Maybe Microdee has an example patch. From taking a look at the shader code here is what I see (and please someone that knows what they are doing correct this if need be):
the mix gsfx
- is expecting a byte address buffer
- that there should be a pos, normal, texcoord, vcol structure to this buffer
Now, here is the confusing part: byte address buffer ≠ structured buffer. Even though in this case the actual functionality is pretty much the same. The assimp node you are using is giving a structured buffer which I think is a different data type as far as vvvv is concerned, hence why you can’t connect the pins to the geom 1 & 2.
2nd problem, even if you could, I think your layout from the FBX is gonna have a lot of extra slots (eg tangents etc), so the byte reading offsets in the shader will be all wrong. In the case of generative geometry it’s no problem you can just declare your layout to match what the shader expects. But the FBX will have all that done in the background on export from your 3D software.
So, I guess the solution for you, would be to have an extra gsfx before the mix, so you can tell it to convert your geometry to the layout mix.gsfx wants. You can then use the buffer outputs (which I believe are byte address buffers) on the morph inputs.