Thanks for the link 
. Here is how I solved it in my case, where I needed to store and read Vector3s.
Render target settings
- I had to set the Texture Group to 2D pixels to be able to properly read the data in the material graph
- Set Size X and Size Y to the size of your “array”. In my case it’s a 2D array of 256x2
How to store the data
How to read data from the render target within the material graph
Add a custom node to the graph, with the following code and inputs:
- Tex: your render target texture
- PixelCoordinates: the coordinates of the pixel that holds the data you need
- TexSize: the size of your render target (In my case 256x2). There is maybe a more dynamic way to get the texture size, but this is good enough for me.
HLSL Code:
float2 UV = PixelCoordinates/TexSize;
float3 data = Texture2DSample(Tex, TexSampler, UV);
return data;
The output will be the data that you stored earlier