Using different shaders based on desktop or mobile?

Question

Most of my assets use the Unity standard shader. It looks and runs fine on Desktop, but on mobile the performance isn't good.

I assume the solution is to switch to one of the mobile friendly vertex-lit shaders for mobile. But how can I switch shaders depending on platform? Is there a way that Unity can do this for you, or do I need to manually change them before building? Also, would I be able to just specify the shader, or would I need to create all new materials for all my assets?

I really have no idea how to approach this, and I'd appreciate it if I can be pointed in the right direction.

Answer 1

It may lead to longer load times, but you could switch shaders in Awake based on the platform:

// Your Assets folder should contain a folder called Resources,
// containing a shader called mobileShader
Shader mobileShader = Resources.Load("mobileShader") as Shader;

// Called when a GameObject with this script is loaded
void Awake() 
{
    // Check if we are on mobile
    if (Application.platform == RuntimePlatform.Android || Application.platform == RuntimePlatform.IPhonePlayer)
    {
        // Change just the shader
        GetComponent<Renderer>().material.shader = mobileShader;
    }
}

Answer 2

You can also use shader compile directives in custom shaders to skip over expensive sections, resulting in a simpler look, which only triggers when on a mobile device.

https://docs.unity3d.com/Manual/SL-MultipleProgramVariants.html

I've got a shader I wrote which uses that feature that wraps around a visual effect, the effect can then be disabled in the in-game options menu (and being purely visual, although cool, the game play isn't changed).