I've made an attempt at creating some Luma Waveform display using ShaderToy ,
This is my first shader so there may be some improvements to be done, but at least it seems working...
Here are some screenshots :
You can get the shader here :
Lumascope_04.txt (836 Bytes)
Don't hesitate to modify it and redistribute it, I hope something like this can be implemented in Natron one day