Introducing NormalPainter, the image editor which let's you edit normal maps using either a joytstick or the tilt of a graphical tablet pen. This revolutionary approach makes it much more convenient to handpaint normal map, a process which previously required sampling the normal color everytime. There also are other convenient ways to input normal direction which do not require a physical device, such as pinning. Check out the video for a visual example of this
This tool sure is very specialized. In most cases generating normal maps is the easiest option. But when developing a cartoonish 2D game with dynamic lighting, this tool really shines over handpainting with a regular image editor. The author produced it mainly to speed up the development process of their game MakerKing, but now released it for everyone as a free and open source software.
You can download it here https://green-frisbee.itch.io/normalpainter and check the source code here https://github.com/WinterAlexander/NormalPainter