The primary bow at 42 degrees, the secondary at 51 with its colours reversed, Alexander's dark band between them where no light can come back, and the supernumerary fringes inside the primary that only interference explains — every feature of a real rainbow, in its real place.
Drawn with: a WebGL2 shader.
Reacts to and looks like: gpu, webgl2 and audio-reactive.
Family: Visualiser.
Runs in your browser. The preview above is the same program the renderer uses.