utilization.

 Qt Quick 3D is a high-level API in Qt 6 for creating 3D user interfaces based on Qt Quick. It allows merging 2D and 3D content for fluid, next-level UIs, and comes with significant improvements and additions.

For example, the API allows customizing 3D particles and using vertex animations, such as simulating deformations of soft materials with mesh morphing or abstract representations of model movements with skeletal animation.

The API also provides an ability to create immersive experiences, including support for virtual reality (VR) and augmented reality (AR) platforms. 

 Qt 6 provides highly evolved support for stunning, hardware-accelerated graphics with shader effects, particles, and other advanced UI effects with Qt Shader Tools.

It also provides an ability to use vector images and animations (SVG and Lottie) as a scalable part of the UI. 

 Qt Quick and the declarative QML language have continued to evolve, enabling highly dynamic, cross-platform GUIs with a clear separation from the backend.

Qt Quick and QML come with many improvements in Qt 6. For example, the renewed Qt Quick Controls enable pixel-perfect, native looking UI elements and their better re-use. Fractal scaling support allows for automatic UI scaling for different monitor configurations. Qt 6 also features advanced UI performance, out-of-the-box accessibility, and improved font rendering and support for modern fonts.

 In addition to the graphics rendering, Qt 6 comes with various performance improvements.

Revamped concurrency APIs allow for multiple CPUs and parallel computation to keep your UIs fluent while doing backend logic in the background. Tasks automatically scale depending on the hardware.

The new QProperty System increases code speed with binding support in C++, bringing the best part of QML to Qt with seamless integration to QObject.

Update to the latest standards such as C++17 (and C++20) improves code readability, provides better performance​ and eases maintenance.

 The new Qt Graphs module integrates 2D and 3D data visualization, making it more intuitive and convenient to use, and allowing to create and customize interactive, hardware-accelerated graphs, from simple plots to complex visualizations.

Advanced techniques such as volumetric rendering or 2D slicing from 3D provide more opportunities to visualize your data.

The use of the new Qt Quick 3D and RHI capabilities allow turning even larger datasets into responsive graphs, also for real-time data. Major rework has also been done on data APIs and use of proxies.

 Qt 6 allows creating your own protocol backends and integrating them into the default Qt workflow. Security-related features are added automatically.

Qt 6 provides ready-made support for various networking & connectivity protocols and standards, including HTTP, GRPC, and Protocol Buffers, as well as cross-platform data handling capabilities to exchange, save, query, manipulate, and serialize data.

 Qt 6 introduces various improvements to deployment, unit testing, and tooling.

Automated GUI testing allows efficient functional regression testing and system testing of cross-platform GUIs and HMIs.

Code coverage testing in the Qt Creator IDE enables analyzing the test and code coverage of C++ and QML code.

The revamped CMake support allows using the industry-standard build system, with its wide feature set and large ecosystem to build your Qt applications.

In addition, there's a wealth of supported target platforms and devices.