Is there a way to get rust-gpu to work with nalgebra types?

[marstaik]

Hey guys, I love the idea of the project. My question is if its possible to replace the glam:: types with those from nalgebra.

I prefer to use more mathematically based libraries (and nalgebra has glm-like wrappers too from nalgebra_glm.

It would be amazing if I didn't have to convert to glam::Vec types to pass around data for use on cpu/gpu shaders to minimize dependencies and keep my code paths clean and easy to understand.

I don't fully understand how the glam:: types get converted to SPIR-V, I looked a bit through the code and I couldn't fully find if there is any function/translation mapping going on.

Is this currently possible? Would it be a huge lift to do?

In addition to ergonomics, there are some cpu-side performance benefits of nalgebra on certain operations that are of interest.

[schell]

I don't see anything about the types themselves that would keep them from being compiled with rust-gpu. Typically the first hurdle is making sure the crate can be compiled as no_std. After that there are certain operations to avoid, such as anything that uses NaN or infinities. The best way to find out is to try it yourself! If you run into any problems please open a ticket here and we'll see what we can do :)

[schell]

You can check out this quick list of gotchas that I've run into here. It's mostly up to date.

[LegNeato]

@schell Your link does not work

[schell]

Thanks @LegNeato, I've updated the link.

[marstaik]

I've been trying to make progress on this again.. I've gotten decently far but I hit into a snag with a ptr_offset_from intrinsic:

   Compiling rtd_scene v0.1.0 (/home/marios/proj/rtd/packages/rtd_scene)
error: failed to run custom build command for `rtd_scene v0.1.0 (/home/marios/proj/rtd/packages/rtd_scene)`

Caused by:
  process didn't exit successfully: `/home/marios/proj/rtd/target/debug/build/rtd_scene-d05018d3cb45663e/build-script-build` (exit status: 1)
  --- stdout
  cargo:rerun-if-env-changed=RUSTGPU_CODEGEN_ARGS
  cargo:rerun-if-env-changed=RUSTGPU_RUSTFLAGS
  cargo:rerun-if-env-changed=RUSTGPU_CARGOFLAGS

  --- stderr
     Compiling rtd_scene_shaders v0.1.0 (/home/marios/proj/rtd/packages/rtd_scene_shaders)
  error: exactsdiv() not implemented for type u32
     --> /home/marios/.rustup/toolchains/nightly-2025-06-30-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/const_ptr.rs:671:18
      |
  671 |         unsafe { intrinsics::ptr_offset_from(self, origin) }
      |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

  error: could not compile `rtd_scene_shaders` (lib) due to 1 previous error
  Error: BuildFailed

I've managed to setup nalgebra like this in my no_std crate:

[package]
name = "rtd_math"
version.workspace = true
edition.workspace = true


[target.'cfg(not(target_arch = "spirv"))'.dependencies]
nalgebra = { version = "0.34.1", features = ["bytemuck", "glam030", "macros"] }
nalgebra-glm = { version = "0.20.0" }

[target.'cfg(target_arch = "spirv")'.dependencies]
nalgebra = { version = "0.34.1", features = ["libm-force"], default-features = false }
nalgebra-glm = { version = "0.20.0", default-features = false }

Is this something we can get from spirv?

[marstaik]

Augh, even when removing the try_inverse() call there are many more errors, I'll have to keep trying

[Firestar99]

Currently, pointers are not super well supported, so you may be running into nalgebra using them in a way rust-gpu can't quite understand them yet. See what I wrote here