In Unity (builtin pipeline), how would I call CalculateLevelOfDetail or equivalent based on a sampler2d (and uvs)? All examples seems to use a separate Texture2D and SamplerState, but then I'd have to rewrite the whole shader to use those. Internally, methods like tex2d, which take a sampler2d, must get access to the SamplerState somehow, but I can't find anything about how to access Texture2D and SamplerState from a sampler2d...