`use_f64` feature is not additive

[nikita240]

I'm facing a problem due to feature unification caused by use_f64 not being additive.

I depend on rerun in my project, which uses tobj in f32 mode, but I also use tobj in my project, but I need f64 mode. Due to feature unification, rerun's tobj gets the use_f64 feature enabled and it starts spitting out errors from it's internal code.

error[E0308]: arguments to this function are incorrect
  --> /opt/cargo/registry/src/index.crates.io-1949cf8c6b5b557f/re_renderer-0.23.4/src/importer/obj.rs:44:22
   |
44 |             .map(|p| glam::vec3(p[0], p[1], p[2]))
   |                      ^^^^^^^^^^ ----  ----  ---- expected `f32`, found `f64`
   |                                 |     |
   |                                 |     expected `f32`, found `f64`
   |                                 expected `f32`, found `f64`
   |
note: function defined here
  --> /opt/cargo/registry/src/index.crates.io-1949cf8c6b5b557f/glam-0.28.0/src/f32/vec3.rs:13:14

[nikita240]

I understand one of the motivations is to not have to template the whole codebase.

I suggest looking at what parry does to solve this problem.