Accessing pose-space vertex data prior to GPU skinning

Hi, I was looking to creating a damage system similar to left 4 dead 2 one outlined here:
http://www.valvesoftware.com/publications/2010/gdc2010_vlachos_l4d2wounds.pdf
As you can see in the paper they cull sections of the model by subtracting an ellipsoid from the mesh when it is in pose-space, I was looking to do this in Unity but I cant find much information on the skinning pipline.

I assume the gpu skinning is done in a vertex shader pass prior to rendering but I cant find anyway to access it without scrapping the skinnedmesh renderer component and writing an entirely custom gpu skinning shader which is way outside the scope of this project as its just a bit of fun.

Can anyone shed any light on whether its possible to achieve this within the existing unity skinning pipeline?

Thanks,

 

Unity does CPU skinning normally, or with DX11 does GPU skinning in a way that pre transforms the mesh before the shader sees it. Either way there's no way to get the vertex positions unmodified.

It's still possible to do what you want though. Just store the initial vertex positions in the vertex color, across two texture uv slots, or in another texture assuming you have unique UVs for the character. Vertex color would be the easiest, and you can use an interpolated half3 instead of the incoming fixed4 value to get smooth positional information in the pixel shader.

 

Ahhhh I didnt think of that at all, thats a great idea thanks bgolus!