ShaderGraph - Can't offset vertex position by texture lookup

Hi!

I'm playing around with shader graph and evaluating it to see if I can use it in a new project. I'm trying to do something fairly trivial and think I'm misunderstanding something somewhere.

I'm trying to do a texture lookup (greyscale texture), then offset the vertex.y position by that amount.

The problem I'm having is I can't connect the result of the Add to the position input on the PBR master node.

I'm sure i'm doing something wrong here. Is it because I'm mixing color vec3 with positional vec3?

I've attached a screenshot of my graph.

 

Amazing thanks very much, that fixed it!

 

Nice, but can you explain the difference between these two nodes ?

 

Because in this case the texture don't use the UV i made on my object.

 

The basic Sample Texture 2D uses a fragment shader function in which the GPU automatically determines the appropriate mip map level of detail to use based on how much the UV changes between the pixel being drawn and the pixels next to it.

This doesn't work in a vertex shader because the GPU doesn't know where that vertex is on screen, or how it relates to the surfaces that will eventually be drawn with it.

Sample Texture 2D LOD let's you explicitly choose the mip level yourself.

 

Is there an alternative for the triplanar node we can use? (Other than building our own triplanar projection with Sample LOD nodes)