How do you make a float array param in Shader Graph?

Unity Engine
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1

In Unity, in a Shader Graph, there is a dropdown to add params as seen in the attached image. Nowhere here is there an option that lets you create arrays, which is a very basic feature of any shader language. I see there is an option to pass in a Texture, and this can be used as a hacky workaround, but using a texture as an array has huge drawbacks:

  1. the complexity involved in having to deal with precision, texture widths/heights, converting array indices into a 2d uv index, worrying about the ranges ofthe uv and the texture, and other pointless complexity burdens.
  2. a Texture2D inherently is just going to be an array of vector4s, but maybe the shape of your data awkwardly fits into a vector4 for whatever reason.
  3. the readability is trash. It’s confusing to everybody that you are using a full texture just to store some floats.
  4. reuploading a texture every frame to the GPU has more overhead than simply uploading a float array

I need to simply have a float array. Again, in every shading language this would be trivial. I come from a GLSL and WGSL background where creating an array buffer of floats is as simple as creating a single float buffer. It would frankly be shocking and absurd if Unity could not do this.

So how do you do it?

image
image437Ă—473 10 KB

2

note, “upgrading” to the built in pipeline from URP allows you to do this, and it is pretty easy to create float arrays in an HLSL script

3

I believe you can declare an array using a dummy CustomFunction node (include an HLSL file, not inline code), like:


float YourArrayProperty[8];

void DummyFunc_float(out float Out)
{
 Out = 1;
}
void DummyFunc_half(out half Out)
{
 Out = 1;
}

image
image860Ă—561 25 KB

Just remember to connect the “Out” value to something (like a multiply by 1). This will prevent ShaderGraph removing the node.

Im unsure if this would make your Shader non SRPBatcher-compatible, as this property will be outside the UnityPerMaterial CBuffer

4

Thank you for the response. Hopefully this will help somebody. I am unable to verify that this works because I have already upgrade back to the build in render pipeline from the URP.

I suspect that this missing functionality is a far greater pain point for Unity users than what they realize, otherwise it probably would have already been implemented into URP.