This is a demotool for interactive development of shader-based demos that use time-based envelopes for graphic effects.
An envelope is an arbitrary piecewise linear function that maps time into a real value. Although these can be handled in code, it is typically much easier to store and modify them externally. Envelopster is that tool to view and modify envelopes and preview the demo as a whole. You can even attach an audio file to easily synchronize your graphical effects with music!
This tool was used during development of the Right Hemisphere demo.