Transparent Detail on mobile

Hi,
everybody and shader masters !

I try to create a shader on iOS (Android) that could display a double texture renderer. One with my texture with alpha and the second that is combine with the previous one and display detail when the player zoom on it.

I use unity Sprite Renderer and it seems some shader feature are not supported with this component as "fixed4".

If someone have an idea to create this shader or some tips ?

 

fixed precision is very few bits. .. you can try using half4 instead.. .it's still an optimization for mobile with with more precision.