Time for another fresh example for the Graphics Dojo. This time I present a small tool that does nothing but showing the famous HSV cylinder. To give some realism, subtle blurred reflection is also added but can be easily disabled. Manual full-scene anti-aliasing is provided by the usual multisampling approach. Everything is done using pure QImage per-pixel manipulation along with some tricks, no OpenGL (or even its GLSL) is involved.
Note that the tool is not optimized for speed (evidenced by lots of setPixel() calls) so there is definitely room for improvement. Some possible further enhancements left as exercises for the readers are interactivity (mouse dragging to change e.g. the depth of the pie) and threaded rendering (so that the application remains responsive, just adapt the Mandelbrot example).