Alloy has a preview shader designed to work with Allegorithmic's Substance Designer tool to provide a mostly accurate preview of how the resulting material set will look in Unity 5 using Alloy.
- Copy the "Substance Designer Custom Shader.zip" file from your Alloy project packages directory into the a different directory outside your Unity project.
- Extract the contents into a folder.
- Open Substance Designer and either create or open a project.
- In the "3D View" sub-window, select "Materials/Default/Shader/Load...".
- In the load dialog, navigate to the folder with the alloy preview shaders, and select the "*.glslfx" file for whichever shader you wish to load.
- In the "Explorer" sub-window, click and drag your substance from the project tree and drop it on the scene in the "3D View" sub-window to refresh the values for the shader.