Question Using Vertex Color or 2nd UV to Store Position Doesn't Work?

I have an object formed by multiple planes in different angle. I want to rotate each plane with an angle by the axis of {0, 1, 0} in shader graph.

For testing, the mesh I am using have both vertex color and 2nd uv storing the center point of each plane. I exported the mesh as a fbx and import it into Unity. Then In the shader graph, I did something like (vertex position) - (vertex color), or (vertex position) - (2nduv). I expect all the planes will go to the origin but it doesn't happen and I am frustraed.

I really appreciate it if anyone can help me.

I attched my scene to make things more clear

My shader graph


Original mesh (with vertex color and 2nd UV storing centroid position of each plane, using vertex color and 2nd UV at the same time is just for testing)


What I want to achieve in shader graph

 

What I get

 

In Unity, uv although is a float 4, only the first 2 components can be used. So It is not enought to store a 3D positon (x,y,z). Vertex color in Unity only has 0-1 range so it is not useful either. Seems like using tangent is the way to go.

 

Using multiple uv coordinates is also valid.