Viewport 2.0 vertex shader and custom buffer

Hi everyone,
I am new to plugin development in Maya and I need to make a custom vertex shader for viewport 2.0.
The problem i have is I would need at some point in the vs to sample from a float buffer
I am not talking about geometry data here but custom buffer of arbitrary size (TBO/SSBO for example)

It doesn’t matter if dx or gl viewport. I have tried to look at dx11Shader.mll and glslShader.mll plugins but it seems that parameters are passed through pre defined semantics and nothing here mentions buffers.
These plugins seems to be the simpliest route to add custom shaders to vp2 though, I have looked at MPxHwShaderNode and MPxShaderOverride but these routes get complex and confusing really fast.
Any hints would be greatly appreciated.
Thanks :smiley: