Type Alias UserSpecializeFn 

pub type UserSpecializeFn = fn(&(dyn Any + 'static), &mut RenderPipelineDescriptor, &MeshVertexBufferLayoutRef, ErasedMaterialPipelineKey) -> Result<(), SpecializedMeshPipelineError>;

A type erased function pointer for specializing a material prepass pipeline. The implementation is expected to:

• Look up the appropriate specializer from the world
• Downcast the erased key to the concrete key type
• Call SpecializedMeshPipelines::specialize with the specializer and return the resulting pipeline id