Creating a uniform block with lifetime parameters

[fcrisafulli-dev]

I am trying to streamline my uniform pipeline by using uniform blocks. I want to create a block called StaticUniforms which is created using glium::uniforms::UniformBuffer::immutable. Based on the documentation this should be reserved for uniforms which do not change much if at all.

My current layout looks like this:

use glium::{implement_uniform_block, uniforms::Sampler, texture::SrgbCubemap};

#[derive(Clone, Copy)]
pub struct StaticUniforms<'a> {
    pub u_perspective: [[f32;4];4],
    pub u_skybox: Sampler<'a, SrgbCubemap>
}
implement_uniform_block!(StaticUniforms,u_perspective, u_skybox);

I am able to successfully create and use this uniform block with just the perspective matrix.

However, when I try to add a Sampler<'_, T> the implement_uniform_block! macro yields the compiler error: the trait bound 'Sampler<'_, glium::texture::SrgbCubemap>: glium::uniforms::UniformBlock' is not satisfied

Further investigation shows that this might be an issue with the macro itself as the full diagnostic yields:

error[E0726]: implicit elided lifetime not allowed here
 --> src\glib\uniform.rs:8:1
  |
8 | implement_uniform_block!(StaticUniforms,u_perspective, u_skybox);
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected lifetime parameter
  |
  = note: assuming a `'static` lifetime...
  = note: this error originates in the macro `$crate::implement_uniform_block` which comes from the expansion of the macro `implement_uniform_block` (in Nightly builds, run with -Z macro-backtrace for more info)
help: indicate the anonymous lifetime
 --> C:\Users\usr\.cargo\git\checkouts\glium-77a94afc886844c8\bdb70bc\src\macros.rs:369:75
  |
36|             impl<$($gs)*> $crate::uniforms::UniformBlock for $struct_name<'_, $($gs)*> {
  |                                                                           +++

Should I simply modify the macro as the compiler suggests? Or is there a different way to use structs with lifetime parameters within a uniform block?

[Melchizedek6809]

Thank you for opening this issue. It does sound like a problem with glium, I'll try and look into it on the weekend. Could you maybe upload a full example somewhere? That way it's easier for me to test whether it fixes the actual issue.

[fcrisafulli-dev]

It might not actually be an issue with Glium. The shader compiler doesn't allow for samplers to be used within a uniform block anyways.