If you have a valora work running and change the GLSL on disk, it will recompile and update in the next frame without your having to relaunch or any inconvenience like that.
shaders. opengl does recompile them but all while your os executable is running. its a very useful and easy thing to set up live shader reloading. much quicker cycles to experiment.
I've been wondering where are the non-destructive painting programs, which does not rasterize organic brushes or strokes.
Your attempt could work as a base to build one if it can work realtime sufficiently fast.