I'm thinking of a simple version of Winamp's visual plugins. I have a puzzle game and I would really like some simple color swells (picture a calm ocean of various colors). I have NO idea how to do this, but I feel like if I have a starting point I can get to where I need to be.
Any suggestions? I have both music and keyboard input which I intend to use as change-generators.
I'd suggest to write a fragment shader that uses combines some sine waves of different frequency, phase shifts and color (i.e. combine x and y and time in different ways, mash them together and you should get something).
To get the colors to correspond to the music, try filtering out some frequency bands, connect the intensity of each bands to the color waves above and use some filtering over time on the intensity for each band. (i.e. so that a peaking frequency gives a high output that degrades slowly over 0.2-5 seconds.)